FY2005 Task 9.06
Virginia Museum of Natural History
Avian Habitat Restoration on the Virginia Barrier Islands:Test of a Non-Lethal Approach to Predation Management
Project Description as Proposed:
Removal of raccoons and red foxes is now employed as a tool for avian habitat restoration on the Virginia barrier islands by the US Department of Agriculture. The proposed research for this task will assess the results of this predation management and test the use of an estrogen-induced food aversion to reduce raccoon predation on bird eggs. VMNH is running a pen trial with captive raccoons (through FY 2004 Task 11.09), to test previous claims about the efficacy of this technology. They may also run a small-scale field trial through FY 2004 Task 11.09, to determine the feasibility, practicality and potential expense of implementing such management. Depending on the outcome of these trials, VMNH will implement either a revised experimental field trial or a full-scale management application of this technology on perhaps 2-4 barrier islands during summer 2006.
The Principal Investigator, Ray Dueser, holds a 2 year permit from the Virginia Department of Game and Inland Fisheries for scientific collections. This permit authorizes the holder to collect and treat raccoons with oral estrogen in field trials in Northampton and Accomack Counties, the two counties within which the seaside barrier islands lie. The permit expires December 31, 2006.
Nancy D. Moncrief, (276) 666-8614; email@example.com
Final Product Received:
Science-Based Conservation Management
on the Virginia Barrier Islands:
Avian Habitat Restoration Through Predation Management
By Raymond D. Dueser, Utah State University; Nancy D. Moncrief, Virginia Museum of Natural History; Joel D. Martin, Utah State University
February 1, 2007
Final Report PDF
Project Summary Provided by Grantee:
During May- August 2006, Virginia Museum of Natural History (VMNH) and Utah State University (USU) personnel conducted both a pen trial of the efficacy of estrogen-based aversive conditioning with captive raccoons and a pilot field trial with free-ranging raccoons in summer 2006. Tentative results of the pen trial indicate that 1) oral estrogen can be effectively deployed through injection in Japanese quail eggs, 2) raccoons develop an aversion to egg consumption following ingestion of eggs injected with oral estrogen, and 3) estrogen consumption has no adverse health effects for raccoons.
The pilot field trial was conducted on the bird-free Skidmore Island section of Eastern Shore of Virginia National Wildlife Refuge. VMNH and USU personnel fitted raccoons with a large numbered and color-coded tag in each ear (for photographic identification) and a radio collar. Artificial "nest" colonies were established and depredation events were monitored with automatic cameras. More than 2,000 photographs of individually recognizable raccoons were accumulated, and movement patterns of eleven individual animals were monitored over a 51-day period in June, July, and August 2006.
Analyses of the field trial data indicates that: (1) all radio-collared raccoons became averted to egg consumption, in part because raccoons cannot distinguish treated from non-treated eggs, (2) the aversion lasted for at least 26 days, (3) averted raccoons altered their foraging behavior to visit "colony" areas less frequently and to visit fewer colonies, and (4) egg consumption declined significantly in all colonies.
Overall conclusions are that the estrogen aversion was real, it influenced the foraging activity of individual raccoons, and it lasted long enough to bridge the avian egg-laying period. Predation management remains a useful method to enhance and restore avian nesting habitat on the Virginia barrier islands. Trapping-and-removal has proven effective in reducing raccoon and red fox numbers on several islands. In reality, however, removals are seldom complete; it is common for 1-3 raccoons to remain on an island (or to re-colonize an island very quickly) even after a productive removal program. Aversive conditioning appears to hold substantial promise for reducing depredation by predators on any island having low numbers of predators, either naturally or following a trapping campaign. Predation management is both more feasible and more effective as a conservation strategy on the Virginia barrier islands than has been reported from several studies conducted on extensive mainland areas elsewhere in North America.
Disclaimer: This project summary provides the federal dollars initially awarded to the grantee. Due to underexpenditure or reprogramming of grant funds, this figure may change. For more information on the allocation of coastal grant funds, please contact Laura McKay, Virginia Coastal Program Manager, at 804.698.4323 or email: Laura.McKay@deq.virginia.gov
A more detailed Scope of Work for this project is available. Please direct your request for a copy to Virginia.Witmer@deq.virginia.gov