Assessing site-use and sources of disturbance at walrus haul-outs using monitoring cameras

Abstract

The rapid growth of tourism in Polar Regions stimulates a need for investigating potential impacts on targeted species and sensitive areas. This study examines effects of tourist visitations on haul-out dynamics and site use by walruses (Odobenus rosmarus) in Svalbard, Norway. Automated camera stations were established at five traditional haul-out sites that experience variable levels of tourist visitation. The cameras took one photograph each hour, throughout June–November from 2007 to 2015 (3 sites) and 2010–2015 (2 additional sites). A total of 66,365 images were analysed. The approximate number of walruses on shore, and % sea-ice cover was estimated for each image; additionally, the presence/absence of tourists, boats and polar bears (Ursus maritimus) were recorded. A log-linear regression model was run on residuals from an ARIMA model, fitted to each season of counts from each site. Use of the terrestrial haul-out sites was sometimes restricted by sea-ice cover, but walruses were also absent (or present rarely) at some sites, despite a lack of sea ice. Tourists on land and boats near the haul-out sites (with a single exception) did not disturb walrus haul-out behaviour significantly (p > 0.05) at any of the sites. In addition, most polar bear visits were not associated with detectable disturbances. However, polar bears did significantly disturb walrus herds at Andreetangen (p = 0.003) and Storoya (p = 0.002) in some years. These disturbances were likely associated with predation attempts on calves.