Quantifying overlap and fitness consequences of migration strategy with seasonal habitat use and a conservation policy

Jonathan B Dinkins,Michael R Conover,Kurt T Smith,Christopher P Kirol,Jeffrey L Beck,Aaron C Pratt,Kirstie J Lawson,Frank C Blomquist

doi:10.1002/ecs2.1991

Jonathan B Dinkins, Michael R Conover + Show 6 more

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https://doi.org/10.1002/ecs2.1991

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Abstract

AbstractOur study aimed to delineate seasonal habitats and assess differential fitness related to migration strategy and seasonal habitat use of greater sage‐grouse (Centrocercus urophasianus, hereafter “sage‐grouse”). In addition, we evaluated benefits gained for sage‐grouse through the implementation of the Wyoming Core Area Strategy relative to protection of habitat and differences in nest, brood, and annual female survival. We compared the proportion of seasonal habitats that were within or outside Core Areas as delineated with 75% and 95% kernel density contours (KDE). The proportion of summer and winter habitats (95% KDE) that overlapped Core Areas was 0.69 of summer and 0.50 of winter habitat within a Core Area. We found no differences in nest or brood survival among migration strategies or within and outside Core Areas. However, females that did not migrate out of their respective winter habitat had lower risk of death, which highlighted year‐round benefits of winter habitat. Females had lower risk of death during winter with the lowest risk occurring during winter in Core Areas. Higher temperature and lower snow water equivalent during the breeding season and fall were detrimental to female survival, whereas neither had an effect on winter survival. Although Core Areas encompassed a large proportion of winter habitat, our results indicate that Core Areas (as delineated) were not the most direct way to protect winter habitat for sage‐grouse. During winter, sage‐grouse gathered within habitat conducive to winter survival, indicating that disturbances within these winter habitats may have broad consequences for sage‐grouse populations.

Highlights

Distinct seasonal ranges provide habitat functions for migratory animals throughout crucial life stages including birth and rearing (Kozakiewicz 1995)
Winters with aboveand below-average SWE had vastly overlapping kernel density contours (KDE); we only report on KDE for all winter locations combined (Fig. 1)
Proportion of sage-grouse habitat (95% KDE) overlap with 100% core regions was 0.95 and 0.91 of summer and winter, respectively (Table 3). This indicates that winter habitat was primarily nested within estimated breeding habitat; the Core Area Strategy disproportionately overlapped with summer habitats compared to winter habitats

Summary

Introduction

Distinct seasonal ranges provide habitat functions for migratory animals throughout crucial life stages including birth and rearing (Kozakiewicz 1995). Survival of adult female sage-grouse has the greatest potential to influence population growth in local and range-wide sensitivity and viability analyses (Johnson and Braun 1999, Taylor et al 2012). Research has identified avoidance responses by sage-grouse where winter habitat overlaps anthropogenic development (Doherty et al 2008, Carpenter et al 2010, Smith et al 2014, Holloran et al 2015). For these reasons, habitat used by sage-grouse during the winter should receive special attention as priority areas for conservation. Conservation measures for sage-grouse have been focused on breeding season habitats delineated by buffer areas around communal male display grounds (Connelly et al 2011, Doherty et al 2016)

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