Time budgets of Common Murres vary in relation to inshore Capelin availability
Wilhelm SI, Walsh CJ & Storey AE (2008) Condor 110 (2):316-325
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.
Keywords: breeding biology, brooding, foraging effort, food availability, Mallotus villosus, Newfoundland and Labrador, Uria aalge
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