Tracking the Majestic Osprey
By E. VERNON LAUX
Gus Ben David, director of Massachusetts Audubon's Felix Neck Wildlife Sanctuary in Edgartown, takes a four-wheel-drive vehicle out into the field by the osprey pole that is visible from the entrance road to the sanctuary. Accompanying Mr. Ben David, in the passenger seat, is longtime cohort Tim Baird of Edgartown, an Island electrician. They are transporting Mr. Ben David's' 20-year-old golden eagle, named Chameli, in the back of the vehicle. The eagle acts as the lure in what is about to transpire.
These naturalists are part of an exciting research project involving state-of-the-art, solar-powered satellite transmitters combined with ancient field techniques learned from centuries of falconers, to track the Island's nesting ospreys on their migrations to wintering grounds in the tropics. Today's task is to capture and band the sanctuary's resident pair of ospreys and to fit them with their satellite harnesses.
Mark Martell, conservation coordinator of the Raptor Center at the University of Minnesota College of Veterinary Medicine, is the man in charge. He has more experience with satellite tagging birds of prey than anyone, anywhere. A more competent and personable individual, handling the people, the birds and attaching the transmitters, is impossible to imagine.
Rob Bierregard, assistant professor of biology at the University of North Carolina at Charlotte, is also instrumental in this Vineyard effort. Mr. Bierregard has long Vineyard ties, and studied raptors intensively on the Island from 1969 to 1973. He banded his first ospreys by climbing the Mink Meadows pole in 1969 and banding the young. There were two nesting pairs of ospreys on the Vineyard in 1969, and those were the first to nest on a pole.
Back in the field adjacent to the osprey pole, Mr. Ben David and Mr. Baird reach the agreed-upon location and quickly bring the golden eagle out of the back of the vehicle. They fasten her to a tether. She is anchored to the ground by her legs on a 10-foot leash. On both sides of the tether are mist nets. They are fine, but strong nylon nets used to capture birds, strung between two poles and extending 10 feet in the air.
The pair retreat to the vehicle and beat a hasty retreat out of the field to the edge of the road. The female osprey, which had been sitting on her nest pole, reacts instantly to the presence of the intruding golden eagle in her field. Instinctively, she rushes off the pole to attack the intruder, defending her nest and nestlings.
She climbs off the pole then dives in a powerful stoop, after the offending eagle. She gets within inches of the net and pulls up, apparently spotting trouble. Screaming, mad, incensed at the eagle's presence so near her young and nest site, she climbs and prepares for another stoop. She performs an acrobatic aerial maneuver, a wing-over, dives and rapidly gains speed in a renewed attack on the eagle.
Again, she pulls up just inches in front of the nearly invisible mist nets. Finally, indignant, crazed at the eagle's presence, she dives into the mist net and is caught.
Out from the bushes come Mr. Martell and Mr. Bierregard, sprinting. Mr. Ben David and Mr. Baird are not far behind as all converge on their respective birds. The researchers quickly remove the osprey from the net while Gus calms the eagle and readies her for the next round.
The female is quickly taken from the field to an opening in the trees for processing. The first thing that Mr. Martell does is gently attach a leather hood, a sort of skull cap, that covers the bird's head and eyes. This has an instant calming effect on the captured bird. This is an ancient technique, developed and used by falconers for centuries. It is still the best method for calming sharp-eyed raptors when one is handling or transporting them.
The next step in processing involves putting on a couple of bands for identification and fitting her with a specially designed harness that holds the satellite transmitter. It weighs 30 grams, is powered by a photovoltaic array and has an antenna sticking out a few inches. It is called a PTT, short for platform telemetry transmitter, and is manufactured by a company in Maryland specifically for this project.
The weight of the transmitter is only slightly more than an ounce. Ospreys, on average (the females are considerably bigger than the males), weigh more than three and a half pounds. They routinely catch fish weighing from two to three pounds; the transmitter's additional weight has no effect on them.
Banding happens quickly as the U.S. Fish and Wildlife Service band is fastened, and then an additional band with specific large letters is put on the other leg allowing specific identification by visual inspection. These are called color bands, and the ones fitted on the female and male at Felix Neck are KB and KC, respectively. These identifiers will stay with the birds and be used to identify them or talk about them.
The harness attachment has to be perfect and takes from 20 to 40 minutes to fit properly. It is critical for the bird's well being that it be just so - snug but not too tight. Mr. Martell handles this chore. He has fitted around 140 ospreys with these, and some transmitters attached in 1999 are still operational. The harness is made of Teflon and the straps are carefully sewn together over the bird's upper breast. It does not interfere with any movement or the bird's ability to perform any function.
Meanwhile, the action continues at the adjacent field where the male osprey is sitting on the nest pole. He hesitates on the pole, then can't help himself, stooping on the offending eagle and tangling in the net on the first pass. Mr. Bierregard quickly removes the much smaller male from the net and delivers him to be banded and fitted with his transmitter. The nesting pair at Felix Neck becomes the second pair to be captured and banded on the Vineyard to date.
Both birds are banded, fitted with their own harness and transmitter, and a small blood sample is taken for further DNA research before they are released. Both birds immediately return to the nest and young, shaking their heads as if to shake away the nightmare of the morning they've had. Both are now providing invaluable information that will enable hard data to be acquired on this favorite Vineyard species.
A dozen individuals were present for this event, which took place on the morning of Thursday, June 14. Some were there to help with nets, hold birds or assist with anything that was needed such as Anne Carmichael Lemenager, Rick Bayley, Michael Straight and Richard Whelan. Others were lucky enough to be taking pictures or reporting the story. "It was the most exciting and fulfilling experience that I have had since I began photographing wildlife," said Julian Robinson of Oak Bluffs, a retired college administrator and wildlife photographer.
Mr. Martell and Mr. Bierregard trapped a pair of ospreys on the south shore of West Tisbury last year and fitted them with harness and transmitter. The transmitters operate for 10 hours, then shut down for 21 hours, repeating this cycle as long as they remain operational. They relay information to satellites in polar orbits so readings are easier to obtain at the higher latitudes.
During its fall migration, the Vineyard's banded female made her way down the East Coast, across to Cuba and then flew to the west coast of Panama. She was the first conclusively documented osprey from the eastern seaboard to be known to winter on the Pacific coast of Central America. Unfortunately, her signal went cold and it is unknown whether she was killed, if the transmitter fell off or exactly what happened. She may still alive with a malfunctioning transmitter or without the transmitter, and the search for her by seeing her bands continues. There was a report in April of a bird with an antenna from the Vineyard's south shore, but follow-up attempts at confirmation have been fruitless. At this point she is missing in action.
The male flew 3,400 miles south in 34 days. It went down the East Coast, island-hopped across the Caribbean and ended up wintering along the Orinoco River in Venezuela. He departed in late March from Venezuela and hustled back to the Vineyard, where he quickly procured a new mate.
The new mate was captured and fitted with a satellite transmitter on June 16 from a nest pole along the south shore in West Tisbury. Again, Mr. Ben David and Chameli were along to entice the female to attack and be captured in a mist net. Her partner is the male that was fitted last year and whose identifier is HX. She has the identifier KD and replaces HW, the female that is still missing. So there are now four Vineyard birds to follow through the marvels of satellites and the world-wide web.
For more detailed information and maps, there is a web site that enables one to follow an individual birds movements. Set your browser to http//www.birdsofprey.org and then click on migration. Another site for Vineyard birds is raptor.cum.umn.edu.
For both teachers and students, a wealth of information and knowledge can be gained from working with satellite transmitting birds. Much can be learned about conservation, migration, geography, social studies, languages and meteorology, to name a few areas of interest. Follow the birds and see what countries they visit. It is a remarkable opportunity to learn about a wide range of topics.
What weather do the birds travel farthest in? What happens if a hurricane is approaching? What is the survival rate of young birds in their first southbound migration? The list of questions stretches to the horizon - the more we know, the more questions can be asked.
Ideally, Mr. Martell and Mr. Bierregard would like to have transmitters on six males, six females and four to six young birds. This would allow for a detailed study of the Vineyard population, which currently stands at about 150 birds, including 62 active nests. Ospreys don't breed until they are three or four years old and average about 12 to 14 years old. Mortality is high on young birds and the hazards of growing up severe for birds under the age of four years.
The transmitters and monitoring costs are now at about $15,000 per bird. Funds are always in short supply and it has been through the generosity and interest of a few donors that most of this work has been conducted. This important and valuable research needs support; if you are able to help, e-mail Mark Martell at email@example.com or phone, 612-624-9790 at The Raptor Center at the University of Minnesota College of Veterinary Medicine to find out how to make a tax-deductible contribution directly to this research being conducted on Vineyard birds.