In the late 1800s, sport and commercial hunters shot down 4,000 red knots a month along what is now The Nature Conservancy?s Virginia Coast Reserve.

The population of these medium-sized sandpipers rebounded, largely due to the bird protection movement that grew over the past century. But recently, their numbers have begun to plummet again, and scientists are racing against the clock to understand why.

To learn more, researchers from the Conservancy, Virginia Tech and William and Mary?s Center for Conservation Biology have launched the Virginia Red Knot Stopover Project. The project is part of an international research effort stretching from Argentina to the Arctic.

A Good Place for a Meal

The Conservancy's Virginia Coast Reserve is a key stopover site for migratory red knots, offering protected natural habitat and food to fuel the next leg of their journey from winter grounds in places like Brazil and Tierra del Fuego to the Arctic where they breed.

Scientists initially thought that all red knots stop over in Delaware Bay and perhaps find insufficient prey, causing the population to decline. But Jim Fraser and colleagues from Virginia Tech discovered a different story from radio-tagged birds in Virginia. ?It looks as though the birds stopping in Virginia fatten up here and go straight to the Arctic,? Fraser says.
   
?More red knots stopped over in Virginia this spring than any other state,? says Barry Truitt, the Conservancy's chief scientist at the Virginia Coast Reserve. ?Our reserve has the only naturally functioning system of barrier islands on the East Coast. This system?s diverse habitats are globally important for shorebirds.?

And that includes red knots. The entire population stops along the mid-Atlantic coast to build up stores of fat for the journey north, and at the reserve they double their weight by feeding on abundant coquina clams, blue mussel spat and other invertebrates.

So the question is ? with such an abundance of food available, why are fewer red knots showing up every year?

All Signs Point North

Truitt and Brian Watts from the Center for Conservation Biology (CCB) have conducted meticulous weekly aerial surveys since the mid-1990s, when numbers topped out at 9,000 red knots. In 2007 the count dropped to 7,000 on peak days.

This past spring, CCB crews conducted re-sightings of red knots on island beaches. By identifying and tracking birds sporting leg flags and bands, they can map them over time and analyze foraging habits, including how long individual birds feed in the area. All of this data will provide valuable clues about the decline.
   
With mounting scientific evidence revealing that red knots easily refuel on the bounty at the Virginia Coast Reserve, scientists are beginning to explore what happens to these long-distance flyers where they nest.
 
Little is known about the red knot?s breeding habits. Truitt?s first trip to the Arctic in 2000 with research partners from New Jersey turned up just 13 nesting pairs. But in coming seasons, Virginia Tech scientists expect solar-powered satellite transmitters to fill in key data.

?Severe weather extremes like late snows and heavy rains could affect these birds up there, and now we are seeing the effects of climate change,? says Truitt. ?I think the answer is in the Arctic.?

Nature picture credits (top to bottom, left to right): Photo © Barry Truitt/TNC (Red knot flock); Photo © Barry Truitt/TNC (Red knot with satellite transmitter); Photo © Hal Brindley.com (Virginia Coast Reserve).