By David Pendered
Georgia is joining an effort to track the migratory patterns of a bird that biologists predict could be extinct within 15 years – the tiny saltwater sparrow, which is barely more than 4 inches long and weighs less than an ounce.
A report released in January in the journal Conservation Biology paints a bleak picture for the fate of the little critter:
- “Based on our findings, we predict a collapse of the global population of Saltmarsh Sparrows (A. caudacutus) within the next 50 years and suggest that immediate conservation action is needed to prevent extinction of this species. We also suggest mitigation actions to restore sediment supply to coastal marshes to help sustain this ecosystem into the future.”
Coastal marshes have been heavily used by humans for centuries, according to the report. Man sought food from the critters who live in the marsh, built road crossings and dug ditches to drain marsh to create farmland.
Now, further stress is appearing in the form of rising sea levels. The higher waters are flooding areas where birds nest, according to the report:
- “Finally, sea-level rise is changing the sediment supply, water salinity, and total area of coastal wetlands globally…. These effects are similar to the consequences of local human impacts on tidal marshes but play out over centurial time scales.”
Tim Keyes, a wildlife biologist with the Georgia Department of Natural Resources put it this way: “Their nest numbers are dropping and habitat is being lost. Marsh migration is not occurring at a rate to replace habitat loss.”
The number of saltmarsh sparrows has plummeted from an estimated 250,000 in the year 2000 to 53,000 today, according to a DNR statement.
In 2015, Georgia added the saltmarsh sparrow to its list of high priority species, as outlined in the 10-year State Wildlife Action Plan. The federal government approved the plan in 2016.
In the case of the saltmarsh sparrow, inclusion on the list of “high priority species” means that the state has determined the bird is a member of a “critically imperiled species.”
In response, Georgia has joined an effort to track the birds as they migrate from their winter nests along Georgia’s coast to breeding grounds located along the coastline from Virginia to Maine.
The work started in March.
Mini transmitters were attached to 25 saltwater sparrows near the Jekyll Island causeway and on a marsh island off Little Cumberland Island. Keyes and Adam Smith, of the U.S. Fish and Wildlife Service, led volunteers in netting and attaching the so-called “nano-tags.”
Signals sent by transmitters are tracked by antennas that have been raised at Brunswick and on Ossabaw Island. A third is planned for St. Simons Island. The work is being funded by a grant from the National Fish and Wildlife Foundation.
Each antenna can track a bird that passes within about 15 miles of the antenna and sightings are entered into a national database. As of June 1, the towers have tracked 11 of the 25 saltwater sparrows tagged in Georgia. A network of antennas erected northward along the coastline is to track the birds as they migrate to breeding grounds. Transmitter batteries last up to 80 days.
One goal of the program is to identify where birds from Georgia stop to rest and eat during their trip north. Smith said similar tracking programs have shown the importance of a single stopover in the overall success of a seasonal migration.
“This effect may be even more prominent with a habitat specialist like the saltmarsh sparrow,” he said. “Thus, knowing where these birds are stopping to rest and refuel during migration, and how quickly they move after those stops, is crucial information to managers as the sparrows’ habitat continues to shrink.”