Variation in seasonal movements, habitat selection, and demographics of an irruptive, facultative migrant

Abstract

Understanding how organisms respond to environmental variation is a primary goal in ecology, especially considering the rate and magnitude of anthropogenic change occurring worldwide. The extent to which facultative movements function in response to constraining conditions is unclear, and empirical examination of the proximate cues eliciting facultative behavior is limited. This study tests whether winter facultative movements by Great Gray Owls (GGOWs) in the Greater Yellowstone Ecosystem occur in response to constraining snow conditions, and how these conditions impact fitness.  We outfitted GGOWs (n=40) with GPS transmitters, monitored reproductive output, and surveyed breeding-season prey abundance between 2014-2021.  We will analyze movements and habitat selection using Net Square Displacement models, Resource Selection Functions, and analyses will incorporate remotely-sensed weather, geophysical, and landscape covariates.  We will assess fitness metrics in relation to within-season prey abundance versus carry-over effects from the prior winter using Generalized Linear Mixed Models.  Evaluation of facultative systems can indicate how animals use plasticity in movement behavior to cope with environmental change. This work also will identify determinants of fitness for a facultative migrant species, which is critical for understanding population dynamics in such systems.

Featured photo by Yellowstone National Park on Flickr (https://flic.kr/p/S519ZL).