Evidence from a Landscape Population Model of the Importance of Early Successional Habitat to the American Redstart

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[edit] Author(s)

  • Hunt, P. D.

[edit] Journal

Conservation Biology 12.6 (1998): 1377-89.

[edit] Keywords

bird communities migratory birds complex landscapes nest predation forest trends quality fragmentation demography songbirds

[edit] Abstract

Several lines of evidence indicate declines in American Redstart (Setophaga ruticilla) populations in northeastern North America. I used data on historical changes in forest characteristics to test the hypothesis that these declines are a consequence of forest maturation and subsequent loss of the early successional habitats preferred by redstarts. Comparison of Breeding Bird Survey data on redstart abundance with those on habitat change in Vermont and New Hampshire revealed two major patterns. In three regions, redstart abundance was positively correlated with the amount of early successional habitat whereas in two others it was positively correlated with total forest area. A mathematical model incorporating historical patterns of habitat change generated population trajectories that were reasonable approximations of the Breeding Bird Survey data for five of sir regions when parameterized to reflect the higher suitability of early successional habitats. For this model to approximate observed trends redstarts had to occur at higher densities in early successional habitats and experience higher nest success and juvenile survival there than in mature for-est. In particular, unless nest success in early successional habitats was higher than published values for mature forest, simulated populations declined toward extinction. These results suggest that mature forests may frequently function as sink habitats for American Redstarts and that recent redstart population declines have resulted from losses of early successional habitat.

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