Energetics of Black-legged Kittiwake Rissa tridactyla chicks.

We compiled the energy budgets of Black-legged Kittiwake Rissa tridactyla chicks in Kongsfjorden, Svalbard (79 deg N, 12 deg E), utilising (1) deuterium turnover rates to estimate food intake, (2) the doubly labelled water ((D2O-O18) method in conjunction with mass gain measurement and carcass analysis to determine energy requirements, and (3) laboratory assessed components of the nestling energy budget and production cost from mass gain measurements and carcass analysis. While (1) and (2) gave similar results we found that (3) underestimated the total energy expenditure by 13-21%. This is explained by (3) neglecting the activity costs. During the first 15-16 days after hatching Kittiwake chicks are regularly brooded by the parents, resulting in a saving of 19% of the metabolisable energy intake of the chick for this period. Beyond 16 days chicks live within the zone of thermal neutrality. The resting metabolic rate and the energy deposited as tissue (inclusive tissue synthesis) constituted 53% and 24% respectively, of the total energy budget over the entire nestling period. After 16 days, activity of the chicks increased considerably, making up 22% of the total metabolisable energy intake. The main daily proportion of energy delivered to each chick raised is 33% of the energy required by a pair of adult Kittiwakes. The parental investment in the inshore feeding Kittiwake is relatively high, in particular for pairs raising two chicks, when compared with offshore feeders.

Gabrielsen G.W., Klaassen M. & Mehlum F., ARDEA 80 (1): 29-40.