Seed Dispersal by Fall Migrant Frugivorous Birds in an East-Central Illinois Woodland (Treefall Gap)

I investigated patterns of seedfall, avian frugivore pre- and post-foraging behavior, and seed germination and seedling success for several species of bird-dispersed plants in an east-central Illinois deciduous woodland. Using seed traps and a combination of natural and artificial fruit displays, I found that small seeds were dispersed by birds farther, on average, than large seeds and that small seeds had a much greater probability of being dispersed into treefall gaps than large seeds. I also found that based on the relative area of each habitat, seedfall was much higher than expected in treefall gaps, the best growing sites for seeds, than in undisturbed forest. By following the pre- and post-foraging movements of frugivores, I found that, after eating fruit, canopy frugivores left fruiting plants at a higher rate of speed than did understory frugivores. Canopy frugivores also had a higher probability of depositing seeds in treefall gaps than did understory frugivores. Finally, by mapping the seed germination and seedling survival patterns for seven species of bird-dispersed plants in a 150 x 150 m section of the woodland and following seedling success over the next four years, I was able to test three hypotheses concerning the advantages to adult plants of avian dispersal of seeds. Results for two species supported the Colonization Hypothesis; results from four species supported the Directed-dispersal Hypothesis; but no species supported the Escape Hypothesis. I was unable to explain the results of one species in the context of any of the hypotheses.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Ecology, Evolution, and Conservation Biology

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2015

Author dc:creator

• Hoppes, William Gary

• Biology, Ecology

Language dc:language

eng

Identifier

(UMI)AAI8600210

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/77624