ИСТИНА

Recent studies of life history traits and physiology have shown pronounced differences between birds of the tropics and temperate zones. During the last eight years, we collected the most extensive database of basal metabolic rate (BMR) measurements of Old World tropical birds. This database includes BMRs of more than 1100 free-living individuals of 117 species, from 15 orders captured in Southern Vietnam. In the first three years of this study we revealed some energetic features of tropical birds (Bushuev et al., 2017), which we seek to verify using our considerably enlarged data set. The present analysis based only on species with three or more measured individuals confirmed our previous main conclusions: 1) BMR of resident tropical birds is lower than that of temperate species; 2) the scaling exponent in the allometric relation between BMR and body mass is much lower in resident tropical birds than in temperate species; 3) in resident tropical species, passerine and non-passerine birds do not differ in BMR; 4) in passerines, long-distance migrants from temperate regions have higher BMR on their wintering grounds in tropics than tropical residents; 5) phylogenetic relatedness has no impact on mass-independent BMR. Contrary to our previous conclusion, suboscine passerines tended to have lower BMR than oscine passerines. One of the most interesting differences between our results and the results obtained in other geographic regions was the absence of passerine/non-passerine dichotomy in energetics.