American Ornithological Society
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© 2014 Cooper Ornithological Society
The Rusty Blackbird (Euphagus carolinus), an uncommon songbird often associated with northern coniferous wetlands, has experienced a precipitous population decline since at least the early 20th century. Here, we provide the first analysis of breeding-habitat occupancy at the wetland scale and make recommendations for streamlined monitoring. We modeled occupancy and detectability as a function of site (i.e. habitat-based) and sampling (i.e. visit-specific) variables collected at 546 wetlands in northern New England, USA. Wetland occupancy (mean 6 SE ¼ 0.07 6 0.02 in randomly selected wetlands, and 0.12 6 0.02 in all wetlands surveyed) was best explained by variables describing Rusty Blackbird foraging habitat (PUDDLES: a proxy for shallow water), nesting habitat (coniferous adjacent uplands), and evidence of beavers. In contrast to Rusty Blackbirds’ selection of pole-stage conifers at the nest-site scale, stand age did not affect occupancy at the wetland scale. It appears that most wetlands in northern coniferous forest landscapes, regardless of stand age, offer dense conifer patches nearby and provide suitable breeding habitat if quality foraging sites (e.g., areas of shallow water) also are available. Detectability (0.29 6 0.04) decreased with increasing wind speed, and decreased about fourfold over the course of the breeding season. Rusty Blackbirds responded to broadcast of conspecific vocalizations by flying toward the observer and perching more often than prior to broadcast, demonstrating that broadcasts can be a useful tool to enhance visual detectability. Given our results, observers can now focus site selection on wetlands and sampling conditions most likely to maximize detections of Rusty Blackbirds.
Powell, Luke L.; Hodgman, Thomas P.; Fiske, Ian J.; and Glanz, William E., "Habitat occupancy of Rusty Blackbirds (Euphagus carolinus) breeding in northern New England, USA" (2014). Biology and Ecology Faculty Scholarship. 13.
Luke L. Powell, Thomas P. Hodgman, Ian J. Fiske, William E. Glanz, Habitat occupancy of Rusty Blackbirds (Euphagus carolinus) breeding in northern New England, USA, The Condor, Volume 116, Issue 1, 1 February 2014, Pages 122–133, https://doi.org/10.1650/CONDOR-13-033-R1.1
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