Different Patterns of Parental Effort during Chick-Rearing by Female and Male Thick-Billed Murres (Uria Lomvia) at a Low-Arctic Colony

Jones, Ian L. and Rowe, Sherrylynn and Carr, Steven M. and Fraser, Gail S. (2002) Different Patterns of Parental Effort during Chick-Rearing by Female and Male Thick-Billed Murres (Uria Lomvia) at a Low-Arctic Colony. Auk, 119 (4). pp. 1064-1074. ISSN 1938-4254

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Abstract

Using temperature loggers and radio telemetry, foraging and brooding behaviors of female and male Thick-billed Murres (Uria lomvia) were measured during chick rearing at the Gannet Islands, Labrador, to quantify parental roles during this crucial stage of reproduction. We recorded 2,725 foraging dives by 10 females and 7 males during 1,416 bird-hours of monitoring. Our study birds made between 21 and 107 dives per day between 0327 and 2220 hours, with 54% of females’ dives and ,1% of males’ dives occurring in conditions of low illumination between sunset and sunrise. Males foragedmostly atmidday and, overall, made longer and presumably deeper dives (mean duration 116.2 6 37.6 s) than females(mean duration 84.1 6 46.0 s). The maximum dive duration recorded was 240 s. Final dives of foraging trips were inferred to include dives during which chick meals (;95% by number daubed shanny [Lumpenus maculatus]) were obtained. Those dives (mean duration 134.0 6 36.1 s) and dives in final diving bouts prior to return to the breeding site (mean duration 139.1 6 40.2 s) averaged longer than other dives, and longer in males than in females, but there was no difference between the sexes in their daily frequency. The modal travel time from the last dive in a feeding trip to arrival at the breeding site was 8 min (no difference between sexes), which represents a maximum travel distance at 65 km h21 of 8.7 km, suggesting that foraging occurred close to the colony. Females spent 9 h day21 (38% of day, mostly diurnal brooding) at breeding sites whereas males spent 16 h (67% of day, mostly nocturnal brooding). Taken together, these data indicated drastic differences in patterns of foraging and brooding behavior between male and female Thick-billed Murres, but suggest that individual and intercolony variation were also significant.

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