Birds make Nests to Help Young.

Star (Christchurch), Volume XLIV, Issue 184, 5 August 1931, Page 6

Birds make Nests to Help Young.

Nature Notes

By

James Drummond,

F.L.S.. F.Z.S.

English naturalist believes that the higher skill shown by small birds in making their homes, compared with the skill shown by large birds, arises not only from the builders’ defencelessness, but also from consideration for the veung. Nests of small birds are made in a way that surrounds and screens the nestlings. In addition, they concentrate the sitting bird’s incubating heat on the eggs.

A small bird loses Its body heat at a higher rate than a large bird loses its heat. Small birds’ great voracity, which makes them valuable friends to humans in respect to insect pests, and enemies in respect to crop's, helps to maintain their production of heat. To concentrate this on the eggs, the nest has a non-conducting lining and a hollow shape. In this way the development of the eggs is ensured, and the nestlings are protected until they develop a body heat sufficiently strong and pliable to enable them to lead a free life, during the warmth of the day at least. If these theories are sound, the native grey-warbler’s nest, almost completely closed in, with thick walls and the cosiest possible quilted lining, ranks as the best in New Zealand, which may be why the parasitical cuckoos favour it as a home for their young. The nest of a native bush-canary, or whitehead, illustrated here, lying on its side to show the cup. is a typical cosy, well-made nest of a small bird.