PARENT SESSION
Poster Session #43: Avian Ecology.
Thursday, August 9, 2001. Presentation from 3:30 PM to 5:00 PM. Exhibition Hall

Population growth indicates forest habitat quality for three species of neotropical migrant songbirds.

Knutson, Melinda¹, Powell, Larkin², Niemi, Gerald³, Hammer-Friberg, Mary⁴, Hines, Randy¹, Sveum, Colin¹, ^{1 2 3 4}

ABSTRACT- Land managers need information on bird habitat quality to guide management decisions. We estimated population growth () as an indicator of habitat quality for three species of neotropical migrant birds from upland forests and three types of floodplain forests in the Upper Mississippi River basin. For each species we tested the null hypothesis that the modeled population growth rate = 1 over a simulated 200–year time span. We estimated breeding season productivity with a dynamic, stochastic, individual-based model of songbird reproduction. We used nesting data from our study sites and estimates from the literature to parameterize the models. We found that productivity = 1.80 (±1.41 SD) fledglings per year for wood thrush (Hylocichla mustelina) females, 0.86 (±1.35) for prothonotary warblers (Protonotaria citrea), and 1.42 (±0.69) for American redstarts (Setophaga ruticilla). Population growth rate predictions were below replacement for prothonotary warblers ( = 0.86, ±0.04, 95% CI) and American redstarts ( = 0.90, ±0.02, 95% CI). Wood thrushes ( = 1.04, ±0.04, 95% CI) did not reject the null hypothesis of = 1.0. Wood thrushes and American redstarts had high productivity in upland habitats, while prothonotary warblers and American redstarts had the lowest productivity in early successional floodplain forests. Sensitivity analyses revealed differing effects of parasitism rates on the population growth rate of the three species. In general, higher nest parasitism rates resulted in trends of lower annual population growth.

KEY WORDS: population growth, neotropical migrant bird, habitat quality, nest productivity