The effect of snow on space use of an alpine ungulate: recently fallen snow tells more than cumulative snow depth

Abstract

Snow is one of the most limiting environmental factors for large wildlife of temperate and arctic zones during winter. Snow depth may limit space use, increase energy expenditure related to movement, limit resource availability, and ultimately affect individual survival. Most of the studies on the effect of snow on animal space use have used cumulative snow depth. The amount of recently fallen snow, however, could be more relevant for wildlife, especially in alpine and northern environments, where wind shifts and hardens the snow cover constantly. From 2011 to 2013, we studied space use of mountain goats (Oreamnos americanus (Blainville, 1816)) within Jasper National Park in Alberta, Canada. During winter, daily and weekly movements decreased with the amount of recently fallen snow, but not with cumulative snow depth. These results indicate that recently fallen snow should be included in wildlife space-use studies during winter. Limited movement and range size of mountain goats also highlight the energy-saving tactic used in winter by this species.Résumé : Durant l'hiver, la neige est l'un des facteurs environnementaux les plus limitants pour la grande faune des régions tempérées ou arctiques. L'épaisseur de neige peut limiter l'utilisation de l'espace, augmenter les dépenses énergétiques liées aux déplacements, limiter la disponibilité des ressources et ultimement affecter la survie. La plupart des études concernant les effets de la neige sur l'utilisation de l'espace de la faune ont utilisé des mesures d'épaisseur de neige. Par contre, la quantité de neige fraiche pourrait être plus représentative des conditions rencontrées par la faune, particulièrement en région alpine ou arctique où le vent déplace et compacte constamment le couvert nival. De 2011 à 2013, nous avons étudié l'utilisation de l'espace des chèvres de montagne (Oreamnos americanus (Blainville, 1816)) dans le Parc national Jasper en Alberta, Canada. Durant l'hiver, les déplacements quotidiens et hebdomadaires, diminuaient en fonction de la quantité de neige fraiche, mais pas en fonction de l'épaisseur de neige au sol. Ces résultats indiquent que la neige fraiche devrait être incluse dans les études d'utilisation de l'espace de la faune durant l'hiver. Les déplacements limités et la petite taille des aires utilisées par les chèvres de montagne soulignent la tactique d'économie d'énergie utilisée par cette espèce durant l'hiver.

Mountain goat resource selection in relation to mining‐related disturbance

“…During winter, mountain goats experience severe energetic and nutritional challenges associated with availability and quality of food resources and, perhaps more importantly, high costs of locomotion in deep snow (Fox 1983, Dailey and Hobbs 1989, Fox et al 1989, White et al 2009. Consequently, mountain goats exhibit an extremely conservative bioenergetic strategy during winter that is characterized by restricted movement (White 2006, Richard et al 2014. Indeed, most mountain goat mortality occurs in late winter (White et al 2011) and in our study area was most often associated with malnutrition (White et al 2012b).…”

Seasonal resource selection by introduced mountain goats in the southwest Greater Yellowstone Area

“…The relative importance of steeper slopes in winter was also highlighted by the striking improvement in the top model with the post-hoc addition of DET. We suspect steeper slopes are selected in winter as a behavioral adaptation to avoid deep (or recently fallen; i.e., Richard et al 2014) snow, which is more readily shed in steep environments, and in so doing reduces the metabolic costs associated with movement and increases access to forge. Moreover, mountains goats also selected southwest aspects in winter, which further reduces snow accumulation due to increased solar radiation.…”

Space use analyses suggest avoidance of a ski area by mountain goats

“…Because we were interested in mountain goat space use, we accounted for variables influencing space use when defining season. Because snow is one of the main variables influencing mountain goat space use in winter (White , Poole et al , Richard et al b ), we determined that the beginning of summer would correspond to the period when snow was receding in the area. We defined summer as 1 May–14 October and winter as 16 December–30 April.…”