ИСТИНА

We measured resting metabolic rate (RMR) of Pied Flycatcher fledglings in the Moscow region in 2000-2005 years (953 chicks from 362 broods). Ambient temperature (Ta) was calculated as daily average temperature during a week before RMR measurement. We tried to estimate the effects of Ta on the fledgling’s night time RMR. This relationship was positive overall, but several factors influenced it including the age of the male parent, brood size and the chick’s sex. The relation between RMR and Ta was most pronounced in offspring of young (1 year old) males from small broods (<6 fledglings). The age of the female had no effect on this relationship. On average, RMR of offspring of old males (>=2 years old) tended to be higher than that of young ones, and the RMR of chicks in small broods was higher than that in large broods. The results suggest that chicks of low quality parents need additional favourable conditions to be able to switch to a costly energetic regime.