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 International the benefit to the Australian economy in terms of trade would be substantial'. Flow-on effects could include a boost to domestic markets for birds and a rejuvenated interest in breeding birds in captivity which could assist the recovery of rare species in the wild." Indeed, G. R. Wilson mentions "some international competitors such as Birds International" as a source of "considerable competition when they target markets with low animal-health standards" in his entry on trade in native birds in "The New Rural Industries" handbook of the Australian Rural Industries Research and Development Corporation. The company carries out activities other than