An Experimental Study of Behavioral Responses to Nest Predation and Brood Parasitism in a Migratory Songbird

We expect birds to evolve life history traits that maximize lifetime reproductive success and that these traits will include behavioral responses to factors limiting reproductive success. These behavioral responses may be especially important for birds breeding in highly fragmented landscapes where brood parasitism by Brown-headed Cowbirds (Molothrus ater) and nest predation can greatly reduce reproductive success. I studied populations of Prothonotary Warblers (Protonotaria citrea) in a fragmented bottomland forest during 1993--2000 and conducted field experiments to determine if these birds respond to brood parasitism and nest predation in ways that reduce the negative effects of each. Brood parasitism by cowbirds reduces the reproductive success of Prothonotary Warblers by decreasing the hatching success of warbler eggs and the survival of warbler nestlings. The warblers accepted brood parasitism and did not choose nest sites inaccessible to cowbirds, defend nests during the egg laying period, desert parasitized nests, or avoid returning to sites where they had been parasitized. Whether or not Prothonotary Warblers returned to breeding sites and territories appears to be a function of their perceived breeding success in the previous year. Approximately 80% of double-brooded males and females returned in the following year. Unsuccessful males with a successful neighboring pair of Prothonotary Warblers returned at a higher rate than those with unsuccessful neighbors. Territory fidelity tended to be higher for males than females. Mate fidelity, age of the individual bird, and cowbird parasitism had little effect on site and territory fidelity. The between-year predictability of nesting success on territories was high and individuals appear to benefit by returning to territories where they produced two broods and by dispersing from territories where they produced no broods in the previous breeding season. The results of my research indicate that these birds may be able to avoid sites with chronically high rates of nest predation by not returning to areas where nest predation eliminates nesting success. Prothonotary Warblers, however, may be vulnerable to sites where rates of nest predation are low and levels of brood parasitism are high. In such a situation they will mainly produce cowbird young and have low reproductive success.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Biology

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2015

Author dc:creator

• Hoover, Jeffrey Paul

Contributors dc:contributor

• Robinson, Scott K.

• Biology, Ecology

Language dc:language

eng

Identifier

(MiAaPQ)AAI3017103

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/85340