Dr. Timothy Parker,
Post-doctoral Research
Assistant

Brooke Stansberry, M.Sc.
Candidate, Dept. Horticulture, Forestry & Recreation Resources

Kentucky Warbler

Research Theme: Biodiversity in Forest Fragments of the Great Plains

Research Title: Ecology of Neotropical migrant forest nesting songbirds at Fort Riley, Kansas

Principle Investigators:

Dr. C. Dustin Becker, PI

Dr. Philip S. Gipson, PI
Dr. Timothy H. Parker, Post-doc
Ms. Brooke M. Stansberry, M.Sc. candidate

We are studying several aspects of the ecology of Neotropical migrant birds nesting in forests on the eastern Great Plains.
 

Habitat Selection:

Neotropical migrant songbirds that nest in interior forests may be at risk from forest fragmentation. Males of many species are less likely to settle in smaller forest fragments, possibly because of the higher edge to area ratio. Also, males may be less likely to attract females in these habitats or may suffer reproductive failure due to higher predator or brood parasite density should they succeed in mating. Thus forest fragmentation has been indicted in the regional or range-wide declines of a number of forest-nesting species.

Although sensitivity to forest size and edge have been widely established in the eastern and mid-western portions of North America, the habits of forest nesting Neotropical migrants have been largely ignored in the naturally limited riparian forests of the Great Plains. Because the Great Plains were historically dominated by grassland, and in some areas still are, the forests in these areas provide an interesting contrast to the recent human-caused forest fragmentation further east. Forest birds may be attracted to settle in riparian forests on the plains either because they do not avoid forests of limited extent or because, despite sensitivity to patch size, some of the riparian forests are large enough to attract them. The former case might result from a longer evolutionary relationship with limited forests, or from the grassland matrix being less hostile than agricultural and suburban matrices. Whether or not these populations are sources or sinks is another issue. It could be that the high predation and/or brood parasitism characteristic of anthropogenic forest fragments are reduced in naturally limited forests in Great Plains grasslands.

We gathered field data at Fort Riley in Kansas, and examined an extensive set of published data. Published data suggest there is variation within bird species in landscape level habitat correlates. However, most species we studied showed strong affinities for the interiors of larger, less fragmented forest patches and/or stands with larger trees and greater canopy closure. Thus it seems that even in the naturally limited forests of the Great Plains, forest nesting birds are attracted to larger forest tracts. However, in our focal species, Kentucky warbler, forest vegetation variables did not predict either male pairing success (female settlement) or fledging success.
 

Behavioral Ecology:

We explored the factors that influence mating success in our focal species, Kentucky warbler. Approximately one quarter of the males at our site go unpaired. Pairing success was not influenced by territory vegetation, but was predicted by feather ornamentation. Males with more extensive black in their crown were in better body condition, and were more likely to attract a mate. In contrast, the yellow, melanin pigmented breast feathers, though brighter in males and so possibly sexually selected, did not correlate with condition or pairing success.
 

Manuscripts:

Parker, TH, BM Stansberry, CD Becker, and PS Gipson. submitted.Melanins versus carotenoids as pigments for sexually selected ornaments in a songbird.

Parker, TH, BM Stansberry, CD Becker, and PS Gipson. in prep. Landscape forest cover, but not territory scale vegetation, influences Kentucky warblers (Oporornis formosus) habitat use. 

Parker, TH, BM Stansberry, CD Becker, and PS Gipson. in prep. Comparisons of local and range-wide responses to forest cover explain settlement patterns of forest-nesting Neotropical migrant songbirds on the eastern Great Plain.