The Effect of Area on Resource Competition among Migrant Birds at a Stopover Site

Few studies have focused on the habitat and resource requirements of migratory landbirds along migration routes. Habitat fragmentation may exacerbate the costs of migration by reducing food availability and/or increasing competition at crowded stopover sites. I predicted that smaller forest fragments would have higher densities of birds, and that birds would compete for food more intensely in smaller fragments. I examined seven forest fragments of varying size (0.69 ha - 5.69 ha) at Savannah National Wildlife refuge in three migration periods between Spring 2007 and Spring 2008. I set up netted exclosure pairs to examine the relationship among fragment size, bird density and resource abundance. I found that in Fall 2007 and Spring 2008, the density of migrant birds was higher in smaller fragments. In all three field seasons, the density of resident birds was higher in smaller fragments than in larger fragments. Birds did depress arthropod abundance in Spring 2007 and 2008, but there was no relationship with hammock size. Birds did not have a measureable effect on fruit resources in the fall. The higher density of both migrants and residents in smaller hammocks indicates that birds are responding to area during stopover. The difference between arthropod abundance in exclosure pairs indicates that birds use this food resource, and provides evidence for food competition.

Name thesis:degree_name

Master of Science in Biology (M.S.)

Level thesis:degree_level

Thesis (open access)

Discipline thesis:degree_discipline

Department of Biology

Year dc:date.available

2011

Author dc:creator

• Beall, Sara Marie

Contributors dc:contributor

• William Irby
• Lissa Leege

• ETD
• Stopover site
• Exclosures
• Neotropical
• Migrant
• Migration
• Competition

Repository record dc:identifier

https://digitalcommons.georgiasouthern.edu/etd/755

OAI identifier oai:identifier

oai:digitalcommons.georgiasouthern.edu:etd-1755