Some of the items in my list require explanation. The screes at the foot of the cliff at Cape Adare are perhaps the most thickly populated part of the rookery. As the thaw proceeds, boulders of different sizes are continually falling down the cliff, some of them for many hundreds of feet before they finally plunge in among the nests on the screes, doing terrible damage, and often rolling some distance out into the rookery. At other times, owing to the bursting out of thaw water which has been dammed up at the top of the cliff, large landslides are caused which bury many hundreds of nests beneath them. In fact, these screes on which the nests are built have been formed by these landslides taking place from year to year, and no doubt form the graves of thousands upon thousands of former generations. One of these slides took place whilst we were at the rookery, doing terrible damage. A crowded colony of Adélies were nesting just below, and the avalanche passed right through and over them, causing the most sad havoc. We found hundreds of injured and dying, some of them in a pitiable condition. Several were completely disembowelled, others had the whole skin of their backs torn down and hanging behind them in a flap, exposing the bare flesh. Dozens had broken or dislocated legs and flippers.
The worst feature was that many were buried alive beneath the snow, or pinned down to the ground by masses of basalt. Twice I saw one flipper sticking out of the snow, moving dismally, and dug out in each case a badly injured bird which would have lingered perhaps for days, because loose snow does not always suffocate, owing to the amount of air contained in its interstices, and to the fact that diffusion takes place through it very readily. Several of us spent a long time in killing with ice-axes those that seemed too badly injured to recover.
It was remarkable to see the way in which all the nests which had escaped the avalanche, however narrowly, were still sat upon by their occupants, as if nothing had happened. Also I saw several badly injured birds sitting on their eggs, some of them soaked in blood, so that they looked like crimson parrots. The amount of bloodshed must have been great, as the snow was dyed with blood in all directions. As a cascade of water followed the avalanche, and continued for some hours, spreading out into little rivers among the nests, many were being deluged, and some of the penguins actually were sitting in the running water, in a vain attempt to keep warm their drowned chicks and spoiled eggs.
Sometimes, digging at hazard in the drifted snow, I came on birds that had been deeply buried, and though they were held down and kept motionless by the weight of the snow covering them, most of them were alive, and I have no doubt many dozens died a lingering death in this way. Such as had merely suffered broken flippers or legs, I spared, and the next day nearly all of these seemed to be doing well. One bird I found sitting on two eggs which were in the middle of a rivulet of water, so I lifted them out and put them on dry ground close by, but the parent would have nothing to do with them after this.
Fig. 64. ADÉLIES ON THE ICE-FOOT
A feature of the above scene, which one could not help noticing, was that however badly a penguin was injured it was never molested by the others, as is almost invariably the rule among other birds, including their near neighbours the skuas. I have seen a sick skua hunted continuously for over an hour by a mob of its own kind who would not allow it to settle on the ice for a moment's rest.
Another item of my list requiring explanation is “snow-drifts.”
During both spring and summer there are occasional snowstorms, and during these the birds sit tight on their nests, sometimes being covered up by drift. As a rule the bird on the nest keeps a space open by poking its head upwards through the snow, but sometimes it becomes completely buried. Air diffuses so rapidly through snow that death does not take place by suffocation, and the bird can live for weeks beneath a drift, sitting on its nest in the little chamber which it has thawed out by its own warmth. Generally after a few hours the snow abates and settles down sufficiently to expose the nest once more, but sometimes a breeze springs up which is not strong enough to blow the snow away, but simply hardens the surface of the drift into a crust which lasts for several weeks, and the birds are imprisoned in consequence. Then little black dots are seen about the surface of the drift, which are the heads of penguins thrust through their breathing holes.