About Harpactes kasumba (Raffles, 1822)
The red-naped trogon, Harpactes kasumba, is a strongly sexually dimorphic species, with females generally being duller than males. Males have a black head and upper breast, a blue bill and eye ring, and a bright blue face. They have yellow-brown upperparts and upper tail with black outlines, a white breast line, bright red underparts, and black-and-white undertail. The species' defining characteristic, which gives it its name, is a band of bright red feathers across the back of the male's head. Females are plainer than males, with a grey-brown head and upper breast and yellow underparts. Both sexes reach up to 32 centimetres (12.5 inches) in length, and have an average lifespan of approximately 7.3 years. Their legs and feet are short and weak, so they cannot walk and are only able to shuffle occasionally along branches. For all trogons (family Trogonidae), leg muscle makes up only 3% of body weight, the lowest ratio recorded in any bird. The toe arrangement of trogons is unique among birds: it is heterodactylous, meaning the third and fourth toes point forward, while the first and second point backward. Because of this arrangement, red-naped trogons cannot turn around on a branch without help from their wings for movement. They have compact bodies, short but strong wings, and a long tail. Wing muscle makes up approximately 22% of their body weight. Despite having strong flight, red-naped trogons do not fly long distances, usually flying no more than a few hundred metres at a time. The red-naped trogon is a non-migratory sedentary species, staying in the same location year-round instead of migrating. It is restricted to the lowlands of Sundaic region (Sundaland), a biogeographical region in Southeast Asia that covers the Sunda shelf, the Asian mainland's Malay Peninsula, the large islands of Borneo, Java, and Sumatra, and their surrounding islands; the region's eastern boundary is the Wallace Line, which separates the Indomalaya and Australasia ecotones. The species' total distribution covers 989,000 km². The global population size has not been quantified. The species is described as rare in Thailand, fairly common in Peninsular Malaysia and Sumatra, rather scarce in Sarawak, and uncommon in Singapore, Indonesia, Sabah, and Brunei. The population is currently declining at a moderately rapid rate, due to habitat loss and degradation across the species' range. The number of mature individuals is unknown. The species does not experience extreme population fluctuations, but has a continuing decline in mature individuals. Its population is not severely fragmented, not all individuals belong to one subpopulation, continuing decline in subpopulations is unconfirmed, and subpopulations also do not experience extreme fluctuations. Red-naped trogons occur mainly in primary or lightly logged lowland evergreen forests. They are most abundant below 600 metres, but have occasionally been found up to 1,200 metres in montane dipterocarp forest in Borneo. They have also been recorded in peat-swamp forest, logged areas, thick bamboo groves, coconut plantations, and cocoa plantations.
