Habitat use, demography, and population viability of disturbance-dependent shrubland birds in the Missouri Ozarks

Populations of many bird species associated with early successional habitats are declining in numbers. To identify factors that may be limiting populations of these species, we studied habitat use and population demographic attributes in a suite of shrubland-nesting bird species with emphasis on yellow-breasted chat (Icteria virens), prairie warbler (Dendroica discolor), and indigo bunting (Passerina cyanea). We determined nest success, cause-specific nest-failure rates, seasonal fecundity, apparent adult survival, and breeding densities in 3 habitat types: 3- to 5-year old regenerating forest (n = 3 sites), glade (n = 3), and forest-pasture edge (n = 3). We evaluated hypotheses concerning the effects of year and habitat type on nest predation rates for 3 bird species and found support for both factors. We evaluated hypotheses concerning the effects of year and habitat type on breeding densities of 8 bird species and found support for both factors, though the support for these factors differed among species. Thus, variation among habitat types and years results in important effects on breeding bird species.; To better understand the population dynamics of two shrubland specialists (prairie warbler and yellow-breasted chat) and the impacts of forest management decisions on these species' long-term population viability, we used a modified Leslie-matrix population modeling approach in RAMAS/GIS. Habitat-specific breeding densities and demographic estimates were used to parameterize the models. We evaluated three model scenarios: one with current habitat availability and two with reduced habitat availability (one without regenerating forest patches and one without glade patches). This evaluation yielded information regarding interactions between breeding densities and productivity in early successional habitats.