Graduate Program

Biological Sciences

Degree Name

Master of Science (MS)

Semester of Degree Completion

2007

Thesis Director

Eric Bollinger

Thesis Committee Member

Scott Meiners

Thesis Committee Member

Tom Nelson

Abstract

In the Midwest, urban expansion and more intensive agricultural practices have reduced habitat available to most species of breeding birds. Linear wooded habitats including fencerows and riparian strips are a common habitat feature in many agricultural landscapes. Changes in agricultural practices and the subsequent reduction in grasslands and fencerows have lead to greater breeding densities in species that use the remaining fencerows as nest sites. This may lead to a lower nesting success due to factors such as higher predation risk. Specifically, it is not known how such linear habitats currently contribute to avian populations in central Illinois.

We monitored the nesting success rates and measured habitat features for shrubnesting birds in fencerow and riparian strip habitats at Prairie Ridge State Natural Area (PRSNA) in east-central Illinois and the surrounding agricultural landscape April-August 2006. We compared these data to similar data collected at PRSNA in 1997-1998. The most common nesting species for both time periods were American Robins (Turdus migratorius), Brown Thrashers (Toxostoma rufum), Mourning Doves (Zenaida macroura), Common Grackles (Quiscalus quiscula), and Northern Cardinals (Cardinalis cardinalis). Nest success rates varied between species, with Northern Cardinals having a significantly lower nest success rate (3.8%) in 2006 than in 1997-1998 (26.1%) (p

Fencerow and riparian strip nest success rates did not differ significantly (p>0.05) and a survival analysis showed that habitat type had no significant effect on species' nest survival (p>0.05). We found that although riparian strip habitats were significantly wider than fencerow habitats, nests were found at similar distances from the edges for both habitats. American Robin nest success was positively correlated with nest height. Common Grackle nests with higher visibility had lower rates of nest success. Mourning Dove nest survival increased as their nests were found in larger nest trees and their nest survival was decreased if they were found nearer to crop fields than non-crop fields.

Nest success outcomes and comparisons with other studies showed that the linear habitat available to central Illinois shrub nesters is not an ideal breeding habitat. Thus, linear habitats in central Illinois may be ecological traps. We found there was no significant difference between the fencerow and riparian strip habitat features found in areas of central Illinois in terms of impact on nest survival and nest success for shrubnesting birds. Therefore, land managers may treat them as similar habitats in evaluating the usefulness of those habitat features. Future research on fragmented linear habitats within the agricultural landscapes of the U.S. would be recommended, particularly in the area of linear forest edges as a comparison to fencerows and riparian strips.

Download

Included in

Biology Commons

Share

COinS