Effects of Carrying Radio Transmitters on Energy Expenditure of Pacific Black Brant

We compared daily energy expenditure and body mass changes of captive yearling black brant (Branta bernicla nigricans) with and without backpack-mounted radio transmitters in a repeated measures design. Daily energy expenditure was estimated by continuously monitoring O2consumption and CO2production for 24 hours. Carrying transmitters had no effect on daily energy expenditure (P > 0.10) or mass loss (P > 0.3). We detected no temporal variation in daily energy expenditure after attachment of transmitters, an indication that any acclimation occurred within the first 24 hours. Because experimental birds were confined to a small (45 × 60 × 74 cm) chamber during metabolism measurements, our results do not address the influence of transmitters on the cost of locomotion.