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
Rare Breeding Birds Panel Rare Breeding Birds Panel The Rare Breeding Birds Panel (RBBP) is an ornithological body which collects data on the breeding attempts and successes of the rarer species of birds in the United Kingdom. It was created in 1968 as a subcommittee of the RSPB, with representation from the Nature Conservancy Council (NCC) and "British Birds" magazine. In December 1972 it became an autonomous body, financed jointly by the BTO, RSPB, British Birds and, later, the NCC. Its role was given as: The aims of the Panel are to collect in one place all information on rare breeding birds so that