Black-legged Kittiwake (Rissa tridactyla) Science Article 3
We investigated the seasonal pattern of changes in body condition of breedingblack-legged kittiwakes Rissa tridactyla in Svalbard (79 deg N) to evaluate whetherchanges in body condition were a consequence of the energetic demands of breeding(the reproductive stress hypothesis) or of voluntary anorexia to attain lower flightcosts during chick rearing (the programmed anorexia hypothesis). Adult bodycondition was recorded from early egg laying to fledging and was examined inrelation to date (relative to hatching), sex, parental time-budget, brood size andreproductive success. To distinguish between the two hypotheses we evaluate whetherthe reduction in body condition occurred during or ahead of the energetically mostdemanding part of the chick-rearing period. We combine our results on changes inbody condition and time-budget with published information on field metabolic rate(FMR) and chick energy requirements from studies in the same colony.Our calculations of adult energy requirements and energy intakes indicate that thefirst part of the chick-rearing period was energetically the most demanding period,because adult energy requirement per hour spent off the nest was highest in thisperiod, and adults were time constrained because of the need for 24-h brooding of thechicks.
Borge Moe, Ingveig Langseth, Marianne Fyhn, Geir Wing Gabrielsen and Claus Bech, JOURNAL OF AVIAN BIOLOGY 33: 225-234, 2002