Abstract
Migration functions as an adaptive strategy to improve fitness by allowing individuals to exploit spatiotemporal gradients of resources. Yet migration, especially among large ungulates, is increasingly threatened by human activities, making it necessary to understand variation in migratory behavior. We identified different movement strategies for pronghorn (Antilocapra americana) at the northern limit of the species’ range, and tested hypotheses for variation between migratory behaviors. From 2003–2010, we captured 185 female pronghorn across Alberta and Saskatchewan, Canada, and Montana, USA. We identified discrete migratory behaviors, including seasonal migration, facultative winter migration, potential post-fawning migration, and the use of stopover sites. Fifty-five percent of individuals undertook seasonal migrations, and we recorded the longest reported round-trip migration for the species at 888 km. Some (22%) seasonal migrations included ≥1 stopover sites, with significantly greater use of stopovers during spring than fall. Migrants (34%) and residents (20%) undertook facultative winter migrations, with the majority (68%) undertaken by migrants. Additionally, 12% of individuals exhibited potential post-fawning migrations. For each season, we estimated a suite of movement metrics and used multivariate statistics to compare movement similarities across migration behaviors. Correspondence analyses revealed 3 groupings of migration behavior. Spring migration was its own grouping, characterized by more sinuous and slower movements, consistent with the forage maturation hypothesis. Fall migration, facultative winter migration, and potential post-fawning migration clustered in a single group that displayed linear, fast movements, consistent with being influenced by ecologically limited resources such as severe winters or predation avoidance. Lastly, spring and fall stopover sites were grouped together as a means to use high-quality forage during migration, also consistent with the forage maturation hypothesis. At the northern periphery of pronghorn range, differences between migratory behaviors are influenced by various ecological factors, merit increased attention, and contribute to overall persistence.
| Original language | English |
|---|---|
| Pages (from-to) | 1229-1242 |
| Number of pages | 14 |
| Journal | Journal of Wildlife Management |
| Volume | 82 |
| Issue number | 6 |
| DOIs | |
| State | Published - Aug 2018 |
Funding
Thompson in Montana; C. Lees and J. Pogorzelec in Saskatchewan for field assistance and logistical support. We thank P. M. Lukacs for providing analytical assistance, and comments from K. L. Montieth and 2 anonymous reviewers on previous versions of the manuscript. We also thank Allison Air Service, Bighorn Helicopters, Inc., Hitch Aviation, Pathfinder Helicopter Wildlife Management, and Quicksilver Air for excellent capture and surveillance of pronghorn during the study. This study was funded by the Alberta Antelope Guides, Alberta Fish and Game Association (Zone 1), Alberta Professional Outfitters Society, Canadian Forces Base Suffield, Foundation for Northern American Wild Sheep − Eastern Chapter, Safari Club International, Safari Club International Alberta Chapter & Northern Alberta Chapter, Alberta Conservation Association (ACA), Petro-Canada, Sustainable Grasslands Applied Research program, Montana Fish, Wildlife & Parks (FWP), U.S. Bureau of Land Management (BLM), World Wildlife Fund (WWF), University o ACS–Accelerate Program, Alberta Sport Recreation Parks and Wildlife Foundation, Montana Chapter of The Wildlife Society, and Counter Assault. In-kind support was provided by The Miistakis Institute, FWP, ACA, BLM, and WWF. We thank D. J. Bender, J. P. N. Landry-Deboer, D. H. Eslinger, M. G. Grue, K. Morton, and M. J. Suitor in Alberta; J. C. Carlson, J. A. Gude, P. T. Gunderson, J. T. Herbert, K. R. Johnson, D. Jørgensen, M. G. Sullivan, and S. Thompson in Montana; C. Lees and J. Pogorzelec in Saskatchewan for field assistance and logistical support. We thank P. M. Lukacs for providing analytical assistance, and comments from K. L. Montieth and 2 anonymous reviewers on previous versions of the manuscript. We also thank Allison Air Service, Bighorn Helicopters, Inc., Hitch Aviation, Pathfinder Helicopter Wildlife Management, and Quicksilver Air for excellent capture and surveillance of pronghorn during the study. This study was funded by the Alberta Antelope Guides, Alberta Fish and Game Association (Zone 1), Alberta Professional Outfitters Society, Canadian Forces Base Suffield, Foundation for Northern American Wild Sheep − Eastern Chapter, Safari Club International, Safari Club International Alberta Chapter & Northern Alberta Chapter, Alberta Conservation Association (ACA), Petro-Canada, Sustainable Grasslands Applied Research program, Montana Fish, Wildlife & Parks (FWP), U.S. Bureau of Land Management (BLM), World Wildlife Fund (WWF), University o ACS–Accelerate Program, Alberta Sport Recreation Parks and Wildlife Foundation, Montana Chapter of The Wildlife Society, and Counter Assault. In-kind support was provided by The Miistakis Institute, FWP, ACA, BLM, and WWF.
| Funders |
|---|
| Hornocker Wildlife Institute/Wildlife Conservation Society |
| World Wildlife Fund |
| Bureau of Land Management |
| Alberta Conservation Association |
Keywords
- Antilocapra americana
- Northern Sagebrush Steppe
- facultative winter migration
- net squared displacement
- post-fawning migration
- pronghorn
- seasonal migration
- stopover sites