ИСТИНА

The superiority of passerines in basal metabolic rate (BMR) over animals from other taxa was one of the main observed taxonomic differences in energetics of endotherms. With the exception of few recent tropical studies, this asymmetry was based mainly on temperate species and only on oscine representatives of Passeriformes. The high BMR in passerines could be one of the key physiological adaptations, which allowed them to occupy multiple ecological niches and reach high diversity. One could expect that more primitive Old World suboscine passerines (Eurylaimides), which are poor in species number, would have a lower BMR in comparison with oscines. Using allometric analysis of mean species’ BMRs in sedentary birds from southern Vietnam, we did not find significant differences between Old World suboscine and oscine passerines. However, the size range of all five measured suboscine species was too narrow to obtain reliable allometric coefficients. Therefore, we also analyzed large individual data set using body mass, season, reproductive status and other variables as predictors. According to analysis of individuals, subocines had significantly lower BMR than oscines. Taking into account the rich diversity of the New World suboscines, our result emphasized the need to compare the energetic difference between oscines and suboscines in two hemispheres.