heavy metals and metalloids in egg contents and eggshells of passerine birds from arizona.concentrations of inorganic elements were determined in eggs of passerine birds including the endangered southwestern willow flycatcher (empidonax traillii extimus) from four regions in arizona. the main aim of the study was to determine the distribution of metals in egg contents and eggshells, with emphasis on the deposition of sr in eggshells. seventy eggs of 11 passerine species were collected at four nesting locations during 2000. aluminum, ba, cr, cu, mn, se, sr, and zn, were detected prima ...200312826417
management by assertion: beavers and songbirds at lake skinner (riverside county, california).management of ecological reserve lands should rely on the best available science to achieve the goal of biodiversity conservation. "adaptive resource management" is the current template to ensure that management decisions are reasoned and that decisions increase understanding of the system being managed. in systems with little human disturbance, certain management decisions are clear; steps to protect native species usually include the removal of invasive species. in highly modified systems, how ...200717318698
implications of climate change for bird conservation in the southwestern u.s. under three alternative futures.future expected changes in climate and human activity threaten many riparian habitats, particularly in the southwestern u.s. using maximum entropy (maxent3.3.3) modeling, we characterized habitat relationships and generated spatial predictions of habitat suitability for the lucy's warbler (oreothlypis luciae), the southwestern willow flycatcher (empidonax traillii extimus) and the western yellow-billed cuckoo (coccyzus americanus). our goal was to provide site- and species-specific information t ...201526700871
efficacy of stable isotope ratios in assigning endangered migrants to breeding and wintering sites.a primary constraint on effective conservation of migratory animals is our inability to track individuals through their annual cycle. one such animal is the endangered southwestern subspecies of the willow flycatcher, which is difficult to distinguish from conspecifics. identifying wintering regions used by the endangered subspecies would be an important step in formulating an effective conservation strategy. our objective was to use stable isotope ratios as a means of identifying wintering site ...200818488617
disparity in population structuring of southwestern willow flycatchers based on geographic distance, movement patterns, and genetic analyses.estimates of population connectivity often are based on demographic analysis of movements among subpopulations, but this approach may fail to detect rare migrants or overestimate the contribution of movements into populations when migrants fail to successfully reproduce. we compared movement data of endangered southwestern willow flycatchers among isolated populations in nevada and arizona from 1997 to 2008 to genetic analyses of samples collected between 2004 and 2008 to determine the degree to ...201425370444
songbird response to increased willow (salix spp.) growth in yellowstone's northern range.after nearly a century of height suppression, willows (salix spp.) in the northern range of yellowstone national park, u.s.a., are increasing in height growth as a possible consequence of wolf (canis lupus) restoration, climate change, or other factors. regardless of the drivers, the recent release of this rare but important habitat type could have significant implications for associated songbirds that are exhibiting declines in the region. our objective was to evaluate bird response to releasin ...201121939061
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