210 ANIMAL LIFE 



tion — from the merest depression in the shingle to the 

 elaborate felt-work of the chaffinch or the pendent 

 house of the ortolan. 



Sea-birds make no proper nest. They assemble in 

 vast numbers at a few isolated rocks, grassy cliff 

 slopes, or solitary sand-flats. These they revisit in 

 spring with great punctuality ; coming often from 

 great distances, and disappearing when their young 

 have grown capable. 



The terns and oyster-catchers lay their eggs 

 only just above high- water mark in little depressions 

 of the shingle or sand. The resemblance of the eggs 

 to pebbles is astonishingly close, both as to shape and 

 colouring (fig. 41). 



Gulls assemble on grassy slopes or marshes and lay 

 their eggs in depressions lined with weeds, grass, 

 or leaves. Guillemots lay right on the rock ledges. 

 Puffins utilise rabbit-burrows, and petrels the crannies 

 of rocks. 



Wading-birds that spend part of the year at the 

 shore, but nest inland, show little more skill than 

 their purely long-shore relatives in the construction 

 of nurseries. The curlew lays in depressions of the 

 moorland, the sandpipers on the shingle of rivers. 

 Herons make rough nests in trees. Swans collect 

 vast piles of debris without much artifice ; ducks and 

 geese are exceptional in lining their nurseries with down. 



Powerful and gregarious birds as a rule build 



• clumsy nests. Immunity from enemies seems to 



render line weaving unnecessary. Raptorial birds 



