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Marine Ecology Progress Series

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MEPS 651:183-198 (2020)  -  DOI:

Inter-colony foraging dynamics and breeding success relate to prey availability in a pursuit-diving seabird

Julia Gulka1,*, Edward Jenkins1, Laurie D. Maynard1, William A. Montevecchi2, Paul M. Regular3, Gail K. Davoren1

1University of Manitoba, Department of Biological Sciences, Winnipeg, MB R3T 2N2, Canada
2Memorial University of Newfoundland, Cognitive and Behavioural Ecology Programme, St. John’s, NL A1B 3X9, Canada
3Fisheries and Oceans Canada, St. John’s, NL A1A 5S7, Canada
*Corresponding author:

ABSTRACT: Spatial patterns of breeding seabirds are influenced by the distribution of resources in relation to the colony and the density of conspecifics from the same or adjacent colonies. We conducted an inter-colony comparison of foraging space use and behavior, diet, and reproductive success of common murres Uria aalge breeding at a large offshore and a small inshore colony on the northeastern coast of Newfoundland (Canada) during 2016-2018 under varying prey (capelin Mallotus villosus) biomass. Murres from the large offshore colony foraged over a greater area, with greater individual foraging distances, indicative of higher commuting costs compared to the smaller inshore colony. Although this pattern might reflect prey depletion near the offshore colony due to higher conspecific densities, it likely also reflects the greater distance to predictable, high-abundance prey aggregations. This is supported by high spatial overlap of foraging areas from both colonies near coastal, annually persistent capelin spawning sites. Adult diet was similar between colonies during incubation, but diverged during chick-rearing, with offshore murres consuming a higher proportion of alternative prey, while inshore murres consumed more capelin. These differences did not affect fledging success, although hatching success was lower in the larger colony, suggesting that divergent factors (e.g. predation, nest attendance) influence colony-specific population dynamics. Overall, our findings suggest that abundant local prey is key in shaping spatial patterns of breeding common murres in northeastern Newfoundland and results in apparently minimal intraspecific competition. As anthropogenic pressures on resource availability heighten, insight into factors influencing intraspecific foraging niche dynamics will be critical to inform management.

KEY WORDS: Common murre · Uria aalge · Inter-colony comparison · Spatial overlap · Foraging · Diet · Prey availability

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Cite this article as: Gulka J, Jenkins E, Maynard LD, Montevecchi WA, Regular PM, Davoren GK (2020) Inter-colony foraging dynamics and breeding success relate to prey availability in a pursuit-diving seabird. Mar Ecol Prog Ser 651:183-198.

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