Biological Invasions

, 11:565

Effects of a habitat-altering invader on nesting sparrows: An ecological trap?

  • J. Cully Nordby
  • Andrew N. Cohen
  • Steven R. Beissinger
Original Paper

DOI: 10.1007/s10530-008-9271-9

Cite this article as:
Nordby, J.C., Cohen, A.N. & Beissinger, S.R. Biol Invasions (2009) 11: 565. doi:10.1007/s10530-008-9271-9


Many invading species impact native species through predation, parasitism or competition, while others affect natives indirectly by restructuring their habitat. How invasive plants affect native animals, and to what extent native animals respond to changes in their habitat and the novel selection pressures that follow, is not well known. We investigated the impacts of a habitat-altering invader, the Atlantic cordgrass Spartina alterniflora, on the nesting success of Alameda song sparrows (Melospiza melodia pusillula), a California Species of Special Concern, in tidal marshes in three sites in San Francisco Bay. Date of laying was the most influential factor in determining daily survival rate of nests, but whether the nest was placed in exotic Spartina was the most important ecological variable. Nests placed in exotic Spartina had a success rate that was 30% lower than those placed in native vegetation. Nests in exotic Spartina were significantly more likely to fail due to tidal flooding than were nests placed in native vegetation, because the densest stands of exotic Spartina occurred at significantly lower elevations relative to the tides. Our results suggest that exotic Spartina may be an ecological trap for song sparrows in San Francisco Bay, attracting birds to nest sites that are often destroyed by tidal flooding.


Alameda song sparrow Behavior Ecological trap Exotic species invasions Invasive cordgrass Melospiza melodia Nest success Spartina alterniflora Tidal salt marsh 

Copyright information

© Springer Science+Business Media B.V. 2008

Authors and Affiliations

  • J. Cully Nordby
    • 1
    • 2
  • Andrew N. Cohen
    • 3
  • Steven R. Beissinger
    • 1
  1. 1.Department of Environmental Science, Policy and ManagementUniversity of California, BerkeleyBerkeleyUSA
  2. 2.Department of Ecology and Evolutionary Biology, Institute of the EnvironmentUniversity of California, Los AngelesLos AngelesUSA
  3. 3.San Francisco Estuary InstituteOaklandUSA

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