Document: JUL-3-48-29

Gull-plant interactions: The pitter-patter of big feet.

ELLIS, J.C.*

Brown University, Providence, RI. 02912, USA ¹

Abstract:
Some of the most striking examples of community change appear to be driven by changes in the abundance of particular species with cascading effects on other members of an ecosystem. Extensive seabird colonies commonly occur on offshore islands and can profoundly influence the distribution and abundance of other species in coastal communities. Nesting seabirds influence terrestrial communities on islands both directly and indirectly via nutrient addition and disturbance. Gulls can have particularly large effects because of their high population densities, large body size, and extremely widespread distribution. Gull breeding populations have expanded substantially in northeastern North America, displacing other nesting seabirds from offshore islands. The goals of this study were to quantify the direct and indirect effects of nesting gulls on terrestrial communities on islands in New England. Results from gull exclusion experiments initiated in 1999 indicate that trampling and nutrient input had substantial impacts on plant biomass, cover, and diversity in gull colonies. Changes in plant community structure resulting from gull activities may have important implications for populations of herbivores and predators occurring in gull nesting areas.

Keywords: seabirds, terrestrial communities

This abstract is being presented at: 11:45 AM in session:
Oral Session #3: Avian Ecology.