Individuals of many species of insects, birds, and mammals are darkly pigmented in humid climates and lightly coloured in dry ones. This may well be a camouflage adaptation—moist habitats are usually well vegetated and tend to lack pale colours. There are many exceptions to this so-called rule. The rule was proposed in 1833 by the German zoologist Constantin Wilhelm Lambert Gloger (1803–63). See also Allen's rule; Bergmann's rule.
Subjects: Zoology and Animal Sciences — Ecology and Conservation.