At 4 a.m., David Kramar sat in a camouflaged blind, nestled high in an Appalachian Mountain forest. A deer carcass was in place and a rocket net was ready to be detonated.
Within a few hours, Kramar, a doctoral candidate in College of Natural Resources and Environment’s Department of Geography, planned to have a golden eagle trapped, sampled, and outfitted with a high-resolution, cellular-based GPS tracking unit. As if out of thin air, one of the estimated 2,000 golden eagles found east of the Mississippi River swooped down to the carcass. As it lowered its head to eat, Kramar detonated the net, trapping the bird.
Kramar has studied eagles for many years, focusing his research on contaminants such as mercury and lead in bald eagles. His background and expertise led him to study golden eagles as a project associate with the college’s Conservation Management Institute and in collaboration with the Virginia Department of Game and Inland Fisheries (VDGIF). The research focuses on both contaminant levels found in golden eagles and their migratory patterns. The big picture is important, he said. “What is happening in the landscape that leads them to accumulate high levels of metals in their systems?”
Kramar trapped an average of two golden eagles a week from early February to mid-March 2011 in partnership with the VDGIF. “In general, our trapping success rate is between 80 and 100 percent once we have confirmed a bird on bait and made plans to trap it,” he said.
The time-consuming process begins by identifying a suitable location, placing deer carcasses at the site, and monitoring the area with a remote still camera. Once a golden eagle is observed, a fresh carcass is placed on site and a rocket net that measures 40 by 60 feet when deployed is put into position. Site set-up takes about two hours and is done at night when the eagles are roosting. Kramar, often accompanied by Jeff Cooper, an avian biologist with the VDGIF, waits in a nearby blind for an eagle to come to the bait.
When a bird arrives, Kramar lets it eat for a few minutes. “It’s important that the bird’s head is down to reduce the likelihood of escape or injury,” he said. “These are fast birds. It is not uncommon for them to move up to 12 feet from the bait after the net is launched. The closer they are to the edge of the net, the more likely they are to escape.”
Once the trapped bird is safely removed from the net, Kramar places a falconer’s hood over its head and restrains its wings with a device called an abba. He collects body measurements, as well as blood and feather samples, then fits the bird with a GPS tracking unit, and releases it.
Data gathered from the trapped birds are used by members of the Eastern Golden Eagle Working Group, a collaboration of more than 40 biologists, geographers, and wildlife managers from the United States and Canada dedicated to developing a more comprehensive understanding of golden eagles in eastern North America. For example, some members use the GPS data, including time spent foraging and flying, altitude, flight speed, and location, to investigate the birds’ migratory patterns. Others use feather samples to study the genetic differences between eastern and western populations of golden eagles.
“I look at birds as an endpoint,” Kramar said. “If I know the levels of a contaminant, I can try to explain those levels as a function of the physical environment and what humans are doing to it.” He said he hopes his findings will generate awareness for the golden eagle as a wintering species in Virginia and guide policy plans to address such issues as habitat protection. He also wants the research to be integrated into other curriculum, particularly in the context of K-12 educational outreach.
The relatively small size of the eastern population of golden eagles makes it particularly vulnerable to threats such as lead poisoning, incidental trapping, habitat loss, and turbine collision, he said. “The development of wind turbines along the linear ridges of the Appalachian Mountains may create a very real threat to these birds if their migratory and ridgeline preferences are not accounted for,” Kramar said.
A rescued golden eagle was released at Harvey’s Knob Overlook along the Blue Ridge Parkway, north of Roanoke, Va., on Feb. 16, 2011.
The eagle lost a toe after being caught in a foothold trap in Craig County, Va., and was rehabilitated by The Wildlife Center of Virginia. David Kramar worked with the Virginia Department of Game and Inland Fisheries to outfit the eagle with a cellular-based GPS tracking unit before its release.
Trapping has occurred in many different locations since the research started, but until recently, there were no trapping sites in the southern Blue Ridge Mountains.
David Kramar was referred to Virginia Tech alumnus Carl McDaniel, the hunting and outdoor activity supervisor at Primland near Meadows of Dan, Va., who reported seeing golden eagles on the grounds of the 12,000-acre resort.
“As we were driving around trying to locate potential trapping sites, I noticed a golden eagle in flight,” Kramar said.
Areas such as Primland, which offer valuable new information on the wintering range of golden eagles, are currently under-represented in the overall study.
(Photo courtesy of Primland.)
Much of the Eastern Golden Eagle Working Group’s research was presented at the 2011 Annual Meeting of the Raptor Research Foundation in Duluth, Minn., where David Kramar helped organize a special symposium on the eastern golden eagle population.
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