Avian clutch size of increasing clutch size with increasing latitude. The proximate and ultimate causes for this pattern have been a subject of intense debate involving the ideas of group and individual selection. David Lack observed a direct relationship between latitude and avian clutch size. Birds near the equator laid approximately half as many eggs as those that resided in northern temperate habitats. He observed an increasing clutch-size from the equator towards the poles (something he referred to as the “latitude trend”) for many passerine (perching) birds, near-passerine (tree-dwelling) birds and in various other groups: Strigiformes, Falconiformes, Ciconiiformes, Laridae, Ralliformes, Galliformes, Podicipedifomes, and
Bunting (bird) Bunting (bird) Buntings are a group of Eurasian and African passerine birds of the family Emberizidae. They are seed-eating birds with stubby, conical bills, and are the Old World equivalents of the species known in North America as (American) sparrows. (However, these birds are not closely related to the Old World sparrows which are in the family Passeridae.) Some emberizids are still named "finches" rather than "buntings". Conversely, there are New World species retaining the name "bunting" which are now classed in the family Cardinalidae. Among those are the painted and indigo buntings. In taxonomic order (but see "Systematics" section