Oecologia

, Volume 155, Issue 4, pp 859–867

Movements of wintering surf scoters: predator responses to different prey landscapes

  • Molly Kirk
  • Daniel Esler
  • Samuel A. Iverson
  • W. Sean Boyd
Behavioral Ecology - Original Paper

DOI: 10.1007/s00442-007-0947-0

Cite this article as:
Kirk, M., Esler, D., Iverson, S.A. et al. Oecologia (2008) 155: 859. doi:10.1007/s00442-007-0947-0

Abstract

The distribution of predators is widely recognized to be intimately linked to the distribution of their prey. Foraging theory suggests that predators will modify their behaviors, including movements, to optimize net energy intake when faced with variation in prey attributes or abundance. While many studies have documented changes in movement patterns of animals in response to temporal changes in food, very few have contrasted movements of a single predator species naturally occurring in dramatically different prey landscapes. We documented variation in the winter movements, foraging range size, site fidelity, and distribution patterns of a molluscivorous sea duck, the surf scoter (Melanitta perspicillata), in two areas of coastal British Columbia with very different shellfish prey features. Baynes Sound has extensive tidal flats with abundant clams, which are high-quality and temporally stable prey for scoters. Malaspina Inlet is a rocky fjord-like inlet where scoters consume mussels that are superabundant and easily accessible in some patches but are heavily depleted over the course of winter. We used radio telemetry to track surf scoter movements in both areas and found that in the clam habitats of Baynes Sound, surf scoters exhibited limited movement, small winter ranges, strong foraging site fidelity, and very consistent distribution patterns. By contrast, in mussel habitats in the Malaspina Inlet, surf scoters displayed more movement, larger ranges, little fidelity to specific foraging sites, and more variable distribution patterns. We conclude that features associated with the different prey types, particularly the higher depletion rates of mussels, strongly influenced seasonal space use patterns. These findings are consistent with foraging theory and confirm that predator behavior, specifically movements, is environmentally mediated.

Keywords

Foraging theory Home range Melanitta perspicillata Prey depletion Site fidelity 

Copyright information

© Springer-Verlag 2008

Authors and Affiliations

  • Molly Kirk
    • 1
  • Daniel Esler
    • 2
  • Samuel A. Iverson
    • 2
    • 4
  • W. Sean Boyd
    • 3
  1. 1.Centre for Wildlife EcologySimon Fraser UniversityBurnabyCanada
  2. 2.Centre for Wildlife EcologySimon Fraser UniversityDeltaCanada
  3. 3.Canadian Wildlife ServiceDeltaCanada
  4. 4.United States Geological Survey, Western Ecological Research Center, San Francisco Bay Estuary Field StationVallejoUSA

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