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1 May 2008 Time Budgets of Common Murres Vary in Relation to Changes in Inshore Capelin Availability
Sabina I. Wilhelm, Carolyn J. Walsh, Anne E. Storey
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Changes in capelin (Mallotus villosus) biology since the 1990s have directly or indirectly induced variable breeding conditions for many seabirds in the Northwest Atlantic. Time budgets of the same individual Common Murres (Uria aalge) were examined in relation to annual variations in the arrival of inshore spawning capelin during three consecutive chick-rearing periods (1998–2000) on Great Island in the Witless Bay Ecological Reserve, Newfoundland, Canada. Despite high foraging effort (longer provisioning trips, lower co-attendance time, and faster colony departure after a brooding bout), chick-feeding rates were low during early chick rearing in 2000 due to a mismatch between early egg hatching and the later inshore arrival of spawning capelin. Time budgets of murres breeding on Great Island were examined in relation to those of murres in other nearby colonies and to long-term changes in capelin spawning behavior across decades (1982–1985 versus 1998–2000). Recent overall provisioning rates on Great Island were comparable to those of other nearby colonies during the same time period (with the exception of Funk Island) and to those reported during the 1980s. However, murres breeding in recent years in the reserve exhibited higher foraging effort, which is likely linked to recent changes in the availability of capelin as a result of later spawning, changes in capelin distribution, and their overall smaller size. Murres currently may be constrained to timing their egg laying such that hatching coincides with the arrival of inshore capelin rather than peak capelin abundance and, thus, are vulnerable to sudden changes in the ecosystem.

Sabina I. Wilhelm, Carolyn J. Walsh, and Anne E. Storey "Time Budgets of Common Murres Vary in Relation to Changes in Inshore Capelin Availability," The Condor 110(2), 316-324, (1 May 2008).
Received: 31 July 2007; Accepted: 1 May 2008; Published: 1 May 2008

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