Dietary plasticity in pikas as a strategy for atypical resource landscapes

Varner, Johanna; Dearing, M. Denise

doi:10.1644/13-mamm-a-099.1

Cited by 51 publications

(63 citation statements)

References 67 publications

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“…However, the extent of ecological differences in chimpanzee habitats, such as rainfall or food availability, yet a lack of difference in physiological response between these habitats suggests that behavioral flexibility is an important contribution to widening chimpanzee ecological tolerance, and perhaps even the chimpanzee niche. Such range expansion or ecological tolerance due to behavioral flexibility is a widely observed phenomenon found in many other taxa (e.g., Suarez et al, 1999;Yeh and Price, 2004;Sol et al, 2005;Duckworth and Badyaev, 2007;Liebl and Martin, 2014;Varner and Dearing, 2014;Varner et al, 2016).…”

Section: Discussionmentioning

confidence: 88%

Seasonal Variation in Physiology Challenges the Notion of Chimpanzees (Pan troglodytes verus) as a Forest-Adapted Species

et al. 2018

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Section: Discussionmentioning

confidence: 88%

Seasonal Variation in Physiology Challenges the Notion of Chimpanzees (Pan troglodytes verus) as a Forest-Adapted Species

et al. 2018

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“…The average forage availability at unoccupied sites was only 0.19 vegetation 'hits' less than occupied sites. Although individual pikas have unique diet-selection criteria [88], as a species they are generalist herbivores capable of consuming a variety of graminoids, forbs and bryophytes [61,62]. Our measure of forage availability, however, did not address either vegetation diversity or the ratio of forbs: graminoids, both of which have been closely linked with metrics of pika population density elsewhere in the species' range [86].…”

Section: Discussionmentioning

confidence: 99%

“…Species that can modulate behaviors to counter temperature extremes often are better able to exploit beneficial microenvironments. American pikas are capable of proximately adjusting to temperature variation through changes in body shape [33], food cache placement [62] and sheltering [34]. The degree to which behavioral flexibility, in combination with acclimatization and developmental plasticity [85], will facilitate the persistence of pikas and other animals in rapidly warming environments merits additional research.…”

Section: Discussionmentioning

confidence: 99%

“…Vegetation hits above 0.50 m were considered inaccessible to pikas and were not included in our assessment. Both vascular (grasses, forbs, shrubs and trees) and non-vascular plants were included, as pikas also have been observed foraging on lichens and bryophytes [60][61][62]. We defined forage availability as the sum of all vegetation hits encountered along the four, 25-m transects.…”

Section: Habitat Characteristics Plot Characteristicsmentioning

confidence: 99%

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Microrefuges and the occurrence of thermal specialists: implications for wildlife persistence amidst changing temperatures

Hall

Chalfoun

Beever

et al. 2016

Clim Chang Responses

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Background: Contemporary climate change is affecting nearly all biomes, causing shifts in animal distributions, phenology, and persistence. Favorable microclimates may buffer organisms against rapid changes in climate, thereby allowing time for populations to adapt. The degree to which microclimates facilitate the local persistence of climate-sensitive species, however, is largely an open question. We addressed the importance of microrefuges in mammalian thermal specialists, using the American pika (Ochotona princeps) as a model organism. Pikas are sensitive to ambient temperatures, and are active year-round in the alpine where conditions are highly variable. We tested four hypotheses about the relationship between microrefuges and pika occurrence: 1) Local-habitat Hypothesis (local-habitat conditions are paramount, regardless of microrefuge); 2) Surface-temperature Hypothesis (surrounding temperatures, unmoderated by microrefuge, best predict occurrence); 3) Interstitial-temperature Hypothesis (temperatures within microrefuges best predict occurrence), and 4) Microrefuge Hypothesis (the degree to which microrefuges moderate the surrounding temperature facilitates occurrence, regardless of other habitat characteristics). We examined pika occurrence at 146 sites across an elevational gradient. We quantified pika presence, physiographic habitat characteristics and forage availability at each site, and deployed paired temperature loggers at a subset of sites to measure surface and subterranean temperatures. Results: We found strong support for the Microrefuge Hypothesis. Pikas were more likely to occur at sites where the subsurface environment substantially moderated surface temperatures, especially during the warm season. Microrefugium was the strongest predictor of pika occurrence, independent of other critical habitat characteristics, such as forage availability. Conclusions: By modulating surface temperatures, microrefuges may strongly influence where temperature-limited animals persist in rapidly warming environments. As climate change continues to manifest, efforts to understand the changing dynamics of animal-habitat relationships will be enhanced by considering the quality of microrefuges.

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“…At each site, we placed loggers at the talus surface in vegetated areas near the bottom of the talus slope where we had observed pikas foraging [34]. All surface loggers were shielded from direct solar radiation by moss.…”

Section: Methodsmentioning

confidence: 99%

The Importance of Biologically Relevant Microclimates in Habitat Suitability Assessments

2014

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Predicting habitat suitability under climate change is vital to conserving biodiversity. However, current species distribution models rely on coarse scale climate data, whereas fine scale microclimate data may be necessary to assess habitat suitability and generate predictive models. Here, we evaluate disparities between temperature data at the coarse scale from weather stations versus fine-scale data measured in microhabitats required for a climate-sensitive mammal, the American pika (Ochotona princeps). We collected two years of temperature data in occupied talus habitats predicted to be suitable (high elevation) and unsuitable (low elevation) by the bioclimatic envelope approach. At low elevations, talus surface and interstitial microclimates drastically differed from ambient temperatures measured on-site and at a nearby weather station. Interstitial talus temperatures were frequently decoupled from high ambient temperatures, resulting in instantaneous disparities of over 30°C between these two measurements. Microhabitat temperatures were also highly heterogeneous, such that temperature measurements within the same patch of talus were not more correlated than measurements at distant patches. An experimental manipulation revealed that vegetation cover may cool the talus surface by up to 10°C during the summer, which may contribute to this spatial heterogeneity. Finally, low elevation microclimates were milder and less variable than typical alpine habitat, suggesting that, counter to species distribution model predictions, these seemingly unsuitable habitats may actually be better refugia for this species under climate change. These results highlight the importance of fine-scale microhabitat data in habitat assessments and underscore the notion that some critical refugia may be counterintuitive.

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Dietary plasticity in pikas as a strategy for atypical resource landscapes

Cited by 51 publications

References 67 publications

Seasonal Variation in Physiology Challenges the Notion of Chimpanzees (Pan troglodytes verus) as a Forest-Adapted Species

Seasonal Variation in Physiology Challenges the Notion of Chimpanzees (Pan troglodytes verus) as a Forest-Adapted Species

Microrefuges and the occurrence of thermal specialists: implications for wildlife persistence amidst changing temperatures

The Importance of Biologically Relevant Microclimates in Habitat Suitability Assessments

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