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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 sand-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 inr shallow pits hollowed out 
of the soil. The kingfisher makes a bed of undigested 
fish-bones ejected as pellets from her stomach, and 6 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 5 nests 55 that are the delight of the Chinese 
epicures. 5 1 
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 little bits of straw, splinters of wood, &c. 
According to Mr. Gilbert 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 b it 
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, 
1 Newton, Encycl Brit., art. ' ' Birds.’ 
