Influence of wind on movement behaviour in Arctic grizzly bears.

Abstract

Odours are emitted from organic matter and can contain important information about an animal's surroundings, including the presence and location of other organisms. Wind acts as a conduit of olfactory information, affecting the spread and direction of odour dispersal across terrestrial landscapes. To increase the likelihood of detecting an odour molecule, individuals may exhibit anemotaxis - orientation bias to wind during movement - where the theoretical optimal olfactory search strategy is to move crosswind. We tested for biased movement relative to wind in Arctic grizzly bears (Ursus arctos) during the spring hypophagic period in the Mackenzie Delta, Northwest Territories, Canada using modelled winds and satellite-linked telemetry data (n = 12,430 locations) from 40 Arctic grizzly bears monitored between 2003 and 2010. Our results show that orientation relative to wind varied with movement rate, a proxy for active search effort. During steps where bears had high movement rates (> 90th percentile), bears predominantly oriented crosswind. We also found a positive relationship between movement rate and crosswind orientation: as bears moved faster, they increased their crosswind component of orientation. These results suggest an adaptive pattern of movement in response to wind, where bears oriented relative to the wind in a way that increased the likelihood of odour detection during active search. We suggest that future studies could include wind data in habitat selection and foraging models to examine its influence on habitat selection and use.