292 ANIMAL INTELLIGENCE. 



the mould with his webbed feet. The burrow when 

 finished has several twists and turns in it, and is about 

 ten feet deep. If a rabbit burrow is available, the puffin 

 saves himself the trouble of digging by taking possession 

 of the one already made. The kingfisher and land-martin 

 also make their nests in burrows. 



Certain auks lay their single egg on the bare rock 

 while the stone curlew and goatsucker deposit theirs on 

 the bare soil, returning, however, year after year to the 

 same spot. Ostriches scrape holes in the sand to serve as 

 extemporised nests for their eggs promiscuously dropped, 

 which are then buried by a light coating of sand, and in- 

 cubated during the day by the sunbeams, and at night 

 by the male bird. Sometimes a number of female ostriches 

 deposit their eggs in a common nest, and then take the 

 duty of incubation by turns. Similarly, gulls, sandpipers, 

 plovers, &c., place their eggs in shallow pits hollowed out 

 of the soil. The kingfisher makes a bed of undigested 

 fish-bones ejected as pellets from her stomach, and ' some 

 of the swifts secrete from their salivary glands a fluid 

 which rapidly hardens as it dries on exposure to the air 

 into a substance resembling isinglass, and thus furnish the 

 " edible birds' nests " that are the delight of .the Chinese 

 epicm-es.' ^ 



The house-martin builds its nest of clay, which it sticks 

 upon the face of a wall, and renders more tenacious by 

 working into it Kttle bits of straw, splinters of wood, &c. 

 According to Mr. Grilbert White : — 



That this work may not, while it is soft and green, pull 

 itself down by its own weight, the provident architect has 

 prudence and forbearance enough not to advance her work too 

 fast ; but by building only in the morning, and by dedicating 

 the rest of the day to food and amusement, gives it sufficient 

 time to dry and harden. About half an inch seems a sufficient 

 layer for a day. Thus careful workmen, when they build mud 

 walls (informed at first perhaps by these little birds), raise but 

 a moderate layer at a time, and then desist, lest the work should 

 become top-heavy, and ruined by its own weight. By this 

 method, in about ten or twelve days is formed a hemispheric 

 nest, with a small aperture towards the top, strong, compact, 

 ^ Newton, Encycl, Brit., art. ' Birds.' 



