ON THE HOUR OF LAYING AND HATCHING OF BLRDS‘ EGGS.

摘要: Summary. 1 Observations on the hour of day when eggs are laid presented for about 40 species Central American birds; observations hatching 14 species. 2 In a single locality each has its own time laying. There also well marked family trends, to which, however, exceptions found. Tanagers, finches (with one decided exception), wood warblers, honeycreepers, wrens, and hummingbirds usually lay early, from before soon after sunrise. Turdus grayi lays considerably later. flycatchers consistently later than tanagers, finches, etc., often waiting until second half forenoon. Manacus aurantiacus two Crotophaga around midday; goatsucker Nyctidromus albicollis rather late in afternoon. 3 Birds which sunrise show less variation laying those day. 4 Among birds sets two, some deposit both at same hour, so that interval between layings is 24 hours (e.g. tanagers very small finches). Others egg morning first, 25 or 26 larger Arremonops Saltator). Tioris olivacm three, Troglodytes musculus whose set three four, their intervals approximately hours. 5 The hatching, given nest, more variable laying. 6 With genus Myiozetetes, hatch during (late ?) night forenoon, scarcely ever afternoon. Apparently there diurnal rhythm birdling's efforts break through escape shell. 7 With tanager Ramphocelus passerinii, predominantly not infrequently afternoon, rarely night. Here predominance forenoon may be caused by constancy length incubation period this retarded. 8 Among passerine birds, seems tendency afternoon far frequently would expected if distribution event were random day. But apparent noted.