A satellite transmitter chronicles two years of a whimbrel’s migrations
A whimbrel named Hope, outfitted with a satellite transmitter since May 2009 to track her migrations, amazed scientists by returning for the third time in early April 2011 to a wildlife reserve at the southern Delmarva Peninsula in Virginia. Whimbrels are a species of shorebird known for their long-distance migrations. For the past two years, scientists have tracked Hope’s journeys between her breeding territory in sub-Arctic northwestern Canada and her winter home at St. Croix in the U.S. Virgin Islands.
From the time the transmitter was attached to her in May 2009 to her latest return to the southern Delmarva in early April 2011, Hope has completed two full migration loops, logging over 21,000 miles (33,000 km). It’s an astonishing feat for a bird that’s only about 17 inches (44 cm) in length and weighs between 11 and 17 ounces (310 to 493 grams).
Previous studies have shown that the lower Delmarva Peninsula is a critical staging area for migrating whimbrels. During their stay over several weeks, the birds feed voraciously, mostly on fiddler crabs that are abundant in the barrier island lagoon system, to build up fat reserves that will fuel their flight to their nesting grounds.
Scientists at the College of William and Mary-Virginia Commonwealth University and the Nature Conservancy of Virginia have been studying the migratory journeys of whimbrels using lightweight satellite transmitters that are attached to the birds with a special Teflon harness. They were very excited when Hope returned to the same creek at the Conservancy’s Virginia Coast Reserve for the third consecutive spring on April 8, 2011. She arrived there after a 75-hour flight over the Atlantic Ocean from her winter home in St. Croix, U.S. Virgin Islands, 1,850 miles (2,900 km) away. Sometime in May, having fattened up on fiddler crabs, she will depart to her breeding territory near where the MacKenzie River meets the Beaufort Sea in sub-Arctic northwestern Canada.
Whimbrels, also known by their taxonomic name Numenius phaeopus, are found worldwide. They breed during the summer in the sub-Arctic regions of North America, Europe, and Asia, then disperse to wintering grounds in southern North America, South America, Africa, south Asia, and Australia. The whimbrel population in North and South America is a sub-species called Numenius phaeopus hudsonicus. They breed in sub-Arctic Canada and Alaska, and winter along the east and west coasts of southern North America and South America.
The long-distance journeys of migratory bird species connect distant lands thousands of miles apart; each location is critical to the survival of the species. Therefore, conserving a migratory species requires international cooperation to preserve their habitats in different countries. In the past few decades, there have been steep declines in many migratory bird species, including whimbrels. There is an urgent need to identify the locations of the birds’ breeding, wintering, and staging areas in different countries so that, with the cooperation of their respective governments, those locations can be designated as wildlife preserves. The data provided by Hope, and several other whimbrels with satellite transmitters, will help scientists determine those sites critical to the survival of whimbrels in the Americas.
The first year of tracking Hope’s migration began on May 19, 2009. She was trapped and outfitted with a solar-powered satellite transmitter weighing just 9.5 grams. Scientists followed her journey with amazement: she left Virginia on May 26th, 2009, for the western shore of James Bay, Canada. After spending three weeks there, she headed to where the MacKenzie River, in northwest Canada, empties into the Beaufort Sea, where she stayed for over two weeks. Hope then flew to South Hampton Island in the upper Hudson Bay. After spending about three weeks there, she flew non-stop for more than 3,500 miles (5,630 km), most of it over the Atlantic Ocean, to St. Croix for the winter. During that single migration loop, Hope traveled over 14,170 miles (22,800 km).
The following year, she repeated that journey, following similar migratory routes. It included a trip back to the same marsh where she had been captured and fitted with the transmitter in the previous year. And again, she began a similar journey for 2011 when she departed from St. Croix on about April 5, 2011, arriving at her creek in the lower Delmarva Peninsula 75 hours later.
The whimbrel satellite tracking program, conducted by the Center for Conservation Biology at the College of William and Mary, and the Virginia Chapter of the Nature Conservancy, is helping scientists identify important whimbrel migration locations – their breeding grounds, winter homes, and staging areas – that are critical to their survival. A whimbrel named Hope is continuing to reveal the story of her migrations spanning the North American continent. She returned in early April 2011 for the third consecutive spring to the lower Delmarva Peninsula of Virginia, an important staging area for whimbrels where they spend a few weeks gorging on fiddler crabs to accumulate fat reserves needed to power the next leg of their migratory journey. Hope will leave sometime in May 2011 for her coastal breeding territory near the MacKenzie river in sub-Arctic northwest Canada. Along the way, she will be tracked by scientists working hard to help save her species.