Pika (Ochotona princeps) losses from two isolated regions reflect temperature and water balance, but reflect habitat area in a mainland region

Abstract

Although biotic responses to contemporary climate change are spatially pervasive and often reflect synergies between climate and other ecological disturbances, the relative importance of climatic factors versus habitat extent for species persistence remains poorly understood. To address this shortcoming, we performed surveys for American pikas (Ochotona princeps) at > 910 locations in 3 geographic regions of western North America during 2014 and 2015, complementing earlier modern (1994-2013) and historical surveys. We sought to compare extirpation rates and the relative importance of climatic factors versus habitat area for pikas in a mainland-versus-islands framework. In each region, we found widespread evidence of distributional losslocal extirpations, upslope retractions, and encounter of only old sign. Locally comprehensive surveys suggest extirpation of O. princeps from 5 of 9 new sites from the hydrographic Great Basin and from 11 of 29 sites in northeastern California. Although American pikas were recorded as recently as 2011 in Zion National Park and in 2012 from Cedar Breaks National Monument in Utah, O. princeps now appears extirpated from all reported localities in both park units. Multiple logistic regressions for each region suggested that both temperature-related and water-balance-related variables estimated from DAYMET strongly explained pika persistence at sites in the Great Basin and in Utah but not in the Sierra-Cascade "mainland" portion of northeastern California. Conversely, talus-habitat area did not predict American pika persistence in the Great Basin or Utah but strongly predicted persistence in the Sierra-Cascade mainland. These results not only add new areas to our understanding of

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

“…Pikas are typically easy ( p usually > 0.90) to detect (e.g., [42,51,56]), and we assume that to be the case in GNP because: 1) individuals in GNP generally construct and defend obvious haypiles; and 2) individuals use vocalizations both for conspecific attraction and for territorial announcement/defense, so these calls are often given when surveyors enter a talus patch. Although detectability can vary between regions and locations (e.g., lower at some anomalously low-elevation sites, described in [57]), and observer variability can influence results, our field crew received training and conducted trials to measure these factors. In GNP, repeated surveys by each member of the 2009 field crew revealed that the identity of the individual was not a significant predictor (multiple linear regression, F-test, p >> 0.05) of the number and type of pika signs observed nor home ranges estimated, with the exception of one individual who overestimated vocalizations and HRs [78].…”

“…princeps (14–34 m: [64]), because inaccuracy and variability both increase as distance increases, using ocular estimation; and 2) administering multiple, intensive field-crew training sessions–after these, we found consistency among our field crew in making these HR estimates (difference between individuals using multiple linear regression, F-test p >> 0.05 [78]). Improved accuracy could potentially be achieved by use of laser rangefinders to estimate distance of talus-patch dimensions ( sensu [57]) or by using remotely sensed data, as in [58], although the latter can be extremely inaccurate, as quantified in this study, and suffers from not accounting for talus that is not pika-appropriate (generally, when talus rock diameters are all <0.2 m or >1.0 m; [65]).…”

“…To date, occupancy rates and apparent trends from re-surveys suggest that O . princeps’ status is more favorable in the Sierra Nevada and Rocky Mountain mainlands (e.g., [55,56]) than in more-isolated areas [42,57]. …”

“…princeps has collectively shown the heterogeneity and nuance with which climate can act on the distribution and occupancy patterns of mountain-dwelling animals. For example, re-surveys of locations of historic pika records in the interior Great Basin have demonstrated loss of pikas from >44% of those locations [42,57]. In contrast, at higher-elevation sites in the southern Rocky Mountains, Erb et al [56] reported that pikas persisted at 66 of 70 sites (5.7% loss).…”

Adaptive population divergence and directional gene flow across steep elevational gradients in a climate‐sensitive mammal

“…It has long been suspected that the thermal sensitivity of the American pika will ultimately threaten the species' viability in the face of climate change; such sensitivity has already been implicated in | 2521 population declines and local extirpations within the last decade (e.g., Beever, Perrine, et al, 2016;Jeffress, Rodhouse, Ray, Wolff, & Epps, 2013;Stewart et al, 2015Stewart et al, , 2017, including within NOCA itself (Johnston et al, in review). In fact, we recently provided physiological evidence of climate-induced stress in American pika populations at our sample sites (Waterhouse et al, 2017).…”