Mark Enarson Images: Blog http://www.markenarson.com/blog en-us (C) Mark Enarson Images info@markenarson.com (Mark Enarson Images) Sun, 24 Mar 2013 16:14:00 GMT Sun, 24 Mar 2013 16:14:00 GMT http://www.markenarson.com/img/s/v-5/u308581055-o625613926-50.jpg Mark Enarson Images: Blog http://www.markenarson.com/blog 120 62 Spring in Monterey Bay http://www.markenarson.com/blog/2013/3/spring-in-monterey-bay Each spring, the Monterey Bay National Marine Sanctuary plays host a series of spectacular natural events as the cycle of birth and death plays out for its inhabitants.  Monterey Bay is a wide bay along the central coast of California, bisected by the largest and deepest submarine canyon in the Pacific.  This canyon draws deep pelagic water within a few miles of shore and generates the forces that lie at the base of these annual events.  The Monterey Canyon begins at Moss Landing, located at the middle of Monterey Bay and extends about 95 miles out into the Pacific Ocean ending in the Monterey Fan nearly 12 000 feet below the surface.

Sea otter eating a crab

Near the town of Moss Landing, the Elkhorn Slough is one of California’s largest wetlands winding in seven miles from the shoreline.  This reserve provides an important resting and feeding environment for a large variety of animal life including more than 340 species of birds.  The tidal marsh contains wading birds such as the black necked stilt and long-billed curlew which probe below the surface for aquatic invertebrates.  Larger birds such as egrets search for fish in the shallows while song birds like the red winged black bird perch from reeds.

Long-billed curlew

Trips into the bay typically begin from further south in the city of Monterey.  From the boat docks at Fisherman’s Wharf boats travel out into the heart of the bay.  In these protected waters around the wharf, marine birds such as the Pacific loon paddle around and harbor seals sun themselves on exposed rocks.  Leaving the wharf, boats pass the breakwater covered in young male California sea lions and nesting Brandt’s cormorants.  In the springtime.  During the breeding season, Brandt’s cormorants develop a bright blue gular pouch below their bills which are unique amongst cormorants and fade quickly after the nesting season.  These cormorants are colonial nesters.  The male stakes out a nesting site and seeks to attract a female to it.  In attracting the female, the male cormorant performs an elaborate dance involving exaggerated wing postures and twisting of its neck.  Once paired up, the male and female cormorants will construct a nest made from seaweed, eelgrass and algae gathered from the surrounding waters.  The male gathers the supplies while the female builds the nest.  The nesting site is then protected by the pair acting in unison against surrounding cormorant pairs and even giving much larger sea lions a painful nip if necessary.

In the waters around the breakwater, sea otters dive for molluscs, crabs, and other small prey.  Molluscs are opened by smashing them against stones held on the otter’s belly as it slowly swims on its back.  Adult sea otters are the heaviest members of the weasel family but they are small for marine mammals leaving them particularly vulnerable to predators.  As a result, the otters prefer the protected waters of the marina or the kelp forests that lie close to shore.  In the spring, some female otters can be seen carrying their small babies on their bellies as they swim.  The sea otters gain protection from the cold from an exceptionally thick fur coat which is the densest in the animal kingdom.  This coat traps air and the resulting buoyancy is too much for the young babies to overcome so they can not dive under the water.  When danger approaches, the mother otter will grab the baby by the scruff of its neck and pull it under the water with her.  This buoyancy also allows the mother to leave a sleeping baby floating on the surface while she dives for food.

Sea otter protecting her baby

Around the corner of the breakwater, rafts of California sea lions bask in the water, regulating their body temperatures in the cold water by elevating a flipper above the surface to capture the warm sun rays.  While they rest along the breakwater and rocky shores, these sea lions hunt for fish out over the edge of the deep submarine canyon.  Depending on food availability, the sea lions may hunt alone or in large groups.  These groups provide a degree of protection to help watch out for predators such as transient orcas and white sharks that hunt these waters.  Out over the canyon, the sea lions can dive deep into the cold water slowing their heart rates to allow them to remain submerged for up to ten minutes before surfacing for rest and air.  The sea lions are often seen alongside whales, dolphins and sea birds hunting cooperatively on the large schools of bait fish.

Each spring and summer, bait fish thrive in the waters near the canyon as a result of the forces of upwelling.  Upwelling occurs when surface waters are heated by the sun and water layers stratify into warmer surface and cold deeper waters.  Winds blow the warm surface water offshore at a 90 degree difference to the prevailing wind and current direction due to the effects of the earth’s rotation.  As the warm, nutrient poor surface water is blown offshore, cold water rises from below carrying sediment up from the bottom.  The sediments carried by the cold water upwelling provide nutrients to phytoplankton resulting in blooms that feed zooplankton which are in turn eaten by small fish.  As a result, giant schools of small fish populate the waters over the canyon attracting larger predators.  

The first animals you tend to notice at the feast are flocks of pelagic birds.  Amongst the smallest birds in these mixed flocks are the red-necked phalarope.  These phalaropes are small waders which typically feed in shallow waters.  However, unlike most waders, they can also be found feeding in deep pelagic waters in areas of upwelling such as the Monterey Canyon.  Almost all of the non-breeding season is spent in the open water.

A medium sized bird, the sooty shearwater is found in large numbers in the waters over the Monterey Canyon.  These amazing birds breed mainly around small islands in the southern oceans and follow spectacular long-distance migrations, traveling in a circular route around entire ocean basins.  Shearwaters breeding in New Zealand may travel more than 45 000 miles in a year averaging more than 300 miles per day.  They do not make these incredible migrations in a flock but rather as single individuals that associate with other migrants only opportunistically.  When flying over the water, the shearwater dips from side to side on stiff wings with few wing beats and wing tips almost touching the water.  The shearwater is an accomplished diver, reaching depths of up 220 feet in search of fish and squid.  They most commonly take surface food but will often follow diving whales to catch fish disturbed by the leviathan.

Sooty Shearwater

Much larger is the black-footed albatross with its two to three foot long body and an impressive wing spin of up to seven feet.  The black-footed albatross breeds on mid-Pacific islands and spends the non-breeding season along the Pacific coast of North America.  During the non-breeding months, these birds usually stay at least 12-18 miles off shore feeding in pelagic waters.  It mostly eats the eggs of flying fish as well as fish and squid and to a lesser extent crustaceans.  It typically scoops up its food from the surface of the ocean relying on flying fish eggs which are easier to locate on the surface during the day.

Another larger surface feeding bird, the Western gull, is also common in these Monterey feeding groups.  Like the albatross, the gull is unable to swim or dive below the water surface and depends on food available to its reach from the surface.  The gull is a large and aggressive bird which helps to make up for its inability to dive.

In addition to the large groups of pelagic birds and sea lions hunting along the canyon, a variety of dolphin species may be seen in the vicinity of the canyon or on the trip out from Monterey.  Two of these dolphin species, the northern right whale dolphin and Risso’s dolphin, have unusual appearances.  The northern right whale dolphin along with its southern cousin are the only dolphins that completely lack a dorsal fin resulting in a sleek, hydrodynamic, torpedo shape.  The northern variety has a striking color pattern of mainly slick inky black with a white ventral patch that runs along the underside from front to back.  There are also smaller white patches on the tip of the rostrum (front) and on the undersides of the flippers.  The northern right whale dolphin is highly gregarious, usually living in groups of 200 but up to 2000-3000 and often joining with other dolphin species in large mixed pods.  The northern right whale dolphin is seen most often in cool, deep, offshore waters where they mostly feed on squid and lantern fish, although a variety of surface and midwater fish are also taken.

Risso’s dolphins are robust and stocky with a bulbous head and no beak.  At birth, a Risso’s dolphin is uniform light grey in color but as the animal ages it darkens and accumulates numerous scratches and scars from the beaks of squid and from the teeth of other Risso’s dolphins resulting from their typically rough and physical social behaviors.  These dolphins feed mainly on squid, crustaceans and occasionally small fish.  Risso’s may be found singly but tend to form small pods.  Like other dolphins, Risso’s can form very large groups and will occasionally be found with other dolphin species in mixed groups.  They have a cohesive social structure of multiple generations that stay together for extended periods, however, in the larger schools, segregation by age and sex is seen to occur.

Risso

A third species of dolphin that is commonly seen is the Pacific white-sided dolphin.  These acrobatic dolphins have a robust body, short beak and a beautiful, sleek black, white and grey coloration with a long light colored stripe.  These animals are extremely playful and social with a love for bow riding and somersaulting in the wake of passing boats.  They feed on squid and small fish such as sardines and herring.  While hunting they are capable of diving for 6 minutes or more at a time and work cooperatively to herd fish.


As all of these avian and mammalian predators converge on the shoals of schooling fish over the canyon the sight is magnificent.  Large whales lead the parade with smaller sea lions and birds following their path both above and below the water to snap up fish disturbed by the whales.  The humpback whales arrive in Monterey bay in the spring after migrating from their winter calving grounds off Mexico where the mate and have their young.  The southern calving grounds are relatively nutrient poor and these whales arrive each year to the rich waters of Monterey Bay in order to feed.  Their feeding combines deep dives to several hundred feet deep where prey is often concentrated to lunge feeding for surface prey.  These 50 to 55 foot long whales often lead the assault on schools of small fish with a trail of diving birds and sea lions following under the water and other groups of birds following along the surface.  These large whales are also very active at the surface with a variety of spectacular behaviors including breaching, pectoral slapping, tail lobbing and spy hopping.  Many of these behaviors produce tremendous noise in the water and likely serve at least in part to signal other acoustically associated humpbacks in the area.  When the humpbacks are less focused on feeding they occasionally demonstrate curiosity towards boats swimming around and under boats while rubbing their skin against the hull and extending their huge, often barnacle-encrusted, pectoral flukes.

Spring also brings migrating grey whales through Monterey Bay.  These whales over winter in the lagoons of the Baja Peninsula and Mexico where they mate and calves are born.  In the early spring, the adult males leave first on the epic migration north, up to 7000 miles, to the Bering Strait of Alaska.  The females with calves leave later taking advantage of the extra time to nurse their growing calves in order to build their strength and to train the calves in necessary skills for the long and dangerous migration ahead.  For most of the migration, the whales follow the coast line using kelp beds to play and hide their young from predators.  However, when they reach Monterey Bay and its deep submarine canyon, the mothers and calves are forced to choose between cutting a shorter route across the canyon or taking the long, but safer shallow route around the bay.  Without the kelp beds and shallow waters to disguise the calves from listening and echolocating orcas, the calves are vulnerable.  Perhaps it is orienting or inappropriate vocalizations from the inexperienced calf that draws the hunting orcas in.  Transient orcas of California also return to Monterey Bay each spring to hunt the vulnerable and inexperienced calves.  When grey whale calves are not available in the bay, the orcas hunt seals, sea lions and small dolphins and porpoises.  In years when few grey whales are born, the sea lion population of Monterey Bay can be hard hit.

Killer whale (orca) chasing a seal

The same individual orcas are seen in this area each year and generations of their young participate in the hunting and killing of grey whale whales bring the skill set to the next generation.  Most attacks occur at the canyon edge.  If the mother grey whale detects the hunting orcas early enough she may flee with her calf to shallow water where the orcas appear unwilling to follow.

Attacks on adult grey whales are relatively rare with most attacks focused on isolating, battering and drowning the calf.  The mother grey whale protects her baby by attempting to place her titanic body between the calf and the attacking orcas and helps the baby to breath and rest between assaults by rolling on her side or back and holding the calf out of the water. However, the attacks are relentless lasting up to 5 hours or longer and the young calf is eventually separated from its mother where it is drowned or dies from a combination of internal and external wounds.  Upon dying the calf’s body sinks.  To some extent the orcas can hold the body up or drag it up from the depths in order to feed.  The tongue is usually torn out and large strips of fat rich blubber are pulled from the dead whale.  Orcas can dive down as much as 1000 feet to feed on a carcass.  Like a pack of wolves, the orcas are highly social and their is a lot of social contact and play after a successful hunt.  Tail lobbing, breaching, and even sexual displays are common in this setting.

Killer whales (orca) after a kill

As a dead whale descends into the deep water it delivers many tons of nutrients to dark regions of the abyss.  The Monterey Canyon is part of a larger, complex system of canyons extending out into the Pacific.  The greater Monterey Bay Canyon System consists of the Monterey, Soquel and Carmel Canyons.  Soquel Canyon joins Monterey Canyon about 11 miles seaward of the canyon head near Moss Landing at a depth of nearly 3300 feet.  Offshore, eighteen and a half miles southward down the canyon Monterey Canyon joins Carmel Canyon at a depth of 6463 feet.  At the head of Monterey Canyon near Moss Landing at depths of less than 6500 feet, the canyon and its tributaries tend to have steep walls and narrow floors.  The relatively flat floor is about 820 feet wide with a slight seaward slope and steep walls which average between 10 and 25 degrees but may be as steep as 35 degrees in places.

Animals that live in this harsh environment are specialized to survive in conditions of tremendous pressure and low oxygen.  Water temperatures reach about 40º F (4º C) and the pressure is 320 times the air pressure at sea level.  The deep sea is also dark with some fish, jellies and squid specialized to produce their own light while others have small eyes or none at all.  The canyon walls are inhabited by pink and white soft corals that live in 650 to 4000 feet of water using flowery tentacles to grab prey drifting by in the water column.  This is also the environment where deep sea sunstars quickly move about grasping anything it can catch with its 22 arms as well as long-legged spider crabs and predatory tunicates that resemble a submarine venus flytrap.

In the mid water, below 450 feet sunlight never penetrates and no solid surfaces exist.  a variety of strange deep water fishes hunt this region and demonstrate a daily vertical migration approaching the surface at night.  This nightly migration is probably the greatest migration of animals in the world.  The canyon floor is inhabited by a variety of sharks and their strange relatives the chimaera with their rabbit like faces and extremely ancient ancestry.  Most of the whale is eaten not by larger animals such as sharks or even by the orcas themselves but rather by smaller, more bizarre animals such as hagfish and polychaete worms.  Two such worms are specialized to digest bone.  Nothing is wasted as each specialized species takes its turn.  Although most of the food fall is not so large as this, the inhabitants of the deep depend on the “nutrient snow” that falls from the surface above.

Thus, even as life is cut short for the young whale it showers life giving nutrients onto the typically food poor sea floor which in turn supports the surface with the upwelling which provides the foundation of the surface food pyramid.  So, as life gives way to death and provides for others, spring gives way to summer bringing the ocean’s greatest inhabitant to Monterey bay with the arrival of the blue whale.  And so it continues in one of nature’s greatest and least understood places.
 

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info@markenarson.com (Mark Enarson Images) Brandt's cormorant California sea lion Monterey Bay Risso's dolphin black-footed albatross grey whale killer whale orca sea otter sooty shearwater http://www.markenarson.com/blog/2013/3/spring-in-monterey-bay Sun, 17 Mar 2013 06:18:58 GMT
Pursuit of the Natural Predation http://www.markenarson.com/blog/2013/3/pursuit-of-the-natural-predation Seal Island, a small rocky outcropping in South Africa’s False Bay, is the best place in the world to witness and photograph white sharks breaching. The white sharks launch their massive bodies from the water each winter morning in the pursuit of cape fur seals. In this location, photographers and film crews hope to capture the amazing shot of a 1-2 ton white shark flying as much as 10 feet above the water. Many of the available shots come from towing a decoy behind the boat to induce the animal to breach. If the conditions are right with limited water visibility and low ambient light, the sharks mistake the decoy for a seal and strike.

White shark breach at sunrise

Much more difficult is the goal to photograph natural breaches. The sharks hunt in a perimeter of at least several kilometres around Seal Island with the majority of predations occurring before and just following sunrise. When the conditions are perfect this can result in spectacular photographs in the warm, golden light of early morning. However, much of the action occurs in the very low morning light and during the African winter when the sharks hunt seals, most days are overcast and often rainy extending low light conditions through much of the hunting period. The predation events are distributed widely around the island and if the sharks are efficient, the predation is usually over before you can get anywhere close. Not all predations involve breaching. In fact, most often all that is seen is splashing as the sharks tail cuts across the water surface during tight turns in pursuit of an elusive seal. Moreover, most of the awe-inspiring events with acrobatic breaches occur without warning or at distances beyond photographic reach. Only in a few cases when the seal escapes initial capture and the shark is motivated to continue its pursuit for a protracted time is photography possible. Even then, timing is critical to capture the sudden breach and if the shark breaches away from the camera position, the shot is less than satisfying. All of this makes for a tremendous challenge to pursue the ultimate photo of a natural white shark predation event. A world leader in white shark breach photography; South Africa’s Chris Fallows has recently estimated that each year there are only 10 good photographic opportunities at Seal Island. Obviously it is critical to be ready when the rare and fleeting moment presents.

Seal balances on the nose of a white shark

While I enjoy photographs of white sharks breaching on decoys and present these shots on my site, photographing natural predation is my true goal. This year my trip to Seal Island was made more difficult by some of the worst weather the region has seen in more than ten years. Each weather front followed the last bringing high winds and often rain without much break in between. BBC and Discovery Channel were at the island during the same period and each suffered the same frustration of losing multiple days to weather. As much as ever, the trip came down to brief, golden moments set apart from long periods of frustration. I was fortunate to capture a series of spectacular predations on the first day of my trip. After this, it became much more difficult. Some days the sharks seemed lethargic and lone, young of the year seals were able to swim up to the island uncontested. Other days the predations seemed to move subsurface which is very unusual for this region. These predations only come to attention when a boil of blood explodes from the water. Later in the trip, the predation activity was intense with 28 events recorded in one morning. However, the weather was very difficult that morning and the sharks were ruthlessly efficient with very quick kills. One must witness such predations to appreciate that the deaths resulting from these attacks are among the quickest and most merciful of any predator in the world. No photos were possible on these frenetic mornings but as always it was an incredible spectacle to witness.

 

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info@markenarson.com (Mark Enarson Images) False Bay Seal Island South Africa decoy great white shark photography predation white shark http://www.markenarson.com/blog/2013/3/pursuit-of-the-natural-predation Sun, 17 Mar 2013 06:00:04 GMT
The Bears of Kodiak Island http://www.markenarson.com/blog/2013/3/the-bears-of-kodiak-island On a cool, rainy morning in September of 2006 I boarded a small float plane and headed out into the wilds of the Kodiak National Wildlife Refuge to photograph the world’s largest bears.  Our destination was the Aleut Island Lodge.  From here we would explore the areas salmon streams in hopes of having some close encounters with the massive Kodiak brown bears.

This island in southern Alaska is home to around 3000 bears or 0.7 bears per square mile.  This population of bears has been cut off from its kin for about 12 000 years allowing it to diverge into its own distinct subspecies.  With their rich diet, Kodiak brown bears grow to massive size standing up to 10 feet on their hind legs and reaching 5 feet at the shoulders while on all four legs.  Most of the year, the bears eat primarily grass, plants, and berries.  However, during the summer, these bears descend from the mountain forests to feast on the bounty of spawning salmon in the rivers and streams.  

Kodiak brown bear cubs embrace

The goal of bear viewing in Kodiak is to remain undetected by the bears in order to observe and photograph the animals with little to no impact.  In addition to minimizing impact on bears, this strategy also allows for some beautiful intimate photos of bears behaving naturally without any awareness of being observed.  Each time we approached a bear, the guide was careful to keep us low and positioned down wind.  As a result of this practice, the bears are not habituated to the presence of humans and typically flee if they detect their human observers.  While this is best for the bears, trying to remain undetected does increase the chances of a dangerous surprise encounter.

While most flee immediately upon sensing humans, we met one bear who was more interested in observing us and displaying his size and power.  We came across this bear while hiking through the forest.  When he detected our scent, he approached instead of heading away.  He then found a suitable tree to climb and jumped up and down on a thick, low lying branch while observing us.  The overall effect of this behaviour seemed to be to impress upon us his considerable size.

Kodiak brown bear at attention

Many of the females are accompanied by a couple of cubs.  The cubs typically stay with the mother for around 3 years before venturing off on their own.  The young bears are a fantastic photographic subject as they wrestle, play and learn to fish.  However, when dealing with cubs, it is obviously critical to remain aware of where the mother bear is in order to stay out of a very dangerous situation.  Our first encounter with a mother and cubs came early on the first day.  We were warned by the guide that the stream had high banks and any encounter was likely to be close.  As we quietly crept upstream we met a mother and cubs around the first bend.  Detection was unavoidable due to the close quarters.  Fortunately, this mother reared up on her hind legs to get a good look at us before fleeing into the underbrush with her cubs.

A much more intense encounter followed two days later while we observed a mother and two large 2 year old cubs feeding and wrestling in the shallow waters of the tidal flats.  This large mother bear forced us up onto a small rock ledge and kept us cornered while calling to her cubs.  The cubs wrestled for some time before joining their mother on the bank.  Unfortunately for us, the cubs were much more curious than the mother and approached us very close.  These cubs are very large and capable of some damage under the wrong circumstances.  The guide showed considerable skill and experience to dissuade the cubs from initiating contact while not provoking the massive mother bear into a defensive attack.

Another wonderful encounter followed early the next morning near camp as I was able to photograph two wrestling cubs from very close range.  The cubs again were aware of our presence but their curiosity kept them from fleeing as one would expect from a more experienced adult bear.  Again I was thankful for the experience and skill of the guide to maintain an awareness of the mother’s presence nearby.

On numerous occasions in Kodiak I felt deeply privileged to observe and photograph the bears under such natural and undisturbed conditions.  I feel that the resulting images capture intimate moments that I have not often seen. I hope you enjoy these images as much as I have.

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info@markenarson.com (Mark Enarson Images) Kodiak Island Kodiak brown bear Uyak Bay bear cubs photography http://www.markenarson.com/blog/2013/3/the-bears-of-kodiak-island Sun, 17 Mar 2013 05:56:50 GMT
Life in the Shadow of a Predator http://www.markenarson.com/blog/2013/3/life-in-the-shadow-of-a-predator The close presence of predators is a daily reality for many animals throughout the world.  Humans have insulated themselves from this reality by building up cities and pushing predators back into smaller and smaller natural spaces.  As a result, we have lost our sense of the natural order and we are shocked and angered when one of our own falls to a predator.  However, during winter at Seal Island, this primal struggle between predator and prey is a simple daily reality that plays out in spectacular fashion every morning.

Cape fur seals occupy this small island, near the foot of South Africa’s False Bay, year round.  Their numbers rise and fall with the influx and departure of breeding age adults and the birth of new pups.  Adult males return to the island in late October each year to compete for harems of females.  The breeding females return soon after the males and give birth to pups conceived during the previous year.  Within days of giving birth, the females mate again.  The newborn pups are about 75 centimeters long and weigh only five or six kilograms.  At about six months of age, the growing pups will join the older fur seals in taking to the sea in search of solid food.  Around the island, the fur seals hunt for small cat sharks, octopuses and crustaceans.  But, much of their fishing takes place as much as 50 kilometers out into the southern ocean.  This trip to the pelagic fishing grounds demands amazing survival skills from these small fur seals, for to reach the open ocean, they must survive passage through a gauntlet of hunting white sharks.

White shark attacking a Cape fur seal

The white sharks that gather around the island target the youngest seals.  Adult male fur seals reach lengths of 2.7 meters and weights of 350 kilograms.  Females are slightly smaller at two meters of length and 100 kilograms.  At these sizes, the powerful adult fur seals are not much smaller than the white sharks.  Armed with ferocious teeth and claws, the adult Cape fur seals are dangerous for the white sharks and they wisely focus on the smaller young seals.

Although small and naive, the young of the year fur seals are far from helpless.  They are fast and agile with keen senses to detect approaching predators.  The sharks are also well designed for the hunt with incredible speed, deceptive agility and remarkable senses.  The strategies of the predator and prey are fashioned to counter the behavior of their adversary.  Obviously the seals must get out to their feeding grounds alive, while the sharks aim to capture seals with minimal energy expenditure and risk of injury.

Seals leaving the island gather near the southern extreme of the island under the cover of darkness, joining up into groups to strike out together.  The night time departure helps to cloak the seals from the visually hunting sharks.  By gathering into large groups, the seals benefit from many eyes looking out for sharks and the numerous porpoising bodies help to confuse the predator.  As the groups depart, some seals porpoise out of the water while others swim upside down watching below for attacking sharks.  

Cape fur seals leaving Seal Island

Once the seals reach the open water, beyond the hunting grounds of the white sharks, they disperse and hunt alone.  Thus as the fur seals return from hunting, they typically do not benefit from the safety of the large group.  Furthermore, while they can time their departure from the island with the relative safety of darkness, it is much more difficult to time their long return.  As a result, some of the seals arrive back to the waters around Seal Island in the dangerous morning hours.  The twilight of early morning is the preferred hunting time for the white sharks.  During these hours, the low, early morning light does not penetrate far into the water column.  Thus, the hunting sharks are difficult for returning seals to see.  Conversely, the seals swimming above are back lit by the morning sun and quite visible to the keen eyesight of the white sharks.

Older and stronger Cape fur seals minimize the risk of this dangerous return trip by swimming along the bottom.  An adult male seal can make this final dive from as far as 800 meters from the island.  Younger seals, however, lack the strength and lung capacity for such long dives.  Thus, they must remain at the surface or return to the surface to breath in the danger zone near the island.  This leaves them vulnerable to the sharks’ devastating attacks.  Some of the youngest seals also appear naive to the dangers of swimming near the surface around Seal Island and swim the entire distance on the surface.

White shark attacking a seal in stormy weather

Attacking white sharks aim to kill the seals in a single powerful strike.  This minimizes both danger and energy cost to the attacker.  The shark swims 12 to 14 meters below the surface until it spots a vulnerable seal and mounts a well timed, explosive strike.  While the shark is much faster than the seal, it tires quickly.  The seal is slower but it can sustain its top speed for a considerable time.  Thus, stealth is essential for the shark.  The initial strike is so powerful that it often sends the white shark sailing as much as three meters out of the water.  If the seal can detect the striking shark it may be able to avoid the strike with remarkable agility.  After an initial attack misses, the seal tries desperately to stay near the safety of the shark’s tail until the predator tires and moves on to new opportunities.  For the survivor, the danger is not yet passed.  The noise of the first attack may attract other sharks and some seals must survive several attacks in order to reach the safety of the rocks on Seal Island.

Watching these predatory interactions, it is easy to forget that the seals are as young as six months of age.  The agility and skills of both predator and prey are incredible.  To watch a six month old seal acrobatically dueling with a three to four meter shark is awe inspiring.  It is tempting to think of the young seals as courageous.  But, this is not really accurate.  They are simply living the life they were allocated.  In order to feed, they must brave these attacks.  It is simply their daily reality.  Nevertheless, these young seals are amazing and admirable survivors.  While the white sharks are clearly the stars of this show.  They are some of the most amazing and powerful predators on the planet.  However, one must not forget the seals.  They are equal players in this predatory drama with incredible agility and survival instincts worthy of considerable admiration.

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info@markenarson.com (Mark Enarson Images) Cape fur seal False Bay Seal Island South Africa great white shark predation white shark http://www.markenarson.com/blog/2013/3/life-in-the-shadow-of-a-predator Sun, 17 Mar 2013 05:48:59 GMT
Amazon - The Flooded Forest http://www.markenarson.com/blog/2013/3/amazon---the-flooded-forest The density and diversity of life in the Amazon is truly staggering.  One of the first things you notice is the sounds.  There are so many birds, insects and frogs that there is a continuous symphony day and night.  By day, an extraordinary array of bird calls fills the air, many with beautiful songs.  As night falls the frogs call to prospect mates.  Through the dark hours, the cicadas produce a continuous wall of sound.

I had the opportunity to spend five days in the Amazon River basin of Peru in February of 2007.  We were based in a beautiful camp along the banks of the Maranon River, a tributary of the mighty Amazon.  The first days were spent walking through the forest searching for brilliantly colorful poison dart frogs and a fascinating array of insects.  We also explored the banks of the river photographing the many species of birds.

On the fourth day we headed up river for the Pacaya-Samiria National Reserve.  This flooded rain forest covers more than 5 million acres of the Peruvian Amazon.  During the rainy season, the waters of the Maranon and Ucayali rivers rise flooding up to 85% of the reserve.

Yellow-spotted river turtle

As we made our way up the river into the edges of the flooded forest, we were often visited by small groups of gray and pink dolphins.  I had never imagined that these amazing animals would be so frequently seen.  They are curious animals that spend a considerable time interacting and searching for fish with very little concern about the boats.  At the edge of the forest we left the comfort of the power boat for the maneuverability of a small hand carved canoe.  The canoes edge barely cleared the water as the guide paddled between the trees.  It is such a quiet, close and intimate way to see the Amazon.

In the trees above us we could hear the haunting cries of howler monkeys as they called between neighboring troops.  We carefully maneuvered our boat between thick trees and tree stumps to find our way under the calling troops.  The thick undergrowth required multiple stops to cut a path using a machete.  It was tempting to place one’s hand on the trees to help our progress until noting that the stumps were thickly covered with biting centipedes.

Centipedes in the flooded forest

After a brief sleep we returned to the flooded forest the next day under the cover of darkness to find the area’s nocturnal species.  As the sun rose we found a large group of Common Wooly Monkeys in the trees.  While their name suggests that they are frequently seen, our guides had spent their lives in this area and never seen this species before.  The monkeys were curious about our presence but spent a lot of time making dramatic displays of territoriality.  They would jump on the branches and screech while keep strong and threatening eye contact with us.  As they passed over head pieces of the vegetation came raining down upon us.  I was able to obtain dramatic images of the wooly monkeys by laying flat on my back in the bottom of the canoe with the heavy camera body and 500 mm lens balanced on my face.  

Common wooly monkey

In our brief visit we found reason to fear for the future of this critical wildlife habitat.  Weather patterns are changing and less rain falls in this water dependent ecosystem.  It is tempting to conjecture about the role of global warming and the world’s changing weather patterns.  Further, the beautiful and colorful poison dart frogs are no longer as common as they once were.  For one, unscrupulous guides have recently been combing the forest floor and removing the frogs to sell to collectors in the exotic pet trade.  Further, experts warn amphibians are vanishing around the world.  While the reasons for the mass declines in world amphibian populations are not known, it has been speculated that factors such as climate change, habitat loss and absorption of pollutants through their permeable skin many be contributing to the loss of these beautiful creatures.  

It was such a privilege to explore this beautiful region with its staggering diversity of life and critical role in the natural world.  I can only hope that it remains for future generations to appreciate and explore.

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info@markenarson.com (Mark Enarson Images) Amazon Maranon river Pacaya-Samiria National Reserve Peru centipede common wooly monkey howler monkey river dolphin http://www.markenarson.com/blog/2013/3/amazon---the-flooded-forest Sun, 17 Mar 2013 05:43:10 GMT
Denali - Alaska's Autumn Jewel http://www.markenarson.com/blog/2013/3/denali---alaskas-autumn-jewel For a brief moment each autumn, a blanket of spectacular color falls across Alaska.  The progression begins as the underbrush lights in a blaze of reds and orange and continues in the coming days as waves of yellow spread across the trees.  The moment seems so brief and magical as the color fades in only a few days.  While it lasts, nature seems wrapped in a colorful drape.  The explosion of color comes at time of year when animals are making essential preparations for the rapidly approaching brutality of the Alaskan winter.

One of the best places to see this beautiful fall transition is in central Alaska’s Denali National Park.  This six million acre park was established in 1917 to protect the populations of large mammals living in the shadow of North America’s tallest mountain, Mount McKinley.  This towering peak is also known by its aboriginal name, Denali, meaning “the High One” in the language of the Athabascan native people.

Autumn in Denali National Park

The subarctic wilderness in Denali National Park is cloaked with a wide variety of plants, specially adapted to surviving the long and bitterly cold winters.  The high grounds support flowering plants as well as many species of mosses, lichens, fungi, and algae. Along the rivers and valleys there is scant tree growth.  These sparsely treed regions are known as taiga.  Drier areas are populated by white and black spruce, quaking aspen, paper birch, larch, and baslam poplar.  Moist regions grow sedges and cottongrass as well as willows and alders.

A total of 37 species of mammals live in the park as well as 156 species of birds.  The park’s “big 5” are the grizzly bear, wolf, caribou, moose and Dall’s sheep.  Four of the animals are widely distributed through the park and are commonly seen.  Wolves are smaller in numbers and are much harder to spot.

Dall

During the short autumn season, the park’s caribou herds begin to migrate westward across the park.  These herds are vulnerable to packs of wolves as well as grizzly bears that are trying to pack on precious fat reserves in order to weather the coming winter.  One herd of caribou that I saw passing trough a low valley was thrown into a panic when the caught the scent of a grizzly perched high on a ridge above the dry river bed.  Growth of the males’ antlers peaks in autumn.  These imposing weapons allow the males to battle for control of harems of females for mating.

Moose spend the autumn months foraging on the colorful willows that carpet the low areas of the park.  This season is the rutting time for moose.  Large males will tend to control harems of females while groups of younger males move together.  Moose is active in the cold, early morning hours and move deeper into the brush to rest during the middle hours of the day.  Many moose can be seen along the first 15 miles of the park road where public vehicles are allowed to drive.

Moose resting in the foliage

Between 12 and 18 packs of grey wolves live in the park, totally about 100 animals, but they are uncommonly seen.  Each pack has an average of eight to ten members but the largest pride recorded in the park had 27 wolves.  The wolves hunt in groups and share food amongst members of the pack.  They hunt up to 10 hours a day in order to obtain the two to four kilograms of meat that each member need each day to survive.  These flexible hunters will stalk mice and ground squirrels as well as larger prey such as caribou, Dall’s sheep and moose.

Grizzly bears in Denali National Park are omnivorous but primarily subsist on berries and other vegetation.  As a result, these bears are smaller than other coastal brown bears in Alaska that live on a rich diet of salmon.  As a result of their leaner diet, grizzly cubs in Denali National Park usually live with their mothers for a longer period before striking out on their own.  While these bears eat primarily vegetation, they are ever ready to hunt and play a significant role culling the herds of caribou, sheep and moose.  On one visit to the park, I saw a mother grizzly and her grown cubs attacking a beaver lodge hoping to feast on the beaver.  Two bears dug at the top of the lodge while another waited at the exit of the lodge hoping to ambush the escaping beaver.  Fortunately for the beaver, lodges have more than one exit and it was able to escape while the bears were still attacking the lodge with vigor.

Grizzly bears in the bright autumn colors

Photographic opportunities in the park are spectacular in the colorful autumn days.  Denali National Park is a large and beautiful park with many large animals.  However, in such an expansive park, the animals range widely requiring extensive travel to find the best opportunities.  Further, the park is admirably operated by the US Parks Service.  With a tremendous number of annual human visitors, the Parks Service does a very commendable job of keeping the park wild and preventing close interaction between the visitors and the wild inhabitants.  This is a critically important role of the officials but it makes wildlife photography difficult.
 

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info@markenarson.com (Mark Enarson Images) Alaska Dall's sheep Denali National Park autumn caribou grey wolf grizzly bear moose http://www.markenarson.com/blog/2013/3/denali---alaskas-autumn-jewel Sun, 17 Mar 2013 05:36:38 GMT
Monterey Bay Orca Attack http://www.markenarson.com/blog/2013/3/monterey-bay-orca-attack Spring is a time of intense predation in the waters of California’s Monterey Bay.  After months of fasting in warm southern waters, numerous humpback whales fed on large schools of anchovies near the submarine canyon.  On the first two days of our trip there were humpbacks in every direction, up to 30 each day.  Our fish finder suggested that the anchovies began at about 100 feet and went right to the bottom at 280 feet extending for hundreds of yards.  The immensity of this school seemed beyond imagination.  Groups of sea lions dove and surfaced in unison feeding on the school as birds circled overhead and mighty humpbacks dived into the feast.

On the third day, things began differently as we headed out from Moss Landing.  The sky was covered in thin grey clouds and the water was flat like glass.  Whereas the area had been alive with hundreds of California sea lions, birds and humpbacks in the previous days, that morning all seemed very quiet.  We met a lone humpback as we left the harbour.  This whale was swimming lazily near the boat without actively feeding.  We soon came across a second pair of humpbacks sleeping at the water surface.  They alternately floated and pushed themselves forward with slow beats of their mighty tails, half of their brains remaining alert to watch for danger and to drive them back to the surface to breath.  The calm was peaceful but eerie compared with the vigorous feeding of the preceding days.  

I had come to Monterey hoping to photograph transient orcas hunting grey whale calves as they migrate with their mothers to northern waters.  The mothers and calves must make this long and dangerous 6 000 mile journey to feed in the rich arctic waters after the calves are born in the warm but nutrient poor waters of Mexico during the winter months.  Through much of the journey, grey whales remain in the relative safety of shallow nearshore waters.  However, the whales reach a point of particular vulnerability when they reach Monterey Bay with its deep and complex submarine canyon system.  While in nearshore waters, the grey whales can hide their infants in kelp beds that help to cloak the calves and disguise them from the echolocation of hunting orcas.  Upon reaching Monterey Bay, the grey whale pairs either follow the long but comparatively safe path around the bay or cut directly across the deep canyon.  Some have proposed that it is the young and least experienced mothers that will chance this direct and dangerous path across the deep waters of the canyon.  Most attacks occur at the canyon’s edge.  It has been suggested that the grey whale’s orienting vocalizations or even inappropriate vocalizations by the calves near the canyon may provide a hunting advantage to the passively listening orcas.  Orca attacks on adult grey whales are rare.  Most predation is focused on the calves which are an attractive prey if they can be separated from their mother’s protection.  If the young whale can be separated from its mother it can be fatigued and drowned by the orcas in a brutal struggle that can last 5 hours and longer.

Killer whales (orca) attack a grey whale

Unfortunately, few if any grey whales had yet been seen this April and word from researchers in Mexico told that the grey whales were late in leaving their southern calving grounds.  Hope renewed with word that a single mother and calf had been sited on the edge of the bay the previous day.  

As we left the sleeping humpbacks, our spotter sited the tall dorsal fin of a large bull orca in the distance, perhaps a mile and a half ahead.  The boat sped ahead to join the animal.  When we approached it was clear that there were an unexpected number of orcas spread around the mouth of the bay.  At first it seemed that a group of residents may be coming through but closer examination of the saddle patches confirmed that these were transients.  The resident and transient orca populations seem to have diverged a hundred thousand years ago developing differences in social structure as well as diet and hunting strategy.  Resident orcas live in larger, life long groups of a mother and her generations of offspring.  These highly vocal orcas seem to feed entirely on fish.  Transient orcas on the other hand have a more fluid social structure and silently hunt primarily mammalian prey in smaller groups, vocalizing only after or between hunts.  

As we approached, the transients milled around in small groups without apparent direction or purpose.  Suddenly, the orcas came together into tight groups and began to travel rapidly to the southwest.  They were split into two groups that travelled close together.  Our spotter counted 23 individuals including two large bulls.  Their path led towards the blows of great whales in the distance.  It appeared that they may be hunting the mother and calf sited the day before.  However, the orcas changed direction several times cutting long transects across the bay clouding our perception of their destination.  Nevertheless it seemed that they must be hunting.

In the late morning we had to return to port leaving the hunters.  It was disappointing to pull away as, with the intense change in the mood of the bay, it seemed clear that something was soon to happen.  However, an hour and half later, our boat sped back towards the edge of the submarine canyon, returning to the spot where we had observed the humpbacks feeding for the past 3 days.  As we approached we were met with frantic activity and large splashes.  The orcas had found the mother and her calf.  Even from a distance it was easy to see the aggressive passes of the large orcas trying to cleave the calf from its mother in order to drown it.  Upon detection by the orcas, mothers and their calves will typically dash towards the safety of shallower waters.  The orcas generally appear unwilling to follow their prey into shallow waters less than sixty feet deep.  This pair had made their way along the canyon’s edge towards the beaches near Moss Landing where we found them again.

 

Grey whale calf seeks protection

As we approached we saw the mother lying on her side holding the calf above the water lying across her exposed flank.  This behaviour helps to lift the calf away from the constant assaults for brief moments of reprieve.  Again and again the orcas hurled themselves at the calf knocking it from its position of relative safety.  The calf appeared strong but the red stain of blood was evident in the spray coming off the calf.  For 20-30 minutes these attacks continued.  At this point a pair of humpbacks appeared in the mix.  The humpbacks began to pass between the grey whales and their attackers close enough to touch the greys.  On several occasions the humpbacks struck the attacking orcas with their great pectoral fins and appeared to swipe at the attackers with their tails.  The humpbacks repeatedly passed over and around the greys but the orca attack was relentless.  As the minutes passed, several more humpbacks appeared.  At this point, strange and haunting humpback vocalizations began to emanate from the sea as the humpbacks would surface.  While the meaning of these vocalizations is impossible to know, one could feel the distress of these animals in the presence of the hunting orcas.  Similar “wheezing” blows have been described previously during an orca attack on humpbacks in Canadian waters and these differ markedly from their vocalizations under normal circumstances.  It seems possible that these sounds function as a humpback distress call and may have contributed to the arrival of additional humpbacks.  As more humpbacks appeared, physical encounters began to occur between humpbacks and orcas away from and surrounding the main struggle involving the calf.  Much was unclear due to the subsurface nature of the events but the orcas and humpbacks would come together with much splashing and the appearance of tails and pectoral fins above the surface.  At one point a large bull orca was engaged with two humpbacks away from the main battleground.

Wounded grey whale calf
The action was intense with large sprays in which one could appreciate the backs and dorsal fins of greys, humpbacks and orcas in very close proximity.  As time came for us to head back to port, groups of orcas continued to hit the calf as its mother tried to position herself between her baby and the attackers and to strike at the orcas with her tail.  The calf still had energy enough for shallow breaches but the attacks seemed without end.  As we pulled away an orca leapt onto the back of the calf as it surged forward trying to escape.  Splashes and struggles continued in the distance as the boat pulled away.

As we returned to the harbour, both the outcome and the significance of what we had seen were still unclear.  What was clear was that such involvement of humpback whales in the predatory interaction between orcas and grey whales was something that none of the observers had seen or heard of before.  While only a small number of predatory attacks by orcas on humpbacks have been described worldwide in the past 200 years, in fact, up to 20% of humpbacks on the California feeding grounds bear rake marks from the teeth of orcas.  However, I can not find any published description of an event like the one we witnessed.  It is difficult to be certain of all that transpired due to the cryptic nature of the watery environment but it is absolutely clear that a group of humpback whales became closely involved in this predatory event, placed themselves repeatedly between the attacking orcas and the vulnerable grey whales and had many dramatic and close interactions with the orcas throughout the event.  While it is possible that the humpbacks themselves were independently under attack, they seemed to approach the site of the attack from elsewhere putting themselves into danger.  The orcas’ energies seemed focused on the grey whale calf and the humpbacks placed themselves in a position near to the grey whale mother and calf increasing their personal vulnerability.  Further, we did not see any direct assaults on the humpbacks and while both the mother grey whale and calf had wounds with exposed blubber, none of the humpbacks had any obvious injuries.

The next day began with word that the grey whale calf was seen escaping from the previous day’s attack.  It is easy to speculate that the seemingly heroic involvement of the humpback whale may have evened the score enough to allow the calf’s survival.  Expectation was high as to what the bay might hold this new day.

We set out again into Monterey Bay passing feeding humpback whales on the way out.  As we reached the centre of the bay, the fins of transient orcas again came into view.  As we approached we found that they had surrounded a lone grey whale calf, isolated from its mother.  The calf was swimming slowly spending much of the time lying on its side.  In this position, we could clearly see the extensive wounds on the baby’s flukes and exposed side.  As the boat approached, the calf sought shelter directly under our boat.  A large bull orca vigorously and repeatedly tail slapped in the direction of the boat and the whale cowering under it from mere feet away.  The orcas did not appear particularly dissuaded by the boat and continued to rush under the boat to harass and attack the calf.  This put our boat in a particularly dangerous position.  As the baby whale floated out from under the boat, it gazed upwards making direct eye contact.  This was a sad and striking moment as multiple orcas made passes at it only feet off the side of the boat.  Carefully we moved our boat away to a safer position and allowed the natural event to continue without interference.

Dying grey whale calf

Where was the baby’s mother?  It seems very likely that these were the same mother and calf from the previous day.  Had they finally been separated?  The answer it would seem was likely more sinister.  The orcas continued their assaults on the baby, repeatedly ramming it in coordinated waves for several minutes.  The orcas then moved off several hundred yards to the south where they circled taking dives repeatedly into the same area of sea.  As the orcas left the wounded baby, instead of fleeing, the baby swam slowly towards the orcas.  As we approached this area with our boat, the unmistakable smell of blubber filled the air.  It seems that a whale carcass was likely lying below the surface.  After a kill, the carcass of an adult grey whale sinks to the bottom with the orcas diving as much as 1000 feet in order to feed.  It is likely that the baby felt compelled to return to the site of its dead mother.  Without her, it had little direction or chance of survival.  Having been recently born in the warm waters of Mexico, this baby had never made the northern migration before and surely was not yet weaned.

Around the site of the previous kill, the orcas behaved like a pack of wolves after a successful hunt.  There was a wide variety of social behaviours mixed in with the subsurface forays for feeding.  The orcas breached and tail slapped around the site.  After swimming weakly towards the kill, the baby was not seen again.  We could not be sure whether the baby was killed subsurface or whether it simply swam away.  If it swam on, the hunters would have easily been able to reacquire the baby and kill the helpless and weakened animal later.

Killer whales (orca) after the kill

It is chilling to conjecture about the events that passed between the two predation events.  The mother and calf seemed to have escaped late in the previous afternoon but may have been gravely injured and unable to make much progress out of the bay.  What a long and terrifying night it must have been before the final kill.  Might the injuries that the mother had accumulated in defence of her baby have finally led to her demise?  What a sad and compelling sight to see the baby robbed of its caregiver, alone, directionless and helpless against the predators.

We returned to the same site several hours later and a large oil slick had spread across the surface of the water giving testament to what had come before.  The orcas were now in a different behavioural state moving about in small groups without urgency.  It seemed that this particular tale had come to a sad and compelling conclusion.

The next and final day was very quiet on the bay.  We encountered no whales on our travels out into the centre of the bay where the carcass remained below the surface.  There we found the orcas still circling the hidden remains, intermittently diving to feed.  The oil slick remained across the water surface.  After several hours of feeding, the orcas left en mass, heading with speed to the northwest to parts unknown.

As we headed back to Moss Landing and our time in Monterey Bay came to an end, we encountered three humpback whales that were game for a friendly encounter.  As they frolicked around and below the boat looking up at their human observers, it seemed a quiet, peaceful end to the gripping and bloody events that we had witnessed.

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info@markenarson.com (Mark Enarson Images) Monterey Bay grey whale humpback killer whale orca predation whale" http://www.markenarson.com/blog/2013/3/monterey-bay-orca-attack Sun, 17 Mar 2013 05:31:47 GMT
Saving the Amazon Through Tourism http://www.markenarson.com/blog/2013/3/saving-the-amazon-through-tourism In January of 2008, I had the great privilege to visit the Ecuadorian Amazon at the Napo Wildlife Center Eco-Lodge.  This unique lodge, nestled along the banks of Lake Anangu in the Yasunì National Park.  This park is an important UNESCO Biosphere Reserve and the largest tract of tropical rain forest in Ecuador.

This area of the Amazon is under constant threat from deforestation, bush meat hunting and habitat destruction brought about through the actions of major international oil and gas companies.  The lodge was created in 2003 through the combined efforts of the local, indigenous Anangu Quichua Community and international sponsors.  

Prior to the creation of the lodge, the Anangu people were extremely poor.  The tribes people had to travel many miles in order to earn small wages to support their families.  This greatly impacted tribal life, as many of the adults had to spend large amounts of time far from their families.  With the help of international benefactors, these people used the best local knowledge and the best eco-sensitive technology to create a means of showing outsiders the wonders of the Amazon in a low impact way, while helping the people to protect their local environment.  The international interests kindly gave over ownership of the venture and today it is 100% owned and operated by the people from the nearby village.

Black caiman

The resulting lodge is beautiful, welcoming and extremely well operated.  The guides and staff are extremely friendly and welcoming, and the facilities are luxurious.  These people demonstrate a deep love of the area and its inhabitants.  They apply strict rules to keep the tourist activities from having significant impact on the animals living around the area.  

Each day, I was woken by the haunting calls of troupes of nearby howler monkeys.  After eating, we set out under the cover of darkness in dugout canoes to explore the surrounding forest by water.  A myriad of tropical birds live in the surrounding trees while troupes of squirrel monkeys wind their way across the tree canopy above.  Down the river, a short paddle away, large, mixed, flocks of colorful parrots, parakeets, and parrotlets feed on clay deposits which help to detoxify chemicals found in the seeds that make up their diet.  Along the way to these clay deposits, a local farm provides habitat for groups of tiny pygmy marmosets, the world’s smallest monkeys.  These tiny primates live in large family groups, high in the trees, descending to feed on sap from the tree trunks.

Parrots, parakeets, and parrotlets

The lucky visitor has opportunity to spot small groups of giant otters the fish in the side streams near the lodge.  These otters appear to be very shy near the boats and the ethics of the local guides forbid following them if they choose to flee.

Later at night, there is opportunity to head out onto the lake with handheld lights to spot the glowing eyes of black caimans in the water.  Although these relatives of the crocodile grow to large size, I saw only small juveniles during my forays out into the darkness.

There are many opportunities to spot monkeys, otters and birds, but, any trip to the Amazon is woefully incomplete without stopping to appreciate the smallest inhabitants of the region.  The insect life hiding on and under the low lying foliage is incredible in its variety and imaginative manifestations.  Many species of bats sleep along tree trunks during the day and hunt fish and insects under the cover of night.

Squirrel monkey

The Amazon is one of the truly great wonders of the natural world.  Every nature lover must visit this region at some point in their life.  The threats to the survival of the great forest grow every year.  It is heart warming to meet local people who are committed to working toward its survival.  The Anango people are now meeting with other local peoples to teach them to build and run their own ecotourism operations.  As more local groups commit to such ventures, hopefully the tide will turn from exploiting the forest for bush meat, oil exploration and farm land and turn to towards sustaining the forest for future generations.  I encourage you to support such ventures if you plan to visit the Amazon.

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info@markenarson.com (Mark Enarson Images) Lake Anangu Napo Wildlife Center black caiman ecotourism giant otter howler monkey parakeet parrot parrotlet pygmy marmoset squirrel monkey http://www.markenarson.com/blog/2013/3/saving-the-amazon-through-tourism Sun, 17 Mar 2013 05:19:38 GMT
The Sailfish of Isla Mujeres http://www.markenarson.com/blog/2013/3/the-sailfish-of-isla-mujeres In March 2010, I traveled to Mexico where I had an opportunity to swim with and photograph the ocean’s fastest animal - the sailfish.  Once an exclusive encounter for only the most elite underwater photographers, more and more great photos are emerging from the spectacular bait balls that occur each year off Isla Mujeres, Mexico every January to March.  I was lucky to be invited along by Chris and Monique Fallows on this photographic expedition.  I have been planning to photograph sailfish for a few years.  Chris had been excited about the prospect since being shown footage by BBC photographers visiting Seal Island.

These spectacular fish gather off Isla Mujeres to hunt sardines.  Great schools of sardines move through the area at depth but group into tight balls when threatened by predators.  These balls are chased by the sailfish who dart into the ball of fish, slashing with their serrated bills, separating wounded fish from the group.  These wounded fish are then quickly picked off by the agile predators.  Occasionally these assaults separated small groups of sardines from the ball and then the action is explosive with multiple sailfish capturing the isolated fish.

While swimming calmly or chasing from a distance, the sailfish are sleek and silver with only a subtle hint of vertical stripes along their sides.  However, when excited, the sailfish raise their spectacular first dorsal fins (sails) and explode with color.  As they change color, flashes of purple and blue appear along the sail, with horizontal stripes of green along their flanks.  As the transformation completes, their bodies turn bronze, with vertical electric blue stripes along the sides.

Brightly colored Atlantic sailfish

In order to photograph these events, the crew of the boat will watch for groups of birds following a bait ball from above.  Upon finding and approaching a bait ball, the speed of the chase is considered.  Some pursuits are very fast and there is little sense in entering the water.  Generally, a bait ball with a slower pace is chosen.  The boat draws close to the bait ball and the photographers jump into the water with snorkels and fins.  It takes a moment for the bubbles to clear and to orient to the underwater surroundings.  In some cases the pursuit is coming past you as you enter.  In other cases, it is necessary to raise your head in order to locate the birds.  This gives you a direction to swim.  As you approach, the darting movements of the sailfish come into view.  Anywhere from a few to nearly one hundred sailfish can be found attacking a single bait ball.  Often, pursuing the bait ball means snapping a few photos before swimming with all you’ve got in an effort to keep up.  This may require returning to the boat and speeding forward for a new drop position for a few successive efforts.  Sometimes as the ball either splits or shrinks with more and more sardines falling prey, the pursuit will slow or even stop.  In these cases, the ball of sardines will swim back and forth or in circles, contained and surrounded by attacking sailfish.  These are the best opportunities for photos.

Once the bait ball stops, the action can become intense around the divers.  Sardines separated from the group often seek shelter under and against the divers.  It is tense as the sailfish swim at arms length pursuing the sardines under and between divers.  On one occasion I had to duck as the sailfish’s bill went over my shoulder.  While there are moments of concern for your own safety, it is hard to not feel some sympathy for the terrified sardines as well.  On more than one occasion, I had a sardine bumping against my limbs are hiding under my camera housing as I swam in pursuit of the bait ball.  In one instance I was able to bring a sardine right back into the relative safety of the bait ball after it swam with me for ten minutes or so.

Atlantic sailfish attacking sardines

Sea conditions and water clarity varied considerably from day to day and even from hour to hour.  Wind is a significant consideration during these months of the year and often the swells and wind waves filled our snorkels with unexpected gulps of sea water.  Backscatter provided another significant challenge.  This is the phenomenon where light from the camera strobes illuminates debris in the water producing the appearance of a snow storm.  The seemingly clear pelagic water was full of particles, including the scales of sardines killed by the gangs of sailfish.

It was an exhilarating experience and I hope that the photos communicate the beauty and drama of these events.  We were privileged to benefit from the expertise of the crew of Keen M International.  This company has played host to the world’s greatest underwater photographers and film crews.  Many dates are taken up by professional photographers, but inquires can be made at http://www.islamujeressportfishing.com/index.html.

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info@markenarson.com (Mark Enarson Images) Atlantic sailfish Isla Mujeres Mexico photography predation sardine http://www.markenarson.com/blog/2013/3/the-sailfish-of-isla-mujeres Sun, 17 Mar 2013 05:16:41 GMT
Raising Baby Cheetah Style http://www.markenarson.com/blog/2013/3/raising-baby-cheetah-style For a cheetah on the Serengeti plains, life is hard.  These graceful predators are killed and displaced by larger predators and the odds of survival are heavily stacked against them.  As a result, the population density of cheetahs in the Serengeti is low.  Estimates in the 1990s put the number of cheetahs in the whole of the Serengeti at 500 to 900 individuals compared with about 2500 lions and 5000 spotted hyenas.

Cubs are born blind and defenseless.  Usually two to three, 1.5-2 lb cubs are born with each litter.  Their eyes open at 4-10 days of age and teeth appear at 3 weeks.  They spend the first 2 months of their lives hidden in a lair.  During this time mortality is very high with 72% of entire litters dying before ever emerging from the lair.  Lairs are simple, consisting of an area of flattened vegetation in a secluded area protected by an area of dense or high cover.  A lair must be well hidden from predators and provide shelter from the elements.   Survival of the cubs depends primarily on remaining hidden from predators but the ability of the lair to protect the cubs from the elements is also critically important as the cubs have limited ability to maintain their body temperature and in the cold and wet they may die from exposure.

Predation is the major cause of death for young cubs and the mother must take great care to prevent lions and hyenas from finding her lair with its defenseless cubs.  Lions are known to locate lairs by observing cheetah mothers sit up in the marsh or bush where the cubs are hidden or by seeing the mother entering or leaving the lair.  Lions then rush at the family of cheetahs and kill the cubs with a bite through the neck or skull.  A mother cheetah has no defense against the much larger cat.  As a result, mother cheetahs must be sly.  Mothers often return to the lair after dark which helps to prevent the predators from finding the lair.  Cubs are also moved to new lairs approximately every 5 days.

Baby cheetahs on the Serengeti plains

In the wild, mother cheetahs may not eat for several days following delivery of the cubs and may spend virtually all of that time with the newborns.  After this the mother must leave the cubs for lengths of time to hunt in order to meet the energetic requirements of lactation.  It is normal for cubs to be left alone in the lair for hours at a time.  Mothers spend an average of 9 1/2 hours away from the cubs on days when they hunt.  They are conscientious parents and almost always return to the lair the same day even if they fail to capture prey.  However, in some cases a mother cheetah will abandon her cubs if she fails to catch enough food or must range great distances in pursuit of gazelles.

Cubs grow at a rate of about 1 1/2 oz per day (44 g/day in males and 41 g/day in females).  The growth rate depends on the mother’s nutrition and growth of cubs drops off if maternal food intake decreases below 3.3 lb (1.5 kg) per day.  Conversely, growth rates do not increase if the mother consumes more than this threshold per day.

Surviving cubs emerge from the lair at about 8 weeks of age.  Predation results in considerable mortality at this point.  A further 53% of cubs are killed in the first month to six weeks after they leave the lair.  While these young cubs are still extremely vulnerable, some are able to survive an attack by scattering and hiding from the predator and later rejoining their mother.  Cub mortality drops off somewhat in the 4th month of life as the cubs are usually fast enough to outrun their predators.  However, at least 41% of cubs alive at 3 months of age subsequently die.  Overall, by the time the cubs reach independence by 18 months to two years, there is only a 6% chance of survival.

When watching a mother cheetah with her young cubs, one is struck with a mixture of admiration and sympathy.  The adult cheetah must contend with finding and catching elusive prey while keeping reigns on her playful cubs all the while watching for danger.  Meanwhile, the cubs are extremely playful without any apparent appreciation of danger or the consequence of their actions.  After a long day of travel to find suitable prey, I observed a mother cheetah and her two young cubs approach a herd of Thomson’s gazelles, a favored prey.  Initially the cubs remained hidden well behind the mother as she slowly and patiently stalked closer to the herd.  Her approach required considerable patience and care as the cover was minimal and if the gazelles were alerted to her presence all hope was lost.  The cubs played their role well initially by staying in hiding.  However, eventually the cubs appeared to grow restless and came bounding after their mother and jumped on her.  This occurred repeatedly over a couple of hours and each time the mother cheetah patiently played with and lovingly groomed the cubs before continuing the careful stalk.  I was mystified by her gentle grace with the cubs.

An alert cheetah and her cubs

This time of life after the cubs leave the lair and become more active brings many new challenges for the cheetah family.  There is a continual need to find and kill prey all while nearby to other predators that would kill the cubs if given the opportunity or steal the prey item if the predation is revealed.  Kills are stolen by regularly by lions, hyena and leopards.  As mentioned previously, the mother must maintain a regular nutritional intake in order to meet the demands of the growing cubs.  Observations of cheetah families suggest that mother cheetahs are vigilant for potential prey during a hunt but her vigilance turns to potential danger once a kill is made.  Both of these forms of vigilance are observed to decrease as the cubs grow older.  While young cubs nurse from their mother they will also eat meat from the time the emerge from the lair to follow their mother.  Cubs are weaned at about 14 weeks of age.  After this time the mother cheetah invests less time in hunting as she is relieved of the energetic investment in lactation.  

As a cheetah family travels across the savanna, the cubs regularly stop to wrestle, chase and explore novel objects in their environment.  It is a seemly carefree time for the cubs who appear to have difficulty discerning what objects are dangerous and what is harmless.  Cubs have been witnesses running towards a lioness while behaving defensively with hissing or flight from harmless birds.  A mother cheetah appears to give the cubs considerable freedom to play and will occasionally join in on some gentle wrestling and grooming at rest stops but all the while she must remain alert from danger that is never very far away.  This play chase contributes to development of all of the skills that the young cheetahs need for successful hunting.  At four months of age the cubs may pursue small animals that are not normal cheetah prey.  By five months they show more interest in pursuing larger animals.  At this age the calves will often chase down a gazelle fawn that has been subdued and then released by the mother for them to recapture.  At 6-7 months of age, the cubs can sometimes capture hares without assistance from the mother.  However, they are not yet able to capture a gazelle but will assist in killing a gazelle caught by their mother.  By 11 months the cubs will participate in stalking and chasing gazelles but most of the hunts are initiated by the mother.  At this stage, a cub will often jump to soon in transitioning from stalking to chasing the prey resulting in the gazelle being scared away.  Around this time, however, a cub may occasionally will succeed in hunting and they demonstrate the fundamentals of hunting that they will need soon as they become independent of their mother.  During the initial days of hunting alone, most young cheetahs are still inexperienced hunters but the skills gained from their mother have set them on a path to becoming skilled killers.

Baby cheetahs under mother

The average age at which cubs leave there mother for independence is 18 months.  After leaving their mother’s care, siblings remain together as a group for an average of 6 months.  After this time all female cheetahs become solitary except for raising cubs of their own.  Males on the other hand often stay together for several years and some male sibling live and hunt together for life.  After obtaining independence, 50% of male cheetahs are killed as a result of competition and conflict over territories.

Production of another litter depends on the success of rearing the previous cubs.  Mothers who successfully raise their cubs to independence will often conceive before the previous litter has left, however, they rarely give birth to the new cubs until after the family splits up.  A mother who loses her cubs will often search for and call for their cubs for several days following the death or disappearance.  She will then mate on average within 3 weeks of losing a litter.  Cheetah females cycle every 12 days and conceive readily after losing their young.  Some individuals conceive at first estrus just 2-5 days later.  Gestation is only 93 days and the mean time from the death of a litter to next successful conception is 18 days and to the next birth is only 111 days.  Thus, while cheetah mothers are dutiful and conscientious, nature has provided the means to rapidly replace lost cubs which is reasonable given the staggering mortality of young cheetahs.  In spite of the long odds which face the cheetah individually and as a species, most adult cheetahs are able to replace themselves in the next generation as on average two of their cubs will eventually reach reproductive age.  Life is not easy for the cheetah and their numbers remain at an endangered level.  However, through biological adaptation and and the continued efforts of diligent cheetah mothers, the species continues to hunt the plains of Africa as it has for many thousands of years.

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info@markenarson.com (Mark Enarson Images) Serengeti cheetah cub hyena lion http://www.markenarson.com/blog/2013/3/raising-baby-cheetah-style Sun, 17 Mar 2013 05:10:29 GMT
Seasons of the Great Bear http://www.markenarson.com/blog/2013/3/seasons-of-the-great-bear The year begins for a Kodiak bear deep below the Alaskan snow.  Within the den, a Kodiak bear spends the winter months in hibernation.  During these months, the hibernating bear does not eat, drink, defecate, or urinate.  As winter progresses, the bear’s body temperature drops slowly reaching a low of 12 ° C (21.6 ° F) below its normal active temperature.  Through some miraculous adaptations, the bear is able to minimize toxic waste products in its system by reabsorbing toxic protein breakdown products through the walls of the bladder and bowel and forming new tissue from these simple building blocks.  This biochemical marvel also mitigates much of the need for urination and keeps the bears body fluids in perfect balance through the cold winter months.  The bear’s heart rate also slows from a normal rate of 40 beats per minute to as little as eight beats per minute and then back to 40 for a short time each day due to spontaneous arousal mechanisms.  Oxygen consumption drops by 50% or more and carbon dioxide production decreases.  Somehow through these mechanisms the bear’s muscles do not waste; its bone remain mineralized and strong.

Winter dens are constructed at elevations of 100 to 3300 feet above sea level with most around 1800 feet along the steep slopes of Kodiak’s mountain sides.  They are typically sheltered by deep snow cover which helps to insulate the den against the cold.  The dens have a single entrance and a single chamber which is lined with branches.  Some are built with a tunnel and others open directly into the sleeping chamber.  Entrances are arch or oval shaped and average three feet in diameter and the chamber is arch or cone shaped averaging 5 feet in width, 7 feet in length and 4 feet in height.

Cubs are born in the den between January and February.  At birth they weigh less than a pound.  Their eyes are closed and they have little hair.  The mother bear wakes from her stupor briefly to give birth, eat the placenta and clean the newborns.  The typical litter size is 2-3 cubs with the number of cubs being determined by the mother’s nutritional status.  The cubs themselves do not hibernate but stay nestled into their mother, nursing and putting on weight.  The mother’s milk is from 25-33% fat, exceeded in richness only by that of some marine mammals.  By the time spring arrives, the cubs will weigh 15-20 lbs.

 

Baby Kodiak brown bears learning to fish

This young bear family will emerge from the den in April.  The first few days out of the den are filled with laying around, snoozing, and nursing as the mother’s hibernation state slowly wears off.  These first days are spent in the immediate vicinity of the den.  As the winter somnolence wanes, a serious hunger awakens in the mother.  She must eat to regain the weight lost during the hibernation months.  In the high mountain environment, snow still thickly covers the ground and their is nothing available to eat.  If the bears are lucky, they may chance upon the carcass of an animal that did not survive the harsh winter.  This protein is a tremendous find for a hungry bear.  Otherwise the bear will use her knowledge of seasonal food availability as well as her incredibly acute senses to locate food sources.

Most of the bear’s diet during this time is made up of a variety of plant species.  The bears eat each type of plant when it is rapidly growing during the spring and early summer.  This is the time when the plant is at its most nutritious.  Nevertheless, the overall nutrition of the plant is low when compared to its weight and bulk.  Therefore, the bear is highly attuned to any opportunity to scavenge the high energy protein of an animal.  Even then, high energy internal organs are eaten first.  The bears of Kodiak feed predominantly on high energy sedges in the spring which grow on the hillsides.  These sedges emerge earliest after the snow melts and store large amounts of energetic carbohydrates in their roots and rhizomes.  During this time, the cubs have a rapid growth rate and place heavy nutritional requirements on their mothers who in turn must make up not only for the nutrition lost over the winter but also for the energy passed on to the cubs through their milk.

Kodiak bears are among the largest bears in the world.  While some exceptional individuals must rank as the largest bears on the planet, the average size of a polar bear remains larger.  A large male Kodiak bear can reach 10 feet tall when standing on its hind legs and five feet tall when on all fours.  They reach 1000 lbs in weight and even higher in some cases.  Females are 20% smaller and 30% lighter than their male counter parts.

After grazing in the high mountains for 5-6 weeks, the bears abruptly descend for the arrival of the first spawning salmon as well as the ripening of highly nutritious berries.  As these lowland foods become available, the highland sedges are dropping in nutritional value and becoming less palatable.  By mid-August the bears are less frequently found along salmon streams and spend their time hunting the midlands for berries.

Kodiak brown bear

Mating season also takes place in the late spring and summer on Kodiak.  Males and females avoid each other for much of the year, due in part to their solitary nature and also to the threat posed by males to the young cubs.  Kodiak bears are induced ovulaters and a male will try to kill the cubs sired by another male in order to bring a female into estrous.  Over 25% of cubs die before reaching independence at two to three years of age and many of these deaths are due to male bears.  However, for roughly 55 days from late May into July, males and females form serially monogamous unions staying together for days or a couple of weeks.  The male attends the female during this time to maximize his fertilization of her eggs.  However, different cubs within a single litter are frequently fathered by different males.  Once fertilized, an egg will divide a few times before entering a state of suspended animation.  It then remains in this state until autumn when it will implant on the uterine wall and begin to grow again.

Most cubs stay with their mother until 3 years of age and the average interval between litters is four years.  During these 3 years, the young bears undergo an intensive education on how to utilize the resources in their environment and how to survive its threats.  Much time is spent in play as the young bears learn social skills that will help it to interact with other bears with minimal conflict.  The bears utilize a wide variety of food resources through the year, each with its own specific location and optimum timing.  This knowledge is critical for the cubs to learn in order to thrive on their own.  Upon leaving their mother, Kodiak bears become sexually mature at five years of age and will produce cubs of their own throughout their lives.  Mortality rate remains high for young bears in the first years after leaving their mothers as they face the challenges and risks of the environment alone.

In September and October, the bears return to the lowlands to feed on salmon along lake shores, tributary streams and tidal flats.  Alder patches at higher elevation continues to be used during this time for areas to hide and rest.  When salmon are plentiful, the bears may feed on only the most nutritious and fat rich portions of the fish.  These parts include the brains, eggs, and skin.  It is common to see the bears peeling the skin off of a still dying salmon while leaving much of the meat behind.

Kodiak brown bear eating salmon

When the salmon are less plentiful, the bears will consume more of fish.  During the late stages of the salmon’s life cycle, after its eggs have been deposited on the river bed, the spawned out fish become lethargic and slow swimming.  This allows young cubs to try their hunting skills to catch these slow and easy targets.  While the young cubs do not necessarily eat these dying fish, the act of catching the salmon serves as good training for the future.

For most of the year, Kodiak bears are highly solitary.  Males forage alone and females maintain the company only of their dependent cubs.  During these times, the bears are quite intolerant of each other’s close presence.  However, when food is especially plentiful, the bears become much more tolerant and numerous bears can be seen fishing in relatively small areas of water.  When in these large groups, the bears utilize a complex body language and social structure which allows them to make use of the same high value feeding opportunity while expressing their feelings and minimizing overt conflict.

Kodiak brown bears wrestling

The bears’ tolerance of each other closely mirrors their tolerance of people.  Much of the time, Kodiak bears will flee at any sense of a nearby human.  Their incredibly keen senses of smell and hearing usually alert the bear well in advance of a bear-human encounter and the bear simply leaves the area.  The same flight behaviour applies when approached by a boat or low flying plane.

This creates a significant ethical issue for any human that seeks proximity with these bears for photography or simple viewing.  If the bears detect the human presence and flee, they are being displaced from critical habitat and in so doing are compromised in their all important mission to put on adequate weight for the upcoming hibernation and for bearing young.  Governmental agencies must consider this disruption when allowing human use of bear habitat.  Further, the individual who uses the bear habitat must be responsible for minimizing any stress and displacement upon the bears.  In our photography of Kodiak bears, great care is made to remain undetected and leave the bears in their natural, undisturbed state whenever possible.

Towards the end of October and into November the bears begin to return to their dens to prepare for another winter.  In the days and weeks prior to denning, the bears enter a phase of hyperphagia in which they eat tremendous amounts of food.  The bears’ calorie demands at least double and perhaps triple as they build essential fat for hibernation.  The fertilized eggs that entered suspended animation in the spring or summer will not implant if insufficient fat stores are built.  Moreover, there is evidence the selective abortion may occur in which one or two fertilized eggs are sacrificed in order to increase the probability that the remaining embryos will survive.  Even if the egg implants, if there is borderline nutritional status, both the mother and the newborn cub may emerge from the hibernation underweight, decreasing their chances of survival.  So, after eating as much as possible, pregnant females are the first to enter the dens and males are the last.  This brings another year in the lives of these great bears full circle with hopes for the next generation sleeping beneath the snow, dependent on the energy stored through a season of feeding in this rich and unspoiled wilderness on Kodiak Island.

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info@markenarson.com (Mark Enarson Images) Kodiak Island Kodiak brown bear cub foraging predation seasons http://www.markenarson.com/blog/2013/3/seasons-of-the-great-bear Sun, 17 Mar 2013 04:53:39 GMT
Transients - The Whale Killers http://www.markenarson.com/blog/2013/3/transients---the-whale-killers At up to 30 feet in length and weighing up to 10 tonnes, the intelligent and pack-hunting orca is unrivalled as the ocean’s top predator.  Roughly 100 000 years ago, orcas divided into separate populations which have been called the residents and transients.  These groups have developed differences in social structure, anatomy, diet, and hunting strategy.   Resident orcas live in larger, life long groups of a mother and her generations of offspring.  These highly vocal orcas seem to feed entirely on fish.  Transient orcas on the other hand have a more fluid social structure and silently hunt primarily mammalian prey in smaller groups, vocalizing primarily after or between hunts.  Observations of the transients hunting and killing large whales provided the source for the common name “killer whale”.

Although these groups may live in similar areas, the residents and transients never mix.  Their interactions range from avoidance to outright aggression in rare cases.  Many of the differences between the groups seem to ultimately relate to their effects on predatory strategies.  In groups of resident orcas, individual orcas never leave the group into which they are born and stay with their mother and siblings for life.  These groups can contain a mother and up to five of her offspring with multiple generations of reproductively active females (called a “matrilineal group).  As a result, up to 4 generations of related orcas live together.  A typical resident pod contains one or more related matrilineal groups of up to 30 or more orcas.  These large groups likely benefit the resident orcas who must hunt for widely spread schools of fish.  Having more individuals in the group to find the fish must increase their ability to hunt.

Killer whales (orca) after the kill

In transient orca societies, young orcas of both sexes may leave their mother as a juvenile or adult to travel alone or to join with other transient orcas.  Further, this dispersal from the group where they were born is not always permanent.  First born males are likely to stay with their mothers.  Others might be forced to leave as increased group size makes it more difficult to mount sneak attacks on marine mammals.  Females seem to disperse around sexual maturity.  While adult males may travel alone as roving males, females do not.  Females associate with multiple transient pods for short times with each of these pods containing an adult male.  Roving males move from pod to pod or travel alone with no enduring relationships.  These roving males never travel together or with other lone individuals.  

Stable transient pods typically have three to five individuals.  This number likely represents an ideal number for stealth hunting.  Certain types of prey seem to require larger groups such as large and dangerous prey like grey whales.  Individual pods tend to regularly associate with other pods that have similar hunting tactics and socialization to undertake these hunts.  When small pods group together for hunting, they also spend a considerable amount of time socializing.

In all orcas, gestation is 16 to 17 months long.  Babies are roughly 2.5 m in length at birth and weigh about 200 kg.  These calves nurse until at least one year of age and many continue to nurse beyond this time for social and bonding reasons.  They begin taking solid food around six months of age.  Mortality for calves is approximately 40% in the first year of life.  Young orcas spend much of their time with their mothers.  They participate in hunts and are taught the tactics of their group.  Orcas become sexually mature between 11 and 15 years of age in females and between 12 and 14 years in males.  Males ultimately reach 8-9 m in length and weighing 9-10 tonnes while females are somewhat smaller at 7-8 m in length and weighing 7-8 tonnes.  Females continue to give birth every 3 years or more until they are about 40 years of age,  Orcas are unusual among mammals in that females live beyond their reproductive years like humans.  The average life span of an orca female is 50 years while the average is only 30 years for males.

Killer whale (orca) spyhopping

Resident orcas are highly vocal with each group demonstrating a well developed dialect of calls.  These calls may be clicks which are used for echolocation or harsh, strident burst-pulse calls and whistles which seem to provide a means for the orcas to communicate.  These calls are mostly used when the group is out of visual contact.  Each resident group has a characteristic series of calls which are stable over time and are taught to their young.  Transients by contrast are relatively quiet.  They have fewer calls which tend to be broadly shared between groups.  A resident group will have between 7-17 distinct calls whereas transient groups have only 4-6 calls of which at least two are common to all transients.  The commonality of transient calls likely relates to their fluid social structure whereas the smaller number of calls is likely a function of their hunting strategy.  Unlike fish, marine mammals are highly sensitive to the high frequencies of orca calls.  Thus, a transient’s prey is easily able to hear these calls and would flee the hunting orcas.

As a result, transient orcas are quiet and stealthy while hunting.  Like residents, they use echolocation clicks but they use these clicks in short, irregular bursts that can be camouflaged by the snapping and popping sounds made by marine invertebrates in near shore waters.  This allows the transients to get a brief snap snot of their prey’s location without revealing their own position.  In addition to echolocation, the transients passively listen to the sounds of splashing and swimming that alert them to the location and movement of the prey.  This all contributes to an ambush strategy of hunting.

Resident killer whale (orca) in Johnstone Strait

A stealth hunting lifestyle requires that the transients are always on the move.  If they stayed in any one place for too long, their prey would become alert to their presence.  The transients hunt in two general locations.  They spend part of their time hunting near shore waters, swimming close together while hugging the shore line in search of seals and sea lions.  In these locations they often demonstrate considerable knowledge of good hunting sites, heading directly to local seal and sea lion haul out spots.  Open water hunting is used to hunt for porpoises and dolphins or less frequently for large whales.

Attacks on small seals can be over quickly.  These small animals are a relatively easy and low risk prey for the transients and as a result, these attacks are usually successful.  The orcas either chase the seal and grasp it in their mouths or strike it with their tails in order to immobilize the victim.  Larger prey such as a male Steller or California sea lion are less common requiring more effort and risk.  The orcas will only attempt a predation on these large animals if the conditions are favourable.  They help to mitigate the risk by  attacking in larger groups.  If the animal is intercepted far from land, the orcas will surround the sea lion and then take turns charging the prey to ram it or strike it with their tails.  This type of attack may take an hour or two leading to the sea lion tiring so that the orcas can drown it.  With this type of prey, the attack is frequently not successful with the large sea lion escaping roughly 50% of the time.  Once the animal is killed, the resulting food is shared among the orcas including between members of different pods that join together for the kill.

Dolphins and porpoises represent a different challenge.  While not large or dangerous, these animals are extremely fast and agile.  Again, the orcas join together into larger groups in order to cut off routes of escape and capture the fleeing prey.  Pacific white-sided dolphins require another modification in technique due to the extraordinarily large groups in which they often travel.  In these chases, the transient orcas will seek to isolate a small group or individual from the larger group before they capture ad subdue the dolphin.  Because of their speed and agility, it is not uncommon for Dall’s porpoises and dolphins to escape.

Kller whale (orca) separating a grey whale calf from its mother

Overall, large whales are probably rare targets for transient orcas.  They represent an entirely different level of difficulty and danger to the attacking transients.  In these cases, several smaller pods group together to separate a calf from its mother, before the batter and drown the young whale.  This is most commonly seen over the Monterey Canyon in spring, but is likely also a regular occurrence in winter calving grounds.  Up to 20% of humpback whales bear rake marks from the teeth of transient orcas and these may represent the orcas testing the humpbacks in order to find a weak or vulnerable individual for a full on assault.

In watching an attack by transient orcas, it is clear that these are the apex predator of all the oceans.  In fact, a small group of transient orcas in northern California appear to have developed a specialization for hunting great white sharks.  Found in all of the world’s oceans where food is abundant, orcas are the pinnacle of predator development.  Through their size, speed, co-operation and intelligence, these magnificent animals have mastered their domain and reign supreme in the watery realm.

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info@markenarson.com (Mark Enarson Images) dolphin grey whale killer whale orca porpoise predation resident orca seal social transient orca http://www.markenarson.com/blog/2013/3/transients---the-whale-killers Sun, 17 Mar 2013 04:43:14 GMT