insular species; these include a number of species found in the Greater Sundas, one species in the Philippines as well as two species endemic to Cuba and Hispaniola respectively. Outside of South East Asia and the Caribbean, however, trogons are generally absent from islands, especially oceanic ones. Trogons are generally sedentary, with no species known to undertake long migrations. A small number of species are known to make smaller migratory movements, particularly montane species which move to lower altitudes during different seasons. This has been demonstrated using radio tracking in the resplendent quetzal in Costa Rica and evidence has been accumulated for a number of other species. The Narina trogon of Africa is thought to undertake some localised short-distance migrations over parts of its range, for example birds of Zimbabwe's plateau savannah depart after the breeding season. A complete picture of these movements is however lacking. Trogons are difficult to study as their thick tarsi (feet bones) make ringing studies difficult. Morphology and flight The trogons as a family are fairly uniform in appearance, having compact bodies and long tails (very long in the case of the quetzals), and short necks. Trogons range in size from the , scarlet-rumped trogon to the , resplendent quetzal (not including the male quetzal's tail streamers). Their legs and feet are weak and short, and trogons are essentially unable to walk beyond a very occasional shuffle along a branch. They are even incapable of turning around on a branch without using their wings. The ratio of leg muscle to body weight in trogons is only 3%, the lowest known ratio of any bird. The arrangement of toes on the feet of trogons is also unique among birds, although essentially resembling the zygodactyl's two forward two backward arrangement of parrots and other near-passerines, the actual toes are arranged with usually inner hallux being the outer hind toe, an arrangement that is referred to as heterodactylous. The strong bill is short and the gape wide, particularly in the fruit eating quetzals, with a slight hook at the end. There is also a notch at the end of the bill and many species have slight serrations in the mandibles. The skin is exceptionally tender, making preparation of study skins difficult for museum curators. The skeletons of trogons are surprisingly slender, particularly the skulls which are very thin. The plumage of many species is iridescent, although not in