The rufa subspecies of Red Knot, which may soon be listed as threatened under the Endangered Species Act, is famous for its epic annual journey between southern Argentina and the arctic.
Not all rufa knots make the 16,500-mile round trip, however; many birds winter along the coasts of Florida, Georgia, and South Carolina and on the Texas coast. Scientists are unraveling their migratory secrets with the use of light-level geolocators.
As we noted in our June 2012 issue (“On the Move,” page 46), the tracking devices revealed that birds caught in Massachusetts in fall 2009 had wintered along the Atlantic coast, in Cuba and Haiti, and on the northern coast of South America.
Now, from a paper published this summer in the Wader Study Group Bulletin, we learn that Red Knots in Texas spend more than three-fourths of each year — from late July or early August to mid-May — from Matagorda Island, on the state’s mid-coast, south to the state of Tamaulipas in Mexico. Although knots had been recorded in Texas in past winters, the finding was still surprising because no one knew if the birds stuck around or flew farther south later in the season.
In spring, the knots migrated north through the central states and provinces and followed the same path south in mid-summer. Along the way, they stopped to refuel on the Nelson River delta along the southwestern shore of Hudson Bay and on the south shore of James Bay. They remained at the sites for about 11 days before making a direct flight to the Gulf coast in two to three days.
The study was led by David Newstead of the Corpus Christi-based non-profit Coastal Bend Bays and Estuaries Program.
A version of this article appeared in the December 2013 issue of BirdWatching.