Pronghorn, Wolf, and Coyote Dynamics

WCS involvement in the West began nearly 100 years ago with a campaign to preserve the bison, and WCS conservation and research continues today in the quintessential wilderness of Greater Yellowstone.  One of the most intact mountain environments in the continental United States, Greater Yellowstone supports an unequaled diversity of large mammals.  This project seeks to investigate the interrelationships among coyote, wolf, and pronghorn antelope populations in Greater Yellowstone.
 
The Human Aspect
Humans have a significant impact in the Greater Yellowstone area.  Residential development is infringing on pronghorn summer range and parts of their migration route. Energy development has exploded in pronghorn winter range, increasing roads, fences, and human activity. 

Threats
Since the early 1990s, pronghorn numbers in the Jackson Hole area have declined to approximately 200.  Coyotes are a major predator of pronghorn fawns and may be contributing to this decline.  The reintroduction and expansion of wolves in the region may also impact coyotes and the pronghorn antelope population.  Thus, understanding predator dynamics is critical to conserving Grand Teton National Park’s pronghorn population.

WCS Activities
WCS is a wildlife research and conservation organization that seeks and uses science-based information to work collaboratively with a wide variety of public and private stakeholders.  The pronghorn project began in 2001 to gain an understanding of both human-related and natural threats to the maintenance of a viable pronghorn population.  Research is evaluating pronghorn pregnancy rates, fawn survival, and the causes of mortality in relation to coyotes, the presence and absence of wolves, and human development.  Researchers will compare pronghorn fawn survival and coyote densities in areas frequented by wolves with other areas where wolves are largely still absent.  This will allow us to evaluate how recolonizing wolves, which tend to reduce coyote densities, may impact pronghorn fawn survival.  WCS seeks to address low fawn survival rates by examining cascading effects of wolves on coyotes and pronghorn in and adjacent to Grand Teton National Park.  In other words, coyotes may have a much larger impact on pronghorn populations in the absence of wolves than in areas where wolves have reestablished — a phenomenon known as meso-carnivore release. 

Important Next Steps

• Place radio-tracking collars on fawns and monitor fawns from ground and air both
  on summer and winter ranges.
• Evaluate fawn recruitment and survival rates in relation to coyotes, wolves, and
  human development.
• Document population movement patterns and the effect both natural and human-
  related disruptions have on biological corridors.
• Provide key information to diverse audiences to facilitate stronger cooperation
  among agencies involved in the protection of this pronghorn population and
  remnant migratory pathway. 
• Coordinate with pronghorn migration corridor conservation study (see Pronghorn
  Migration Conservation fact sheet) to share information and maximize impacts.
  

Selected and representative publications


peer-reviewed journal publications
Berger, J. The Last  Mile:  How to Sustain Long Distance Migration
     in Mammals.  Conservation Biology   18(2):320-331.
Pyare, S., S. L. Cain, D. Moody, C. Schwartz, and J. Berger.  Grizzly
     bears in the Yellowstone Ecosystem; Loss and Re-colonization Rates
     during a Century of Change.  Animal Conservation  7:1-7.
Berger, J. 2003.  Is it Acceptable to Let a Species go Extinct in a
     National Park?  Conservation Biology 17: 1451-1454. 
Berger, J.  2003.  Through the Eyes of Prey: How the Extinction and
     Conservation of North America’s Large Carnivores Alter Prey Systems
     and Biodiversity.  Pp 133-156, In Animal Behavior and Wildlife Conservation
     (eds. M. Festa-Bianchet and M. Apollonio). Island Press, Covello, CA).
Pyare, S. and J. Berger.  2003.  Beyond demography and delisting: ecological
     recovery for Yellowstone’s Grizzly Bears and Wolves.  Biological Conservation
     113:63-73.
Berger, J. 2002.  Wolves, Landscapes, and the Ecological Recovery
     of Yellowstone.  Wild Earth12:32-37.
Berger, J. and K. Berger. 2001.  Endangered Species and the decline of
     America's Western Legacy?  Bioscience  51:951-953.
Berger, J., J. E. Swenson, and I. Per-Illson.  2001.  Re-colonizing Carnivores
     and Naive Prey; Conservation Lessons from Pleistocene Extinctions. 
     Science 291:1036-1039.
Berger, J. P. B. Stacey, M. L. Johnson, and L. Bellis.  2001. A Mammalian
     Predator-Prey Imbalance: Grizzly Bear and Wolf Extinction Affects Avian
     Neotropical Migrants.  Ecological Applications 11:947-960.
Berger, J.  1999.  On Intervention and the Persistence of Small Populations
     of Bighorn Sheep.  Conservation Biology 13:432-435
Berger, J.  1991.  Greater Yellowstone's Native Ungulates: Myths and
     Reality.  Conservation Biology  5:353-363.

Books
Cunningham, C. and J. Berger.  1997.  Horn of Darkness: Rhinos on the Edge.
     Oxford University Press.
Berger, J. and C. Cunningham.  1994.  Bison: Mating and Conservation
     in Small  Populations. Columbia University Press. 
Berger J.  1986.  Wild Horses of the Great Basin: Social Competition
     and Population Size.   University of Chicago Press, Chicago.