Wildlife researchers on Cape Cod are tagging some of the elusive shorebirds known as red knots.
The robin-size birds are on New Jersey's endangered species list and have been proposed for inclusion on the federal list.
Researchers are collecting feather samples and measuring, weighing and tagging the birds. Their legs are being fit with tiny geolocators.
Biologists hope the geolocators will use ambient light to calculate and record the locations of the birds, helping conservation workers who recapture them to determine their migration routes.
The U.S. Fish and Wildlife Service says the red knot population has dropped by up to 75 percent since the 1980s in some areas. The decrease is partly fueled by a drastic decline in the horseshoe crab population in the Delaware Bay, a key refueling stop.
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