Foraging Flights of Breeding Thick-Billed Murres (Uria lomvia) as Revealed by Bird-Borne Direction Recorders

Abstract

A bird-borne data logger, which stores flight directions at regular intervals, was used to reveal the foraging patterns of Thick-billed Murres (Uria lomvia) breeding at Latrabjarg in northwestern Iceland. Tracked birds traveled 10 to 168 km one-way to foraging sites in a narrow sector to the northwest of the breeding colony. The pattern of foraging activity was rather constant. Outbound birds stopped briefly several times, possibly testing prey availability. The longest stops occurred at sites close by the turning point of the out­bound journey. During the inbound flight, stops were less frequent and shorter than on the outbound flight, suggesting that the sequence of stops was not the expression of a disturbance caused by the instruments