Not‐so‐splendid isolation: modeling climate‐mediated range collapse of a montane mammalOchotonaprinceps across numerous ecoregions

Abstract

We modeled current and future distribution of suitable habitat for the talus-obligate montane mammal Ochotona princeps (American pika) across the western USA under increases in temperature associated with contemporary climate change, to: a) compare forecasts using only climate variables vs using those plus habitat considerations; b) identify possible patterns of range collapse (center vs margins, and large-vs small-sized patches); and c) compare conservation and management implications of changes at two taxonomic resolutions, and using binned-vs binaryprobability maps. We used MaxEnt to analyze relationships between occurrence records and climatic variables to develop a bioclimatic-envelope model, which we refi ned by masking with a deductive appropriate-habitat fi lter based on suitable land-cover types. We used this fi nal species-distribution model to predict distribution of suitable habitat under range-wide temperature increases from 1 to 7 ° C, in 1 ° C increments; we also compared these results to distribution under IPCC-forecasted climates for 2050 and 2080. Th ough all currently recognized lineages and traditionally defi ned subspecies were predicted to lose increasing amounts of habitat as temperatures rose, the most-dramatic range losses were predicted to occur among traditional subspecies. Nineteen of the 31 traditional US pika subspecies were predicted to lose Ͼ 98% of their suitable habitat under a 7 ° C increase in the mean temperature of the warmest quarter of the year, and lineages were predicted to lose 88-95% of suitable habitat. Under a 4 ° C increase, traditional subspecies averaged a predicted 73% (range ϭ 44-99%) reduction. Th e appropriate-habitat fi lter removed 40 -6% of the predicted climatically suitable pixels, in a stepped and monotonically decreasing fashion as predicted temperatures rose. Predicted range collapse proceeded until only populations in island-biogeographic ' mainlands ' remained, which were not in the geographic range center. We used this model system to illustrate possible distributional shifts under stepped changes in biologically relevant aspects of climate, importance of land cover and taxonomic level in species-distribution forecasts, and impact of using a single threshold vs multiple categories of persistence probability in predicted range maps; we encourage additional research to further investigate the generality of these patterns.

Predictors of Current and Longer-Term Patterns of Abundance of American Pikas (Ochotona princeps) across a Leading-Edge Protected Area

“…Additionally, aspects of vegetation cover have also been shown to correlate with pika distribution and indices of pika abundance (e.g., [43,44,45,46]). Suitable habitat in the southern portion of the species’ range has been repeatedly forecasted to be largely eliminated under future climate conditions [47,48,49]. However, research in locations with physically complex habitats that provide climatic microrefugia (e.g., low-elevation lava flows and moss-covered, heavily forested gorges), has shown that the species’ status and trend in such habitats are more robust than expected, considering the region’s macroclimate [50,51,52,53,54].…”

“…princeps at the species’ leading, northern (range) edge, where cold stress and persistent snowpack may play increased roles in limiting distribution, such that north-facing slopes and the highest elevations may have lower pika abundance. If a shifting climate is indeed driving extirpations of American pika populations in parts of the species’ range, the northern Rocky Mountains may be one of the species’ final refugia in the U.S. ([47,48], but see [54] for microrefugia-driven persistence in complex microhabitats). Additionally, very few studies have examined pika abundance across a large network of sites (i.e., [43,45,56,59,60] each of which involved <100 sites), and those with relatively large sample sizes span entire eco-regions and only examine occupancy (e.g., [61]), not abundance.…”

Novel genomic resources for a climate change sensitive mammal: characterization of the American pika transcriptome

“…Pikas have also emerged as an important study species for investigating extinction risk in the face of rapidly changing climates [5,7,12-15]. Unlike the majority of woodland montane fauna whose continuous habitat allows for cross-valley dispersal among mountain ranges, pikas reliance on high-elevation talus habitat precludes their ability for dispersal to cooler latitudes [9].…”

A diet rich in C3 plants reveals the sensitivity of an alpine mammal to climate change

“…We aimed to analyse faecal pellets using metabarcoding to identify the plants in the diet of the Royle's pika and examine the effects of talus characteristics, topography and plant richness; abundance; and seasonal dynamics (pre‐ and postmonsoon) on diet, across five sites in the western Himalaya, India. Food availability (plant species’ presence and abundance; Huntly, Smith, & Ivins, ; Dearing, , ; Wilkening et al., ; Bhattacharyya et al., , 2014a; Bhattacharyya & Ray, ), habitat topography (elevation, slope, aspect; Walker, Halfpenny, Walker, & Wessman, ; Deems, Birkeland, & Hansen, ; Wilkening et al., ; Rodhouse et al., ; Gurung et al., ) and predation risk (rock cover, crevice depth, distance to the nearest area of talus; Calkins, Beever, Boykin, Frey, & Andersen, ; Bhattacharyya et al., ,b; Castillo, Epps, Davis, & Cushman, ; Bhattacharyya et al., ) significantly impact the foraging ecology of the Royle's pika and potentially influence access to nutritive plants, and thereby affect individual fitness (Bhattacharyya, ). For talus‐dwelling Ochotona spp., talus size (area) and connectivity between talus are known to influence the habitat occupancy (Franken & Hik, ).…”