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
Birds of the Amazon Birds of the Amazon An immense number of bird species live in the Amazon rainforest and river basin (an area which is nominally home to one out of every ten known species of animal). Over 1,300 of these species are types of birds, which accounts for one-third of all bird species in the world. The diets of rainforest birds greatly differ between species, although, nuts, fruits and leaves are a common food for many birds in the Amazon. Birds migrate to the Amazon rainforest from the North or South. Amazon birds are threatened by deforestation since they primarily reside in