Growth in Common Raven Populations
It has been hypothesized that Common Raven populations were suppressed due to historic human persecution and the removal of bison and wolves; both have now returned to Jackson Hole. Are these large mammals attracting ravens? While elk, deer and bison numbers have increased over the past 55-years, the raven population has incresed by 600 percent. Do these statistics imply a healthy or a stressed population? While the ecosystem may appear advantageous for nesting ravens, the harsh climate and unpredictable food resources may suppress nesting success. In 2002, Craighead Beringia South initiated a long-term study of the ecology of the Common Raven in Jackson Hole. The primary effort during the first three years is to document fledgling mortality and dispersal. Concomitantly, we are documenting other influences on raven mortality. These may include nest site competition, productivity, roosting ecology, feeding habits and the occurance of West Nile Virus. To understand the roll this scavenger and predator plays in the ecology of the Upper Snake River Ecosystem, we must also understand the population dynamics of the raven’s often unpredictable food sources, elk, bison, Uinta ground squirrels, insect populations and human refuse.
Objectives
The goal of the Raven Project is to gather, in part, the scientific information that will provide us with the knowledge to wisely manage the Greater Yellowstone Ecosystem. The specific objectives are:
To determine if the raven population is now stable, increasing or decreasing.To document the rate of post-fledgling mortality and determine the causes.To understand how fluctuating food sources effect survivorship and ultimately population dynamics of this bird species.Understand the anthropogenic influences on this population.Map annual home ranges and movements of juvenile and adult ravens using GPS technology.
Personnel
The Raven Projectinvestigators include Derek Craighead, Bryan Bedrosian, Trapper Haynam, andCrew1of Craighead Beringia South.
Cooperators
The Raven Project works closely and in accordance with a variety of cooperators, collaborators, and permitting agencies and organizations, including Grand Teton National Park, Wyoming Game and Fish Department, Wyoming State Veterinary Lab, and Arkansas State University, Biology Department.
Recent Publications
Bedrosian, B. E. and D. Craighead. 2007. Evaluation of transmitter attachment techniques for large-altricial fledglings. Northwest Naturalist. 88:1-6. PDF
Bedrosian, B. and D. Craighead. 2007. Band wear in Common Ravens (Corvus corax). North American Bird Bander. 32:149-152. PDF
Bedrosian, B., J. Loutsch,and D. Craighead. 2008. Using morphometricsto determine the sex of Common Ravens. Northwest Naturalist. 89:46-52. PDF
Funding
The Raven Project is funded by grants and donations from organizations and individuals interested in the proper management, conservation, and stewardship of our natural resources, including wildlife. All donations are tax-deductible and Craighead Beringia South is a registered non-profit.