Graduate Program

Biological Sciences

Degree Name

Master of Science (MS)

Semester of Degree Completion

Summer 2020

Thesis Director

Eric K. Bollinger

Thesis Committee Member

Britto P. Nathan

Thesis Committee Member

Gordon C. Tucker

Thesis Committee Member

Jill L. Deppe

Abstract

Grassland birds are a sensitive community and populations around the country have been declining. They are susceptible to low nest success due to loss of habitat and the small, fragmented patches that remain are often subjected to elevated levels of nest predation. The American goldfinch (Spinus tristis), which uses grasslands for feeding and nesting, is understudied given its abundance, due in part to its late-season nesting habits, and selection of taller woody vegetation as nesting substrate, which is atypical for many grassland nesting birds. American goldfinches were incorporated in this study which included nest height manipulation of goldfinch nests, to determine the effect of this variable on predation pressures for the east-central Illinois grassland bird community in Coles County, IL. Overall nest success for the grassland bird community was high (48.6%) and American goldfinch nest success was the highest of all species (58.18%).

Manipulation of nest height resulted in fewer raised nests being predated than both control and lowered nests, and significant changes in nest concealment occurred due to moving a nest either up or down the nesting substrate. The incorporation of the American goldfinch in grassland research may lend insight to whether nest height placement affects survival, rather than other nest site characteristics. Nest height manipulation is a novel way of potentially testing the importance of nest height for future survival projects.

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