Antarctica by Gabrielle Walker Read Free Book Online Page B

gasping on her behalf.
    Suddenly she opened her mouth wide, called loudly, with a deep-throated ‘coo-ee’, disappeared from view, and then hauled out in a dramatic whoosh of water and slush. Even though she came out on the opposite side of the hole from me I leapt back in alarm and Bob looked over and laughed. ‘Wahay! That was a thousand-pound rocket!’ The call was to her pup, who responded by hurrying over and clamping to her invisible nipple like a limpet.
    Bob told me that this urgent feeding process was the most important adaptation the Weddells had made to living down here, on the edge of survival. First the mothers store vast amounts of energy in their blubber—which is why they look so pumped up, as if their skin was ready to burst. Then they quickly dump an astonishing quantity of this into their pups. When they are nursing, even their blood is so full of fat it looks thick and creamy like a milk shake, and their milk itself is like warm wax. From just before birth to weaning, the mothers will lose nearly half their body weight in less than forty days. Bob pointed to a pregnant seal. ‘Right now she looks like a fuel bladder. After she’s pupped and weaned she’ll look like a long thin cigar.’ And the pups go the other way. They start at about seventy pounds, and within a month they will weigh five times as much.
    The effectiveness of this process is crucial for survival. Pups are more likely to live through to weaning if they are born to a larger mother. 10 And the heavier the pup when it is weaned, the more likely it is to survive to adulthood. 11 I like this. Survival not of the fittest, so much as the fattest.
    I also like the team’s other key finding. For clearing those two hurdles of first survival through to weaning, and then to maturity, it helps immensely to be born to an older mother. The svelte young things of maybe six, which have only just started to breed, turn out to be less effective at raising pups than the ones that have been around the block a fair few times. The researchers think this is because the older the mother is, the fatter she is likely to be and the more energy she can pump into her offspring. (The benefit disappears when the mothers get really old. In a reversal of middle-age spread, a twenty-two-year-old Weddell has such worn-down teeth from gnawing on years of sea ice that she is a less effective hunter, and hence tends to be less substantial than, say a fourteen-year-old.) 12
    The rest of the team was now struggling with a mother-pup pairing that didn’t want to play. They had managed to drag the pup over to the weighing sled as bait, but it was thrashing and wailing. The mother had humped her way over to the sled but refused to get on. She rolled over, buried her nose in the snow, arched her back and then tried to get out of the way of the student blocking her path. Everyone was still and silent. Would she settle? No, she rolled away again. ‘She’s not going to do it. We’ll leave them be.’
    They released the pup to rejoin its mother and, once again, they were now both as docile as ever, the drama apparently forgotten. Still it seemed like hard labour, and I could see that every data point was dearly won. I asked Bob why he was prepared to put in so much effort.
    â€˜The best ecological insights come from living in the field and grunting around from day to day,’ he said. ‘You can use satellite images all you like but you don’t really learn things until you are watching them every day saying “why are they doing that?”
    â€˜Most of the time on the ice they are just sleeping and nursing. But if you look at the same animals again and again you start to realise—that’s a good mom, that’s a bad one, that’s one’s mellow, that one’s psycho.
    â€˜Sometimes if you look down a hole with a parka over your head to block the light you can see them below the ice, perfectly at