The Relation between Latitude and Breeding Seasons in Birds

摘要: SUMMARY. 1  As one goes north from the temperate latitudes finds a general tendency for egg-laying seasons of birds all kinds to start later and at rate some 20 or 30 days per 10o latitude. 2  As south into northern tropical equatorial zones Accipitres, Coraciiformes, and, less extent, Passeres, their earlier earlier. 3  The Charadriiformes, Gralise, Herodiones, Anseres behave differently. In hemisphere they tend breed in than subtropical temperate. 4  There is tropics reach height main breeding somewhat before sun passes overhead. Two year are therefore quite common, but which only once select either northward (Accipitres, etc.) southward (Grallae, swing sun. 5  The proximate causes nature thought be temperature length day boreal zones, rain and/or intensity insolation near equator. The time arrival migration often an important factor. 6  Much occurs when getting shorter, indeed it proceeds rapidly while decreasing between 11 12 hours long. 7  There is, however, little shorter hours, almost none 10. 8  Under natural conditions exhibit no everywhere certain nor when, becoming longer particularly quickly.