Seeking snow and breathing hard – Behavioral tactics in high elevation mammals to combat warming temperatures

Abstract

The world glaciers and areas of persistent summer snowpack are being lost due to warming temperatures. For cold-adapted species, habitat features may offer opportunities for cooling during summer heat yet the loss of snow and ice may compromise derived thermoregulatory benefits. Herein we offer insights about habitat selection for snow and the extent to which other behavioral adjustments reduce thermal debt among high elevation mammals. Specifically, we concentrate on respiration in mountain goats (Oreamnos americanus), a species whose native distribution is currently tied to northern mountain ranges of North America, where large patches of persistent summer snow are declining, and which became extinct during geologically warmer epochs. To examine sensitivity to possible thermal stressors and use of summer snow cover, we tracked marked and unmarked mountain goats in Glacier National Park, Montana, USA, to test hypotheses about selection for cold microclimates including shade and snow during periods of relatively high temperature. To understand functional responses of habitat choices, we measured microhabitat temperatures and a component of goat physiology–breaths per minute–as an index for metabolic expenditure. Individuals 1) selected areas closer to snow on warmer summer days, and 2) on snow had a 15% mean reduction in respiration when accounting for other factors, which suggests remnant snow plays an important role in mediating effects of air temperature. The use of shade was not as an important variable in models explaining respiration. Despite the loss of 85% of glaciers in in Glacier National Park, summer’s remnant snow patches are an important reservoir by which animals reduce heat stress and potential hyperthermia. Our findings, when contextualized with behavioral strategies deployed by other high elevation mammalian taxa help frame how ambient temperatures may be modulated, and they offer a direct way by which to assess susceptibility to increasing heat in cold-adapted species.

Temperature shapes movement and habitat selection by a heat-sensitive ungulate

“…Other ungulates may use different features of the landscape to mitigate heat stress. For example, mountain goats (Oreamnos americanus) may move closer to persistent snow cover during hot weather rather than seeking shade (Sarmento et al 2019).…”

Space Use and Seasonal Movement of Isolated Mountain Goat Populations in the North Cascades, WA

“…Warmer temperatures during the last 30 years have affected the function and composition of ecological communities and the phenology and distribution of many species [51]. Mountain goats lack the exibility of other large mammals to adapt to rising temperatures and a dependence on snowy habitat puts their populations at risk [52]. Furthermore, little is known about how a changing climate might affect the social dynamics of mountain goat populations, especially those with limited immigration and emigration.…”

Daily torpor reduces the energetic consequences of habitat selection for a widespread bat

“…At ambient temperatures that exceed the thermoneutral zone, homeotherms select areas of the landscape where they can increase heat loss (McCann et al 2016, Sarmento et al 2019 or reduce heat gain from the environment (Hovick et al 2014, Alston et al 2020).…”