The influence of mine reclamation and highway reconstruction activities on grizzly bear habitat selection in the Cooke City basin, Montana

Abstract

The grizzly bear (Ursus arctos) population of the Greater Yellowstone Ecosystem is increasing in numbers and expanding its range. In this scenario, the number of conflicts between humans and grizzly bears is likely to increase. Understanding how grizzly bear habitat selection is affected by concentrated high human use, such as construction projects, plays a major role in management decisions for this species. In this research, we combined bear sign data collected in 27 permanent transects during 11 years (1990-91, 1996-97, 2003-04, and 2007-11) with food habits analysis to provide a description of grizzly bear habitat use in 91km 2 of the Cooke City Basin, Montana. Data were collected during years of mine reclamation (2003-04), highway reconstruction (2007-09), and years when no major human activities occurred (1990-91, 1996-97, and 2010-11). The main objectives of this study were to quantify grizzly bear spatial avoidance to mine reclamation and highway reconstruction activities and provide knowledge about environmental factors influencing grizzly bear habitat in the Basin. Resource selection functions were used to address these goals. Results showed that, in the Cooke City Basin, grizzly bears selected for mid-high elevation, forested, south-west facing slopes (areas where whitebark pine seeds are most abundant) and avoided areas of high tertiary road density. Mine reclamation occurred near whitebark pine forests. The estimated grizzly bear use of areas within 1 km and 2 km of reclamation epicenters decreased 83% and 52%, respectively, in years of mine reclamation. Grizzly bears did not avoid areas beyond 2 km of mine reclamation or areas within 4 km of highway reconstruction in years when these activities occurred. The lack of avoidance associated with highway reconstruction is likely explained by the fact that this occurred in the lowest elevation areas (below 2500 m) that are used less by grizzly bears. Grizzly bears use in the Cooke City Basin were mostly uninterrupted by two major construction projects. However, temporary and localized habitat loss occurred when construction was focused near whitebark forests with high bear use. Temporary habitat loss was not observed when construction occurred in areas distant from whitebark forests and used less by bears.