Contrasting daily and seasonal activity and movement of sympatric elk and cattle

Authors: Clark, Pat; JOHNSON, DOUGLAS - Oregon State University; JOHNSON, MICHAEL - Harvard University; Ganskopp, David; VAVRA, MARTIN - Us Forest Service (FS); COOK, JOHN - National Council For Air & Stream Improvement (NCASI), Inc; COOK, RACHEL - National Council For Air & Stream Improvement (NCASI), Inc; Pierson Jr, Frederick; Hardegree, Stuart

Submitted to: Rangeland Ecology and Management
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/13/2016
Publication Date: 2/17/2017
Citation: Clark, P., Johnson, D., Johnson, M.D., Ganskopp, D.C., Vavra, M., Cook, J.G., Cook, R.C., Pierson, F.B., Hardegree, S.P. 2017. Contrasting daily and seasonal activity and movement of sympatric elk and cattle. Rangeland Ecology and Management. 70(2):183-191.

Interpretive Summary: A better understanding of how sympatric elk and cattle behave at fine scales is needed to properly manage and allocate resources for these species. We addressed this knowledge gap using intensively-sampled GPS tracking data (1-sec intervals) to classify elk and cattle behavior and investigate their fine-scale activity and movement strategies in the Blue Mountains of northeastern Oregon, USA, during summer and fall 2007. Sympatric elk and cattle exhibited differing activity and movement strategies during both summer and fall. These findings lend support to the hypothesis that elk and cattle occupy differing dietary niches thus moderating the potential for direct interspecific competition during summer and fall.

Technical Abstract: Elk (Cervus elaphus L.) and cattle (Bos taurus L.) co-occur on range and forest lands throughout much of western North America. The literature regarding range relations between elk and cattle is, however, highly contradictory describing strong evidence of interspecific competition in some cases and complementary or facilitative relations in others. Unfortunately, our understanding of these relations has largely been based on relatively coarse spatiotemporal data inadequate to effectively sort out the complexities of this issue. A better understanding of how sympatric elk and cattle behave at fine scales is needed to properly manage and allocate resources for these species. We addressed this knowledge gap using intensively-sampled GPS tracking data (1-sec intervals) to classify elk and cattle behavior and investigate their fine-scale activity and movement strategies in the Blue Mountains of northeastern Oregon, USA, during summer and fall 2007. We used an ensemble classification approach to identify stationary, foraging, and walking behavior classes within the GPS datasets of mature beef and captive elk cows grazing in forested pastures during two randomized experiments, one in summer and the other fall. During summer, elk traveled further per day, had larger walking budgets, exhibited more and longer walking bouts, and had higher walking velocities than beef cows. Cattle tended to emphasize intensive foraging over extensive movement and thus displayed larger foraging budgets and longer foraging bouts than elk. During fall, when forage quality was limiting, elk exhibited a more foraging-centric mobility strategy while cattle emphasized a strategy of energy conservation. These differing movement and energetic strategies tended to support the concept that elk and cattle occupy differing dietary niches during summer and fall. Extensive foraging by elk and intensive foraging by cattle during summer correspond well with behaviors expected for elk searching out forbs in graminoid-dominated habitats and with intensive foraging for graminoids by cattle. Behaviors exhibited in the fall were consistent with elk continuing to exercise more selectivity among the available forage than cattle. These differing strategies, consequently, would moderate the potential for direct interspecific competition during summer and fall.