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 Eden access the aviary through about of walkways, about 75% of which are elevated to let them see the birds in all areas of the aviary. Visitors can tour the facility on their own, or take a guided tour. The enclosure was built over indigenous forest and includes a natural gorge with a waterfall, and a 200-seat amphitheater. In 2014 the sanctuary was home to about 3500 birds representing more than 200 species. Birds of Eden Birds of Eden is the world's largest free flight aviary and bird sanctuary, located near Plettenberg Bay in the Western Cape, South Africa. The mesh