Project Osprey Watch  
Citizen Scientists Tracking the Vineyard Ospreys

Number 4                                                                                July 2001

Contents (click to jump to):

Prodigal Father Returns
Three New Birds Tagged
The 2001 Breeding Season Begins
Check Your Predator Guards
Keep Collecting Data
Funding Acknowledged and Solicited
Web Links

            "HX," a male Osprey that nests on the Vineyard's south shore, returned home about 8:30 PM on April 14th, after a 6,800-mile round trip to Venezuela and back.

            Southern New England’s Ospreys have been studied intensively on their nesting territories, but little is known of the birds’ lives off the breeding grounds. Until recently, all that we knew of their movements when they leave their nesting areas was based on recoveries of banded birds. Usually such information is literally a dead-end trail as bands are almost always reported from dead birds.

            A band recovery reveals tantalizingly little about the bird that was found. We know where the bird was found and how long it lived, but that’s all. What route did the bird take to get to get to the point of recovery? Was this the bird’s wintering grounds or was it still migrating? How long did it take to get to where it was found and what route did it take? If the bird was on its wintering grounds, had it been there before?

            As readers of this newsletter know, in the last decade a new technology emerged that has opened a wide and fascinating window onto the lives of Ospreys away from their nests. We can now outfit an Osprey with a small, solar-powered transmitter that sends radio signals to satellites orbiting high overhead and track them wherever they travel.

            Last year, two of these 1-oz. transmitters were placed on a pair of Vineyard Ospreys, known by their band codes as "HW" and "HX," marking the beginning of a collaboration between the Felix Neck Osprey program and Mark Martell of the Minnesota Raptor Center's "Highway to the Tropics" program.

            What have we learned from the 120 birds already tagged by Martell and his colleagues? Regionally, Ospreys share similar migratory habits, broadly defined. Birds from the Pacific northwest all winter in Mexico and Central America. East coast birds all move south towards Florida, where some spend the winter, while others move on to Cuba and from there head to islands in the Caribbean or even deeper into the South American continent. Birds from Minnesota all head for South America, but take three different routes to get there.

            While these broad generalities hold, birds from a local area—and sometimes even a single family—can show very different migratory behavior. Some birds in Florida never leave the state, while others travel deep into South America every year. Members of one family of birds tagged in Minnesota took all three possible routes to South America. Our own Vineyard pair took very different paths to their wintering grounds, reminding us that once the nesting season is over, Ospreys take “separate vacations.”

            Data from our Vineyard pair also provided some fascinating insights into movement after nesting is over but before the migratory urge has taken hold of the birds. When Ospreys' parental duties are over at the nest, there is nothing holding them to the territory and they’re free to move around in search of good fishing. When our nest failed last year, the female ("HW") almost immediately left the Island and spent two months mostly around NYC before starting her migration in late September.

            The male ("HX") stayed on the Island for most of July before heading to the NYC area. There, he spent most of his time, as did the female, along the lower Hudson River, in

northern New Jersey, and around eastern Long Island Sound before moving south on Oct. 3.

            "HW" is listed as missing in action. We lost signals from her in November in Panama, where she may have died, but a spring sighting suggests she may be back with a malfunctioning transmitter.

            “HX” returned to his nest site after a very tardy departure from his wintering grounds. He didn't leave Venezuela until a week after the first Ospreys had arrived on the Vineyard in mid March!

            Whereas his southbound trip took him 34 days, he made the 3,400-mile return trip, pretty much retracing his fall route, in only 21. For much of the trip he was averaging 200 miles per day. Details of his travels can be found on the Carolina Raptor Center's webpage (http://www.birdsofprey.org) under "migration."

            These are exciting times for those of us fascinated by Ospreys. A healthy Osprey population, new technology, and generous donors enable us study one of the great marvels of nature—animal migration.

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            On June 15th Mark Martell and I flew to the Vineyard to trap Ospreys. The next day, on a cloudy, foggy morning, with the help of Gus Ben David and Chemali, his Golden Eagle, we placed satellite transmitters on the adult Ospreys at Felix Neck. The event was captured in fine photographs by Peter Simons and Julian Robinson and chronicled in great style by Vernon Laux in the Vineyard Gazette of June 22.

            This was the first time we had used a Golden Eagle (Gus's Great Horned Owl was sadly unavailable) and we weren't sure what to expect. Bald Eagles have been used in previous trapping efforts and we knew that Ospreys hate Bald Eagles with a passion perhaps even greater than their dislike for Great-horned Owls, so we suspected the Golden would work. We did warn Gus, however, that we had a can of white spray paint just in case!

            The trapping went flawlessly. The female, now known by the letters on her newly acquired color band as "KB," dove into the nets within moments of our setting up the trapping rig. Once she was safely in hand, the nets were rearranged and we set out sights on her mate, who had been nonchalantly perched on the far side of the nest, 30 paces from all the commotion of the trapping. He seemed so disinterested in the whole process that I had to go over and bang on the nest pole to get him up in the air so that he would see the eagle perched below his nest! Once on the wing, he dove into the nets in short order and we brought him in for banding and tagging.

            After both birds were banded and tagged with their transmitters and released they flew right back to their nest to contemplate their new high-tech backpacks.

            Two days later, we returned to HX's nest along the south shore and set out to trap his new mate. This took longer than we had expected because the female disappeared when we set up the nets and didn't come back for 40 minutes. When she did reappear and saw the eagle, she dove into the nets, but we were all left with an uneasy feeling that something was wrong at the nest. In fact we later learned that the nest had failed.

            On the previous Monday, a violent spring storm hit the Vineyard. HX's very late arrival meant that their chicks, if they had even hatched, must have been quite young and may have succumbed to the elements. So this pair will once again provide us with information about pre migration dispersal.

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            My annual spring migration to the Vineyard to count the Island's nesting Ospreys took place on May 11th-16th. I visited all but a couple of the 116 nesting poles and miscellaneous other structures known to support Osprey nests in recent years and can report once again that the birds are back in good numbers. This year it was a great pleasure to be accompanied on much of the survey by Paul Spitzer, a wonderful naturalist and world-renowned authority on Ospreys.

            Most of the old faithful pairs were incubating eggs while I was there.  One surprise was finding the Squibnocket pole, occupied since it was erected in 1977, bare.

            On Oyster Pond, one nest that was a housekeeping pair last year had breeding birds on eggs, while neighboring pole, active last year, had only housekeepers this spring.

            In the Scrubby Neck-Watcha Pond area, two long-used sites were vacant, while another pair has moved from a platform pole to a nearby power line. Another nearby pair of Y2K housekeepers were active breeders.

            At Mink Meadows, the long-time stronghold of Vineyard Ospreys, the nest at Rachel's Way (a failure last year) was unoccupied, while a bird (maybe from the same pair?) was incubating eggs in a nest atop a nearby chimney! And we learned that last year a housekeeping pair had built a nest in a lone pitch pine on the Mink Meadows golf course. A bit to the south, a pair built a nest on a power line at Paul's Point.

            On Edgartown Great Pond, the tree nest discovered by Julie Ben David two years ago continues to be active.

            On Chappy, two of last year's nests on Cape Pogue Bay were non-breeders, but one or two pairs seems to be housekeeping on them. Elsewhere on the island housekeepers built a nest on Caleb Pond, and a new active nest has been found on a power line off Litchfield Rd.

            Pending confirmation of a nest at the south end of Oyster Pond, our known count for 2001 is:

Breeding pairs:            63-4

Housekeepers:            2-4

            This appears to be down by a couple of pairs from last year, but I know there are more housekeepers and suspect more breeders out there somewhere. While scouting for new pairs, I encountered 5 birds circling around the Edgartown cell tower, calling, displaying, carrying sticks, and giving every indication that they thought this to be the ultimate in Osprey nest structures. Keep your eyes open and let us know if you see any new nests!

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Those of you with nests on your property should check around your poles. Sadly, we lost a nest in Edgartown, almost surely because the bushes around the pole had grown so high that a raccoon was able to climb above the predator guard and gain access to the nest. So get out the loppers and axes and protect your nest!

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I was remiss in not getting data forms out to nest watchers this year--too busy making maps and fund-raising. But rest assured that your observations on the activities of your birds are very useful indeed. I hope you're in the habit of taking notes on your birds and can send me some data at the end of the breeding season.

I will be on the Island visiting all the nests around fledging time this year, so this year it won't be as critical as some for you to count fledglings. Hope to see you soon!

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A huge "thank you" to 20 sponsors who contributed just over $30,000 for this year's transmitters. We would like to increase our sample size and tag more birds next year. If you're interested in sponsoring transmitters for "your" Ospreys, or contributing to transmitters for the Mink Meadows Ospreys (our next target pair), please contact Rob Bierregaard (phone 704 333 2405 or email: rbierreg@email.uncc.edu) for details. (Tax deductible contributions will go to the Raptor Center at the Univ. of Minnesota.)

If you would like to receive periodic updates on our birds' migration and breeding season activity, contact Rob at the email address above to be put on our e-mailing list.

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Two websites will track the Vineyard Ospreys' migration. For detailed maps along with a running play-by-play description of their movements, log on to the Carolina Raptor Center's webpage: http://www.birdsofprey.org and click on "Migration." The travels of the Vineyard birds will also be displayed on the Minnesota Raptor Center's webpage http://www.raptor.cvm.umn.edu (follow the link to the "Highway to the Tropics" page and then click on "migration data"). At this site you will be able to compare the Vineyard birds to all the other Ospreys tagged by Martell and his collaborators.

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