78 “TERRA NOVA” EXPEDITION, 
7.—MORTALITY. 
The mortality among Adeélies is very high during the breeding season, both among 
the young and the old, whilst an enormous number of eggs are wasted. 
Waste of life is due to the following causes :— 
The eggys. 
Skuas. 
Cocks fighting among the nests. 
Flood from thaw-water. 
Death of parents. 
Snow-drifts. 
Land-slides. 
The young chicks. 
Skuas. 
Land-slides. 
Interference with by cocks. 
Getting lost. 
Death of parents. 
The adults. 
Sea-leopards. 
Land-slides. 
Snow-drifts. 
In the above lists I have left out the wanton depredations committed by some of 
the expeditions which visit the Antarctic, owing chiefly to the hcence given to ignorant 
seamen, but such visits, being made at rare intervals, can have little effect on the 
population. 
Two of the causes in my list which are not dealt with elsewhere in my text are 
land-slides and snow-drifts. 
At Cape Adare, the screes at the foot of the cliff are perhaps the most thickly 
populated part of the rookery. As the thaw proceeds, boulders of different sizes are 
continually rolling down the cliff, some of them falling many hundreds of feet before 
they 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 land-slides are caused, which bury many hundreds of 
nests beneath them. Indeed, these great screes on which the nests are built have been 
formed by these land-slides taking place from year to year, and no doubt form the 
graves of thousands upon thousands of former generations. 
One such slide took place whilst we were at the rookery, doing terrible damage, 
