Document Detail

Prey density and the behavioral flexibility of a marine predator: the common murre (Uria aalge).
MedLine Citation:
PMID:  17824434     Owner:  NLM     Status:  MEDLINE    
Flexible time budgets allow individual animals to buffer the effects of variable food availability by allocating more time to foraging when food density decreases. This trait should be especially important for marine predators that forage on patchy and ephemeral food resources. We examined flexible time allocation by a long-lived marine predator, the Common Murre (Uria aalge), using data collected in a five-year study at three colonies in Alaska (USA) with contrasting environmental conditions. Annual hydroacoustic surveys revealed an order-of-magnitude variation in food density among the 15 colony-years of study. We used data on parental time budgets and local prey density to test predictions from two hypotheses: Hypothesis A, the colony attendance of seabirds varies nonlinearly with food density; and Hypothesis B, flexible time allocation of parent murres buffers chicks against variable food availability. Hypothesis A was supported; colony attendance by murres was positively correlated with food over a limited range of poor-to-moderate food densities, but independent of food over a broader range of higher densities. This is the first empirical evidence for a nonlinear response of a marine predator's time budget to changes in prey density. Predictions from Hypothesis B were largely supported: (1) chick-feeding rates were fairly constant over a wide range of densities and only dropped below 3.5 meals per day at the low end of prey density, and (2) there was a nonlinear relationship between chick-feeding rates and time spent at the colony, with chick-feeding rates only declining after time at the colony by the nonbrooding parent was reduced to a minimum. The ability of parents to adjust their foraging time by more than 2 h/d explains why they were able to maintain chick-feeding rates of more than 3.5 meals/d across a 10-fold range in local food density.
Ann M A Harding; John F Piatt; Joel A Schmutz; Michael T Shultz; Thomas I Van Pelt; Arthur B Kettle; Suzann G Speckman
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Ecology     Volume:  88     ISSN:  0012-9658     ISO Abbreviation:  Ecology     Publication Date:  2007 Aug 
Date Detail:
Created Date:  2007-09-10     Completed Date:  2007-10-10     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0043541     Medline TA:  Ecology     Country:  United States    
Other Details:
Languages:  eng     Pagination:  2024-33     Citation Subset:  IM    
Alaska Pacific University, Environmental Science Department, 4101 University Drive, Anchorage, Alaska 99508, USA.
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MeSH Terms
Algae / physiology*
Behavior, Animal*
Birds / physiology*
Competitive Behavior*
Feeding Behavior
Food Chain
Food Supply*
Marine Biology
Nonlinear Dynamics
Population Density
Population Dynamics
Predatory Behavior / physiology*
Time Factors

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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