Impacts of Fire on Snowshoe Hares in Glacier National Park, Montana, USA

L Scott Mills,Karen E Hodges,Ellen Cheng

doi:10.4996/fireecology.1102119

Abstract

AbstractForest fires fundamentally shape the habitats available for wildlife. Current predictions for fire under a warming climate suggest larger and more severe fires may occur, thus challenging scientists and managers to understand and predict impacts of fire on focal species, especially species of management concern. Snowshoe hares (Lepus americanus Erxleben) are a common and important prey animal in boreal forests and are the primary prey for the US federally threatened Canada lynx (Lynx canadensis Kerr), so understanding hare dynamics in post-fire landscapes is critical for managing lynx. We collected habitat and fecal pellet data from 114 sites across three natural burn treatments (mature forest, 1988 Red Bench burn, and 1994 Adair and Howling burns) to evaluate impacts of fire and fire-habitat interactions on snowshoe hare in Glacier National Park, Montana, USA. We found that hare numbers were low throughout the park, with hares absent at 17 % of surveyed sites and occurring at densities above 0.5 hares ha−1 (a commonly suggested threshold for supporting Canada lynx) at only 7 % of sites. Hare densities were variable but 10 to 20 times higher in regenerating lodgepole pine (Pinus contorta Douglas ex Loudon) stands of 1988 Red Bench burn compared to lodgepole stands in other burn treatments. In stands dominated by other tree species, we found little difference in hare densities across burn treatments. Regardless of burn history or dominant canopy type, percent canopy cover was positively associated with hare relative abundance. Hare densities also increased with percent understory cover up to 80 % cover, beyond which they began to decline. The regular occurrence of wildfires in Glacier National Park, with 2003 being a particularly large fire year (the largest since 1910), suggest that hare and lynx distribution and abundance within the park may shift substantially in the coming decades as these animals respond to changing spatiotemporal patterns of regenerating forest.

Highlights

Wildfires are a dominant disturbance in coniferous forests across Canada and the United States (Baker 2009, Marlon et al 2012, Archibald et al 2013)
Our research focused on hare use of the 1988 Red Bench Fire, which burned over 13 000 ha of primarily lodgepole pine forest in the park’s northwest corner, and on the 1994 Adair and Howling fires, which burned 340 ha along the park’s western edge
Snowshoe hares occurred at low densities and were patchily distributed in Glacier National Park

Summary

Introduction

Wildfires are a dominant disturbance in coniferous forests across Canada and the United States (Baker 2009, Marlon et al 2012, Archibald et al 2013). Forest mammals often respond strongly to post-fire habitats (Fisher and Wilkinson 2005, Fontaine and Kennedy 2012), but for many species, post-fire responses through time remain poorly characterized, as do the attributes of regenerating post-burn landscapes that enable use or persistence (Spies et al 2012). In 1988, large stand-replacing fires in Yellowstone National Park, Wyoming, USA, converted mature forest stands that probably supported lynx into early seral stands that could not support lynx (Murphy et al 2006). Throughout their range, lynx presence coincides with densities of snowshoe hares (Lepus americanus Erxleben), their primary prey (Ruggiero et al 2000). To understand lynx distribution and dynamics requires knowledge of hare distribution and dynamics

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