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Migratory birds rely on Georgia's islands

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POSTED: November 20, 2007 5:00 a.m.
BRUNSWICK — Red knots are one of the most watched-for shorebirds on the Georgia coast in fall, a rare, long-distance aviator whose presence highlights the critical need to conserve coastal habitats.
Georgia shores are host to two different red knot populations throughout the year, one that migrates from Canada all the way to southern South America and another that winters in the Southeastern U.S.
The South American wintering group is seen in Georgia primarily in late spring as these marathon flyers feed on horseshoe crab eggs here and in other Atlantic coast states on their 11,000 mile flight north again to breed.  The Southeastern U.S. wintering group begins arriving in Georgia from their Arctic breeding grounds in late July. They gather in th Altamaha River Delta, probing sandbars at low tide for small clams they swallow whole, gobbling up to three per minute.
Juveniles left behind on the tundra to migrate with other young red knots show up in September. Adults molt, trading russet-tinged breast plumage and worn wing feathers for drab-gray winter plumage. Then flocks begin dispersing in October.
Some knots stay in Georgia and South Carolina all winter, depending on what foods are available. The rest of this Southeastern flock head across land for Florida’s lower Gulf Coast.
Fall and winter red knot concentrations in Georgia are tied primarily to the abundance and distribution of the favored clam species, the dwarf surf clam and coquinas, said Brad Winn of the state Department of Natural Resources’ Wildlife Resources Division.
“The size of the aggregations, their location and how long they stay in one place is very food-resource based,” said Winn, coastal program manager for the division’s Nongame Conservation Section. The small clams are themselves dependent on good, clean estuarine and marine waters.
In spring, local knots shift north into the Carolinas in late April and early May, continuing to feed on clams before leaving for the Artic again at the end of May.  Georgia’s late-spring concentrations of knots are from a different flock, the long-distance migrators moving up from southern South America.   These birds are focused on horseshoe crab eggs abundant where the crabs spawn along the Georgia coast.
Flocks estimated at up to 12,000 red knots have been seen here when dwarf surf clams are abundant. But fall knot numbers have been much lower the last three years, coinciding with the lower availability of clams.
Red knot populations, like those of many other shorebirds, are declining. A U.S. Fish & Wildlife Service report released in July marked a drastic decrease in the subspecies that migrates through Georgia.
Studies show that the subspecies might be extinct within a decade if adult survival rates remain as low as those assessed from 1994 through 2002, according to the report. One factor cited is an increasing scarcity of horseshoe crab eggs in Delaware Bay, where commercial harvesting of crabs for bait has undercut a critical food source for red knots.
The Nongame Conservation Section works to protect the state’s diverse wildlife and natural habitats, following a Wildlife Action Plan that outlines conservation goals and measures involving shorebirds and hundreds of other species.
Georgians can help by donating through the “Give Wildlife a Chance” State Income Tax Checkoff and buying bald eagle or hummingbird license plates. The wildlife tags are available for a one-time $25 fee at county tag offices, via mail-in forms or online at http://mvd.dor.ga .gov/tags

Red knots at a glance
This sandpiper family member is known for its cinnamon-colored breeding plumage and appetite for small clams, which it swallows whole. Some red knots in the Western Hemisphere migrate 11,000 miles, flying from the Arctic to southern Chile and Argentina in fall, and back again in spring.
Adult knots leave their young before they fledge. Juveniles migrate at least part of the way without the older birds.
The species is in decline, likely in part because of fewer horseshoe crab eggs, a key food source, at spring staging areas such as Delaware Bay. Commercial fisheries increased their harvest of horseshoe crabs for bait in the 1990s.
Many red knots have been banded with leg “flag” bands. The colors denote the country in which the bird was banded, such as red for Chile and green for the U.S.
One story behind the knot’s name is that it comes from the Canute the Great, a king of England, Denmark and Norway who, legend says, once tried to hold back the tide.
Online: U.S. Fish & Wildlife Service, http://www.fws.gov/northeast/redknot/
Western Hemisphere Shorebird Reserve Network, http://www.whsrn.org/news/whsrnews.html#red-knot

Sources: U.S. Fish & Wildlife Service; Georgia DNR
 

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