DAILY ENERGY-EXPENDITURE AND SHORT-TERM REPRODUCTIVE COSTS IN FREE-RANGING EURASIAN KESTRELS (FALCO-TINNUNCULUS)

1. The relationship between daily energy expenditure (DEE), measured u sing the doubly labelled water technique, and flight activity, rate of food delivery, daily mass change and body condition was studied in a population of the Eurasian Kestrel in Finland. Only female Kestrels we re recorded for flight activity.2. In female Kestrels, the time that t he bird was in sight was negatively associated with DEE, while ambient temperature, flying activity, daily mass change and body condition we re not related to DEE. When body mass and temperature were controlled for, there were still no associations between residual DEE and variabl es of flight activity, rate of food delivery, daily mass change, or bo dy condition. 3. In male Kestrels, there was a tendency for DEE to be associated with condition at the initial capture, but this relationshi p disappeared when body mass and ambient temperature were controlled f or in the analysis, Daily mass change and rate of delivery were not as sociated with DEE or residual DEE in male Kestrels, 4. Energy expendit ure in both male and female Kestrels increased faster than expected wi th body mass, suggesting that heavy individuals were more active than light ones, that expenditure increased faster than expected with body condition, or that the relative costs of flight increased with body ma ss.