Friday, 9 January 2015

Antarctica part 3 - Marine Mammals

Humpback Whales are recovering well from the devastation of the whaling years (from 1904 to 1965). The population that visits the Antarctic Peninsula for six months a year comes south to feed up on the abundant krill. During the southern winter, the whales swim north to warm waters off Brazil and South Africa to breed, where they eat little or nothing. This pair were so busy feeding that they took little notice of our zodiacs. The animal on the right has its head above water: the mouth is clearly visible (and many on the image to enlarge). I find watching Humpbacks even more of a thrill than watching penguins!

The Antarctic Minke Whale is much smaller than the Humpback, and usually much shier, but occasionally an inquisitive individual will cause a surprise by nosing up to a zodiac. They also migrate to warmer waters to breed. The Japanese still take over 400 Minkes from Antarctic waters annually for 'scientific' purposes. An interesting theory that I recently heard suggests that if Greenpeace and the IWC (International Whaling Commission) were to stop condemning Japan, then Japan would be likely to announce that their 'scientific' programme is complete and to back off of their own accord.  

We had various encounters with Orcas or Killer Whales during the two months I spent on board this season. My niece Sarah took this photo when a pod spent time close to the ship. A closer look between the fins of the adults reveals the head of a young calf! Different groups of Orcas have specialized diets: we believe that this is one of the resident Gerlache Strait pods that feeds on seals. Sometimes they ram icebergs with all their weight to try to dislodge sleeping seals. Another population specializes in hunting penguins; while a third targets Minke Whales, tiring them out by preventing them from surfacing to breathe. 

On the beaches of South Georgia, the main battles of the Elephant Seal beachmasters takes place in October. I took this photo in November, when the largest 12-year-olds were already back at sea after their exhausting month of defending harems, fighting and mating. Nevertheless, these young males were huge and fearsome beasts, and a few were still finding females to mate with. Here the beach was so crowded with seals that the King Penguins had to weave their way between them to reach their colony. 

These Elephant Seal pups were about ten weeks old when we spent an hour with them as we stood in the shallows, helping passengers onto zodiacs. They were constantly on the move, nuzzling each other, the zodiacs, and our boots. Their mothers wean them at three weeks, but they don't know that! So here they stay, each one patiently waiting for her return, until hunger finally forces them to swim out to sea and learn how to dive and catch fish and squid. An adult's average dive is for 20 minutes, to a depth of about 500 m. Males reach a weight of 3.7 metric tons. 

The Leopard Seal is a predator that all our passengers hope to see. Armed with a mouthful of razor-sharp teeth, they specialize in catching penguins in the water, but their diet includes squid, krill, fish and young Crabeater Seals too. The combination of long neck and large head makes even a distant Leopard easy to identify on an ice floe - if it's facing sideways!

Weddell Seals are best identified by mottled pelage, large rotund body and small head. While most Antarctic mammals and birds depend on krill for their food, Weddells feed mainly on fish, diving to great depths and often feeding under ice. At Deception Island in November we came across a Weddell Seal feeding an albino pup: pure white, with pink flippers. Unfortunately it is likely to have a short life at sea, as it certain to be conspicuous to predators. It may also have problems with weak eyesight.  

Finally, the region's most abundant mammal: the Crabeater Seal. We often see these seals hauled out on ice-floes, usually looking slender, elongated, and plain buff in colour. Misnamed by early sealers, Crabbies feed only on krill. They feed mostly at night, when they are vulnerable to attacks by Orcas and Leopard Seals. Making estimates of their population has proved difficult: totals from 10 to 75 million have been proposed. My usual thanks go to those who have provided photos to share. 

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