When is habitat recovered? Understanding the mechanisms of population decline to evaluate habitat recovery for boreal caribou

Abstract

Recovering habitat is a central objective for conserving species imperiled by habitat alteration. Yet, determining when habitat is recovered is challenging. For terrestrial wildlife, habitat recovery often focuses on regenerating vegetation, but vegetation changes may provide limited insight as to whether and when habitat is recovered. To be effective as a conservation action, habitat recovery should be linked to demographic responses of the focal species. Moreover, we suggest that habitat recovery be linked to changes in the strength of mechanisms driving population decline. Here, we illustrate such a framework using boreal woodland caribou (Rangifer tarandus caribou), which are threatened by altered predator–prey dynamics stemming from habitat alteration. Monitoring habitat recovery is challenging for boreal caribou because demographic effects may take decades to manifest and the spatial scale for demographic monitoring is larger than typical disturbance features or restoration projects. To address these challenges, we propose a continuum of habitat recovery where interim, multi-scale indicators are linked to primary mechanisms underlying caribou population declines. Because habitat recovery varies geographically, indicators may need to be refined on a regional basis. Developing stronger inferences on recovery indicators will require adaptive management, where habitat recovery is implemented over larger spatial extents and longer timeframes.