National Wildlife Research Center (NWRC) |
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Resource Protection Through Avian Population Management
PROJECT GOALS:
Project Accomplishments 2007 Diazacon Used To Reduce Monk Parakeet Reproduction—The monk parakeet, which is native to South America, constructs its nest of sticks and branches and maintains it throughout the year. Unfortunately, parakeets often build their bulky nests in electrical substations and other utility structures. In close proximity to energized equipment, nest material or the birds can create short circuits and produce power outages. This problem has been troublesome for electric utility companies in Florida and other parts of the United States for more than 20 years. To help address this problem, NWRC biologists are investigating ways to slow the growth of the monk parakeet population. Reproductive control using the chemical diazacon, a cholinesterase-inhibiting compound, is one approach that shows promise. In collaboration with a south Florida utility company, NWRC biologists established bait stations at several electrical substations where monk parakeets were nesting. At some sites, the bait stations contained diazacon-treated sunflower seeds; at other sites, no treated bait was offered. The treated bait was presented for 10 days, and visits to the bait stations by parakeets were documented with motion-activated digital cameras. Then, 7–8 weeks later, nests at treated and untreated substations were removed, and the numbers of eggs and nestlings were recorded. Nest examinations revealed that average productivity at the treated sites was 0.65 nestlings/nest, compared to 3.07 nestlings/nest at untreated sites. These numbers indicate a 79% reduction due to the treatment and are consistent with results obtained in 2006. Vulture Movements Tracked by Satellite—Black vultures and turkey vultures represent serious safety hazards for high-speed, low-flying military aircraft. Winter surveys indicate that vulture numbers in South Carolina are two to three times higher than national averages. In recognition of the potential danger to its pilots and aircraft, the U.S. Navy contracted with Wildlife Services (WS) to investigate options for vulture management at the Marine Corps Air Station in Beaufort, SC. The goal of the study is to document vulture movements and activity in the area of the air base, and devise a management plan to alleviate potential hazards. Working with wildlife biologists from the South Carolina WS office, NWRC researchers attached solar-powered GPS satellite transmitters to eight black vultures and eight turkey vultures. Hourly readings provided data on each vulture’s location, altitude, and speed. The GPS locations were processed into a GIS database that permits analyses of daily and seasonal movements, night communal roost locations, and daytime activity centers. In addition to the 16 birds with transmitters, WS biologists also marked more than 120 vultures with conspicuous, white wing tags. Resightings of these birds within the study area provided important supplementary information on vulture movements and resource use. As of October 2007, the longest movement by a “transmittered” bird was approximately 500 miles, from Beaufort, SC, to Homestead, FL. Most of the birds with transmitters have remained within 10 miles of Beaufort. An unexpected benefit of the study was the collection of new information on daily vulture activity. Data showed that the majority of vulture activity occurs later in the day, whereas bird surveys are usually conducted within four hours of sunrise. Thus, most black vultures are not detected during these surveys; consequently, vulture population sizes may be underestimated. These findings are being incorporated into revised protocols for estimating the size of vulture populations. Project
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Last Modified: March 6, 2008