Wild Side : Wildlife biologists tag willets to learn their habits
Photo by Matt Pelikan
Perhaps 75 yards away, Luanne Johnson of BiodiversityWorks and Joe Smith, an ornithologist from New Jersey, sheer off from a loose sand jeep trail and start up the slope of the back dunes along East Beach, Chappaquiddick. Moving carefully through dune grass, roses, and poison ivy, Luanne and Joe gradually separate. Each holds a pole of bamboo, and between the poles a fine net unfurls.
Bracketing a clump of shrub they had flagged the evening before, they lay the net down. I can't follow what happens next, but moments later, Joe turns toward where I'm standing, holding up what looks like a green sock. As he approaches, I can see the legs and tail of a shorebird projecting from the open end of the sock. It's the landing gear of a female willet, just plucked off an active nest as part of a study of this unusual shorebird.
About the size of lanky bantam hens, willets nest on the margins of salt marshes. They are drab birds except in flight, when their wings display startling white-and-black stripes. Like many shorebirds, willets were gunned almost into oblivion before the passage, in the 20th century, of laws to protect migratory birds. The boldness of this species in defense of its nest, so useful for Mr. Smith's research, surely also made willets easy targets.
As their numbers have rebounded, like their charismatic relative, the oystercatcher, willets have re-colonized much of their former breeding range along the East Coast. Now nesting as far north as Nova Scotia, willets resumed breeding in modest numbers on the Vineyard about decade ago. Perhaps a dozen pairs now inhabit the Island, Ms. Johnson estimates.
The species has been studied only sparingly, though, and little is known about where willets winter, how they migrate, and how our coastal population is related to a second population, larger and paler than our birds, that nests on the northern plains in interior North America. A local foundation, endowed by the estate of the late Island birder Gus Daniels, provided funding to BiodiversityWorks for a study of Vineyard willets.
BiodversityWorks, a local nonprofit specializing in wildlife research, enlisted the aid of Mr. Smith, a veteran field biologist who has studied willets extensively farther south on the East Coast. The Trustees of Reservations and Sheriff's Meadow Foundation also assisted the project.
The method used to capture the bird on Chappaquiddick depends on a behavioral quirk of the willet: incubating birds often "sit tight," protecting their eggs and relying on concealment rather than flight for safety. Returning to the staging area with the bird in its green sock, Joe, Luanne, and Liz Baldwin, also of BiodiversityWorks, unpack an extensive tool kit and get to work. With special pliers, Joe clamps a corrosion-resistant band on one leg of the bird, and a unique number the band bears is recorded, so the bird can always be identified. A second colored band will help make this bird recognizable when seen at a distance. Measurements are taken of body weight and wing, leg, and beak length. A tip of a feather is snipped off, destined to provide a sample of the bird's DNA for a related study comparing the genetic composition of the two willet populations.
Joe holds the bird loosely but securely, working efficiently but without hurry. The bird, for its part, is surely not happy, but, surprisingly, it doesn't struggle. Through most of the procedure, its legs are relaxed and flexible. As the last step in the process, the willet gets a final adornment: a tiny green data logger, about the size of a lima bean, affixed to one of its legs.
Lighter, less complex, and less expensive than the satellite-tracking transmitters that have been used to study Vineyard ospreys, the tiny device does nothing more than keep time and record the intensity of light. It isn't much to go on, but analysis of the data will yield the sunrise and sunset times wherever the bird happens to go. Mr. Smith reports that those figures will suffice to reconstruct the location of the bird down to about 60 miles — not enough to show daily activity, but sufficient to indicate where the bird winters, how it gets there, and how long it stays.
Actually obtaining the data will depend on another behavioral oddity of the willet: these birds, which are long-lived, usually return each summer to the same nesting territory. A year from now, Mr. Smith hopes to recapture the same bird, probably in the same way, making it possible to download a year's data from the device. Combined with results from similar operations, this bird's activity over the coming year will help biologists understand what resources are necessary for this resilient species to continue its recovery.
Today's data collection being completed, Luanne carries the bird a few feet away from our group, carefully peels off the sock, and lets it go. She flies briskly out over the marsh, joins another willet (probably her mate), and begins to preen. Based on what is known so far of these birds, she will probably have completed a roundtrip to northeastern South America before her appointment next June with Mr. Smith.