Looking north on Brigantine Natural Area. 
Looking south from Brigantine Natural Area, NJ.Most of the shorebirds are semipalmated sandpipers and semipalmated plovers with some knot ( in the foreground) and sanderling.Encouraged by the reports of shorebirds at Stone Harbor, I drove out to North Brigantine Natural Area, NJ, one of the most important southbound migratory shorebird stopovers on the east coast. This Natural Area is oddly placed, just north of Atlantic City (the casino skyline can be seen from the Natural Area) and smack in the middle of the most densely populated shoreline in the country. Exhausted by the long flight from Arctic breeding areas, shorebirds home-in on this fine habitat like bees to honey (seniors to the casinos?). They feed on the abundant donax clams that filter food in the swash zone of the Atlantic beach. The clams are widespread, but dense crowds of people make most ocean coast habitats unavailable to shorebirds. The greenheads and the lack of access at the northern end of the natural area helps keep the number of people lower.
Among the nearly 5,000 shorebirds on the beach I found a few old friends. A red knot with Flag lime (YAX) was one we captured in Hog Island, VA, in 2006. Another knot with Flag lime (1NE) we caught at Moore’s Beach, NJ, in 2009. In all, I found 10 birds with unique, alpha-numeric leg flags, more than 10% of the 95 knots on the beach. Five had orange leg flags indicating they were banded in Argentina.
Red knot with unique alpha-numeric, lime green leg flag.
This is the beauty of our system for identifying individual shorebirds with leg flags. It was clear I was seeing the vanguard of knots coming back south from Arctic breeding areas. The first wave of migrants are usually females who leave the Arctic first; the five Argentine flags confirm that some or all of this group of 95 knots may be going the long distance to South American wintering areas. They will be followed soon by the adult males, then first-year birds or “juveniles” — those just hatched and fledged in the Arctic in June and July. Then the gates open up; both long- and short-distance birds — those wintering in SE US and the Carribean — come through Brigantine and the other important east coast stopovers like Stone Harbor, NJ and Monomoy Refuge, MA. Numbers will peak in late August and early September. Numbers of birds will remain high, however, because many of the short-distance migrants stay at Brigantine, Stone Harbor and Monomoy to molt their flight feathers. Molt typically takes at least two months and is usually complete by mid-November. The fact that individuals use these areas for long periods indicates these sites are immensely important migratory stopovers. Our work on red knots outfitted with data loggers shows that long-distance birds also rely on southbound stopovers like Brigantine and Monomoy Refuge to pack on weight so that they can make trans-ocean flights to South America. Before this work, we thought red knots only made trans-ocean flights during spring (northbound) migration. This punctuates the importance of southbound stopovers for long-distance migrants.
One can find the original banding location of all but Argentine knots at www.bandedbirds.org, a web site devoted to helping researchers and the public identify birds banded with unique leg flags and color bands. In partnership with Defenders of Wildlife, Bandedbirds.org has recently published a call for responsible people to help identify shorebirds with leg flags and will soon publish a guide to observing shorebirds without causing a disturbance.
Red knots flying above Semipalmated Sandpipers, Sempalmated Plovers and a sanderling. The left-most flying red knot shows her worn and intact flight feathers. In a few months she will have molted these feather replacing them with a new set. Also note the right-most flying knot has an orange leg flag.
