Organizing the pantry: cache management improves quality of overwinter food stores in a montane mammal

Jakopak, Rhiannon P.; Hall, L. Embere; Chalfoun, Anna D.

doi:10.1093/jmammal/gyx124

Cited by 7 publications

(8 citation statements)

References 28 publications

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“…Taken together, our findings point towards increased plasticity as an alternative behavioural strategy that produces comparable overwinter stores, while simultaneously reducing exposure to potentially stressful environmental conditions. Our measure of % N stockpiled by each individual could have been influenced by cache layering if the transects for a given haypile happened to correspond with layers of particular plant functional groups (Jakopak et al, 2017). We doubt, however, that this would have introduced a consistent bias in our results, as we would have had an equal chance of sampling layers of high N foods (e.g., forbs) or low N foods (e.g., grasses), regardless of the plasticity that an individual expressed.…”

Section: Discussionmentioning

confidence: 99%

“…Every 5 cm along each transect, we recorded the species of the vegetation that touched the bottom of a pin flag. We then collected live samples of all cached plant species in proportion to their abundance (number of times encountered) along the transects (Hall & Chalfoun, 2018b;Jakopak, Hall, & Chalfoun, 2017). Plant samples were harvested from the meadow and talus areas immediately adjacent to the haypile (Huntly, 1987;McIntire & Hik, 2005) and were combined into a single, multi-species sample for analysis.…”

Section: Cache Qualitymentioning

confidence: 99%

“…We then collected live samples of all cached plant species in proportion to their abundance (number of times encountered) along the transects(Hall & Chalfoun, 2018b;Jakopak, Hall, & Chalfoun, 2017). The two remaining transects were read in the middle and the bottom portions of the haypile to sample the overall composition of the cache.…”

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confidence: 99%

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Behavioural plasticity modulates temperature‐related constraints on foraging time for a montane mammal

Hall

Chalfoun

2018

Journal of Animal Ecology

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Contemporary climate change is altering temperature profiles across the globe. Increasing temperatures can reduce the amount of time during which conditions are suitable for animals to engage in essential activities, such as securing food. Behavioural plasticity, the ability to alter behaviour in response to the environment, may provide animals with a tool to adjust to changes in the availability of suitable thermal conditions. The extent to which individuals can alter fitness‐enhancing behaviours, such as food collection, to proximately buffer variation in temperature, however, remains unclear. Even less well understood are the potential performance advantages of flexible strategies among endotherms. We examined the degree to which individuals altered rates of food collection in response to temperature, and two potential benefits, using the American pika (Ochotona princeps), a temperature‐sensitive, food‐hoarding mammal, as a model. From July–September 2013–2015, we used motion‐activated cameras and in situ temperature loggers to examine pika food‐caching activity for 72 individuals across 10 sites in the central Rocky Mountains, USA. We quantified % nitrogen by cache volume as a metric of cache quality, and the number of events during which pikas were active in temperatures ≥25°C as a measure of potential thermoregulatory stress. We found a strong negative effect of temperature on the rate at which pikas cached food. Individual responses to temperature varied substantially in both the level of food‐collecting activity and in the degree to which individuals shifted activity with warming temperature. After accounting for available foraging time, individuals that exhibited greater plasticity collected a comparable amount of nitrogen, while simultaneously experiencing fewer occasions in which temperatures eclipsed estimated thermal tolerances. By varying food‐collection norms of reaction, individuals were able to plastically respond to temperature‐driven reductions in foraging time. Through this increased flexibility, individuals amassed food caches of comparable quality, while minimizing exposure to potentially stressful thermal conditions. Our results suggest that, given sufficient resource quality and availability, plasticity in foraging activity may help temperature‐limited endotherms adjust to climate‐related constraints on foraging time.

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Section: Discussionmentioning

confidence: 99%

Section: Cache Qualitymentioning

confidence: 99%

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Behavioural plasticity modulates temperature‐related constraints on foraging time for a montane mammal

Hall

Chalfoun

2018

Journal of Animal Ecology

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“…Cheatgrass comprised nearly all of the invasive plant cover measured by our surveys and has degraded ecosystem function and negatively impacted small-mammal communities across the ecoregion (Freeman et al 2014). Plant communities with a high ratio of graminoids and low overall species evenness may represent an unstable, poor-quality source of nutrition, especially detrimental for lateseason foraging and haypile production (Jakopak et al 2017). In addition to these effects, cheatgrass primarily affects herbivores by (1) markedly increasing the fire frequency in a given community (D'Antonio and Vitousek 1992); and (2) senescing early in the summer-fall season and becoming mechanically and chemically poor in forage quality (Young and Allen 1997).…”

Section: Ecosystem or Plant-community Function Hypothesis Groupmentioning

confidence: 99%

“…However, at both levels, species evenness improved significantly when combined with the ratio gram: chem, even becoming the third-ranked model at the site level. Plant communities with a high ratio of graminoids and low overall species evenness may represent an unstable, poor-quality source of nutrition, especially detrimental for lateseason foraging and haypile production (Jakopak et al 2017). Relative cover of invasive species appeared in the top two model combinations at the site level, potentially reflecting the pervasiveness of invasive cheatgrass within individual sites.…”

Section: Ecosystem or Plant-community Function Hypothesis Groupmentioning

confidence: 99%

Evaluating mechanisms of plant‐mediated effects on herbivore persistence and occupancy across an ecoregion

2019

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Citation: Wilkening, J. L., E. J. Cole, and E. A. Beever. 2019. Evaluating mechanisms of plant-mediated effects on herbivore persistence and occupancy across an ecoregion. Ecosphere 10(6):Abstract. Contemporary climate change is rapidly creating one of the greatest challenges for management and conservation during the 21st century. Mountain ecosystems, which have a high degree of spatial heterogeneity and contain numerous habitat specialists, have been identified as particularly vulnerable. We used data from multiple years across sites spanning a >40 million ha ecoregion to test hypotheses regarding how community-level characteristics of vegetation may affect a mammalian generalist herbivore, the American pika (Ochotona princeps). We examined patterns of pika persistence across sites in the hydrographic Great Basin, and occupancy within a subset of these sites. We used mixed-effects logistic regression models to compare evidence in support of competing explanations for each pattern within an informationtheoretic framework (using Akaike's information criterion). Models reflected four hypothesized classes of mechanisms related to nutritional ecology, ecosystem function, indirect indication of climatic effects, and (synergistic) combinations of these three classes. At the site level, models reflecting synergistic effects received the most support. At the within-site level, support appeared to be split equally among hypotheses containing predictors related to either nutritional ecology or indirect climate effects. Well-supported predictors included cover of invasive plant species, cover of more-xeric plant species, species evenness, and proportion of graminoid species. Our results both (1) identify important aspects of vegetation communities that may influence herbivore distribution in mountainous areas across a large, diverse geographic region, and (2) contribute to an improved understanding of how mountain ecosystems may be affected by ongoing climate change, more broadly.

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Sampling a pika's pantry: Temporal shifts in nutritional quality and winter preservation of American pika food caches

Varner,

Carnes‐Douglas,

Monk

et al. 2023

Ecosphere

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Climate change is increasing temperature, decreasing precipitation, and increasing atmospheric CO2 concentrations in many ecosystems. As atmospheric carbon rises, plants may increase carbon‐based defenses, such as phenolics, thereby potentially affecting food quality, foraging habits, and habitat suitability for mammalian herbivores. In alpine habitats, the American pika (Ochotona princeps) is a model species for studying effects of changing plant chemistry on mammals. To survive between growing seasons, pikas cache “haypiles” of plants rich in phenolics. Although they are toxic to pikas, phenolic compounds facilitate retention of plant biomass and nutrition during storage, and they degrade over time. Alpine avens (Geum rossii, Rosales: Rosaceae) is a high‐phenolic plant species that comprises up to 75% of pika haypiles in Colorado. Here, we tested the hypothesis that contemporary climate change has affected the nutritional value of alpine avens to pikas in the last 30 years. Specifically, we compared phenolic activity, nutritional quality, and overwinter preservation of plants collected at Niwot Ridge, Colorado (USA), in 1992 to those collected between 2010 and 2018, spanning nearly three decades of climate change. Phenolic activity increased in alpine avens since 1992, while fiber and nitrogen content decreased. Importantly, overwinter preservation of plant biomass also increased, particularly on windblown slopes without long‐lasting snow cover. Previous studies indicate that pikas at this site still depend on alpine avens for their winter food caches. Higher phenolic content in alpine avens could therefore enhance the preservation of haypiles over winter; however, if pikas must further delay consuming these plants to avoid toxicity or invest extra energy in detoxification, then the nutritional gains from enhanced preservation may not be beneficial. This study provides important insights into how climate‐driven changes in plant chemistry will affect mammalian herbivores in the future.

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Organizing the pantry: cache management improves quality of overwinter food stores in a montane mammal

Cited by 7 publications

References 28 publications

Behavioural plasticity modulates temperature‐related constraints on foraging time for a montane mammal

Behavioural plasticity modulates temperature‐related constraints on foraging time for a montane mammal

Evaluating mechanisms of plant‐mediated effects on herbivore persistence and occupancy across an ecoregion

Sampling a pika's pantry: Temporal shifts in nutritional quality and winter preservation of American pika food caches

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