The next winter Jaeger found a poor-will, perhaps the same bird, hibernating in the same niche. Over a period of eighty days, from November 26, 1947, to February 14, 1948, he visited it periodically, examined it, and took its temperature. The body temperature was low, 64°-68° F., compared with more than 100° F. of an active bird; with a medical stethoscope he could detect no heartbeat, and a cold metal mirror held directly in front of its nostrils collected no moisture from its breathing. The body processes were evidently very low. The bird was banded for identification, and in the third winter the same bird wearing the same band was found to have returned to hibernate again in the same rock niche. But on subsequent visits it was missing--perhaps having lived out its allotted span, perhaps the prey of some predator. SNAKESKINS IN BIRDS' NESTS [Illustration] There are occasionally discovered behavior patterns of birds that are so unusual as to make one stop and wonder. They are unusual for birds generally, but in a species here and there they are the regular thing. Such is the placing of a shed snakeskin in their nests by some birds. A bird like the English sparrow, or the road runner, which uses a variety of material coarse or fine, would be expected to use shed snakeskins occasionally, as it came across them. But there are a number of species that seem to use snakeskins regularly in their nests. It would seem that the birds deliberately sought out the skins for this purpose, as though they were as much a part of the nest as the mud in the bottom of a robin's nest or the fresh green grass heads ornamenting the entrance to some weaverbirds' nests. SOME HABITS BAFFLING I have long since given up thinking that every aspect of a bird's life must serve a useful purpose. Indeed I have already pointed out some definite maladaptations. But usually every type of behavior has a logical origin. By considering its occurrence in various species and against the background of the bird's everyday life some correlations usually can be found. The list of birds habitually using snakeskins in their nests is short, as follows: 1. Great-crested flycatcher--belonging to the New World flycatchers, breeding in Eastern North America and nesting in holes. 2. Arizona crested flycatcher--a relative of the great-crested variety, with similar habits. 3. Blue grosbeak--an American member of the sparrow family, making an open nest in bushes. 4. Black-crested titmouse--a member of the chickadee family, living in Western North America and nesting in holes. 5. Bank mynah--a starling, living in southern Asia and nesting in holes in banks. 6. Rifle bird--an Australian bird of paradise, making a cup-shaped nest in trees. 7. Madagascar bulbul--making a cup-shaped nest in trees.