Dutch Gap Black Vulture Management
- Dutch Gap Vulture Background & Status
- Fall 2007 Black Vulture Management at Dutch Gap
- Monitoring & Research Efforts
- Black Vulture Facts
Seen a Tagged Vulture?
- 100 individuals have been tagged with orange wing markers bearing a unique three-digit code assigned to each individual, and then released. These markers are visible while the bird is perched and often are visible in flight.
- We encourage any wildlife enthusiasts who see these tagged vultures to report them via email. Please only report vultures that are tagged with orange or white wing markers.
- If possible, report the date, time of day, location, activity of the bird (feeding, roosting, loafing, flying), and the tag number.
Dutch Gap Vulture Background and Status
History of Black Vultures and property damage at Dutch Gap
- Black Vultures are known to have utilized the Dutch Gap area since the 1980s for roosting and loafing. During the 1990s, vulture use of the area increased significantly, possibly due to loss of preferred roost sites to residential and commercial development. In 1999, Black Vultures at the Dutch Gap boat ramp were documented damaging cars by scratching paint, pulling off windshield wipers and moldings, and tearing car covers; they also were leaving fecal matter and vomit on vehicles, boat trailers, and the boat landing grounds. The vultures also loafed and roosted on Virginia Power (now Dominion) power station facilities, creating a safety hazard due to excrement on walkways and other equipment.
History of Black Vulture control at Dutch Gap
Beginning around 2000, the Virginia Wildlife Services office of the U.S. Department of Agriculture (WS) assisted Dominion with vulture damage abatement by harassing vultures with pyrotechnics (i.e., handheld lasers and flares) and limited shooting to reinforce harassment.
- After repeated harassment attempts failed to disperse the vultures, in August 2002, WS trapped and euthanized 375 black vultures at Dutch Gap.
- In spring 2003, Chesterfield County implemented an extensive harassment program to disperse the vultures. Vultures were harassed in the evenings on the towers and at the landing in the mornings. Pyrotechnics were used to harass vultures at the affected buildings, transmission towers, and other roosting and loafing areas on both sides of the river. Dominion also installed electronic bird calls on the towers to dispel the vultures. The number of vultures roosting on the towers was reduced significantly after approximately two weeks and County personnel reported that, when the vultures did not roost overnight at the towers, neither were they present at the boat landing the next morning. Some County employees noticed that the vultures had moved to a spot just around the bend in the river and saw the birds roosting on the roof of a private residence. Two propane cannons provided by WS were placed on the Dominion towers and set on a timer so that they only fired during a 2-hour period at dusk. The cannons kept vultures from roosting on the towers but, after the cannons were removed, the vultures resumed use of the site within a few weeks.
- December 2003 - January 2004: WS trapped and euthanized 365 black vultures from Dutch Gap.
- In late summer/early fall 2004, WS implemented another extensive vulture harassment program. Using pyrotechnics, WS dispersed the black vultures roosting on the transmission towers and kept them away from the boat landing. The vultures, however, would attempt to return to the site very quickly if the harassment stopped. WS therefore purchased additional propane cannons and clock timers for use at the transmission towers. Dominion agreed to have their personnel refill the propane tanks and wind the clock timers as necessary. In January 2005, Dominion reported that the vultures ignored the propane cannons and did not leave the towers. They reported that the cannons were effective when first installed, but later were ignored.
- June - July 2005: WS harassed the Dutch Gap vultures using pyrotechnics, paintball guns, shooting, and effigies, but this effort failed to permanently disperse the birds.
- December 2005 - February 2006: WS trapped and euthanized 540 black vultures at the site. Twenty vultures were tagged and released. Three of these tagged vultures continue to be seen regularly at Dutch Gap.
Fall 2007 Black Vulture Management at Dutch Gap
Since the last WS trapping of vultures at Dutch Gap, the birds have returned in substantial numbers and again are causing significant property damage and safety concerns at the boat landing and on nearby Dominion facilities. Aerial and ground surveys by VDGIF, CCB, Dominion, and WS document consistent use of the site by 400+ black vultures and approximately 30-40 turkey vultures, though only the black vultures are causing property damage at the boat ramp and parking area. The vultures are roosting in the immediate Dutch Gap area on Dominion Stacks and buildings, on Transmission Towers on both the north and south sides of the river, and in two or more forested roosts near these structural roosts. No significant satellite roosts (i.e., roosts more than ¼ mile from Dominion/Dutch Gap complex) were detected during an early morning flight by VDGIF and CCB, nor during an early morning survey to identify birds arriving at Dutch Gap from such distant areas.
Given the short-term (18-24 months) relief provided through past harassment and lethal take projects at Dutch Gap, the cooperating agencies are working together to develop a long-term management strategy for vulture management at Dutch Gap.
The U.S. Department of Agriculture's Wildlife Services Program (WS) is the lead federal agency conducting vulture management activities at Dutch Gap. WS conducts these activities under a federal migratory bird depredation/damage permit issued by the U.S. Fish and Wildlife Service. The Virginia Department of Game and Inland Fisheries (VDGIF), the Center for Conservation Biology at The College of William and Mary (CCB), Chesterfield County, and Dominion Virginia Power (Dominion) are working cooperatively with WS to resolve the Black Vulture problem at Dutch Gap.
Beginning as early as Wednesday, November 7th, Black Vultures will be baited into a large funnel trap situated on Dominion property adjacent to the Dutch Gap boat ramp. One hundred vultures will be marked with individually numbered orange patagial (wing) tags and released. Personnel from the cooperating agencies will then monitor movements of the tagged birds through surveys and through public reports of marked birds.
Within a few weeks of releasing the marked (tagged) vultures, WS will initiate extensive afternoon/dusk and early morning harassment of the vultures utilizing Dutch Gap through use of pyrotechnics and lasers. VDGIF, CCB, Dominion, and Chesterfield County are cooperating in this effort to disperse the birds as they return to the Dutch Gap night roosts and to prevent the vultures from returning to the boat ramp and Dominion buildings each morning. The harassment effort is expected to last up to 14 days, after which the vultures hopefully will have discontinued roosting or gathering at sites of concern.
If the vultures do not disperse after this prolonged harassment, or if they resume roosting or congregating in the Dutch Gap parking lots or in other areas where their presence creates a safety or property damage hazard, harassment and/or lethal take of the nuisance birds, combined with continued monitoring of marked birds will be implemented as necessary upon further review by the project cooperators.
Monitoring and Research Efforts
As described above, 100 individuals have been tagged with orange wing markers bearing a unique three-digit code assigned to each individual, and then released. These markers are visible while the bird is perched and often are visible in flight. We encourage any wildlife enthusiasts who see these tagged vultures to report them via email to: firstname.lastname@example.org. If possible, report the date, time of day, location, activity of the bird (feeding, roosting, loafing, flying), and the tag number.
If funding is available, DGIF and CCB will conduct additional aerial surveys for night roosts after dispersal of the Dutch Gap roosts, to monitor the activities and ultimate destinations of these birds.
After the initial trapping, marking, and harassment efforts are concluded, and provided funding is forthcoming, approximately 40 additional vultures will be fitted with transmitters to facilitate remote electronic monitoring for approximately 12 months of the birds' movements, and use of night roosts and daytime loafing/feeding areas.
Black Vulture Facts
Black Vultures are large birds that have a 5-foot wingspan and weigh approximately 4-5 pounds. Their plumage is almost entirely black, except for a distinctly white outer wing patch, visible in flight. Black Vultures have a short, square tail; whitish-grey legs and feet; and an unfeathered, grey and wrinkled head. In flight, their wings are held nearly horizontal, as opposed to turkey vultures which hold their wings in a distinct, shallow "V"
Black Vultures utilize woodlands for nesting, loafing, and roosting. They forage in open areas where they visually search for carcasses. Black Vultures tend to be most abundant in flat lowlands and are less common at high elevations. Black Vultures communally roost in woodlands with tall trees, often near water. Man-made structures such as power transmission towers and cell towers are frequently used for roosting.
Range and Migration
Black Vultures breed throughout Central and South America and throughout much of the eastern United States; in recent years their range has expanded northward. They are year-long residents throughout much of this range but, during the winter months, many individuals migrate from northern portions of the species' range and from higher altitudes to more hospitable areas. Black Vultures often make short distance movements when weather patterns become unfavorable.
Black Vultures feed primarily on carrion, but they occasionally take live, relatively defenseless, prey including newborn calves or lambs. Such depredation can result in significant loss of livestock.
Breeding pairs of Black Vultures are thought to remain together throughout the year. They do not build a nest, but lay eggs directly on the ground of their nest site. Nest sites include thickets, old buildings, under trees and logs, and in rocky crevices. Typically, two eggs are laid between mid-February and early April. Eggs are incubated for 38-39 days. Young are slow-growing and do not fledge until 75-80 days of age. Age of first breeding is unknown, but is estimated to be between 5-8 years.
Adult survival rates and longevity are unknown, but adults have survived in captivity for more than 20 years. Their lifespan is estimated at 20-30 years, with low adult mortality.
The number of Black Vultures residing in Virginia is unknown. However, several rough population estimates have been derived from Christmas Bird Counts or Breeding Bird Survey data. Past estimates have ranged from 5,000 individuals upward; more recent analysis by the United States Department of Agriculture, National Wildlife Research Center, suggests that the statewide population likely is between 35,000 and 150,000+ birds. All recent studies agree that over the last 20 years, the Black Vulture population in Virginia has increased at an annual rate approaching 5-10% per year.
Virginia Department of Game and Inland Fisheries Contact: