ИСТИНА

One of the most distinctive characteristics of life histories in tropical birds is their slow pace of life. In general, tropical species live longer, have fewer chicks per breeding attempt and invest more resources in self-maintenance than temperate birds. The slow pace of life in tropical birds is accompanied by their low basal metabolic rate (BMR). According to some recent studies (Bech et al., 2016), the low BMR of tropical species may be related not to their slow pace of life or high ambient temperatures, but to the stability of tropical climate. Since the repeatability of energetic traits is higher in stable environments, such as laboratory conditions (Auer et al., 2016), we predict that BMR repeatability over long time intervals should be higher in tropical birds than in temperate ones. We estimated repeatability of BMR in 33 individuals from 19 species of recaptured free-living tropical birds from Southern Vietnam. The average interval between repeated BMR measurements was 510 days (min 250 days, max 1078 days). The adjusted repeatability of BMR after controlling for body mass was medium (R = 0.399; p = 0.005). Contrary to our predictions, the repeatability of mass-independent BMR was low and insignificant after including species affiliation in the model as a fixed effect. The result implies that, despite the stable environment in tropics, the individual variation in BMR of tropical birds is high due to the influence of factors such as season, reproductive status, etc.