WASHINGTON – It sounds like an operation worthy of the Department of Homeland Security.
State officials are keeping close tabs on the movements of a group of destructive foreigners, enlisting the help of the public and employing satellites, radio tracking and regular surveillance to map their behavior and whereabouts in relation to potential domestic targets.
The suspects — mute swans. The targets — underwater grasses in the Chesapeake Bay.
The Maryland Department of Natural Resources is eager to find out more about the swans, an invasive species that state biologists say is overgrazing grasses and damaging other wildlife in the bay. An earlier state plan to shoot hundreds of the birds as part of a long-term plan to reduce the population was stopped by the federal government, after environmentalists challenged the plans in court.
Now, the department is working with a Cornell University wildlife biology graduate student who is tracking seasonal movements and behavior of flocks of mute swans and breeding swans around the bay.
Christine Sousa plans to compare the movements of the birds with locations of underwater grass beds. She is also observing mute swan behavior and interaction with other native wildlife.
About 85 swans are sporting white neck collars with black letters and numbers printed on them. Four birds wear the coded collars plus small black backpack harnesses with satellite transmitters, and 37 wear white collars with small radio transmitters.
Sousa’s project, which began in the spring, happens to overlap with the aims of state wildlife officials, who identified several areas of research when they developed their mute swan management plan, said Larry Hindman, Waterfowl Project Leader for the Department of Natural Resources.
Wildlife management officials said that the research Sousa is conducting will help improve their understanding of the swan.
“If we’re comfortable that a very thorough job was done,” the study’s results will be published in a peer-reviewed journal and incorporated into the state’s management plan, Hindman said.
Sousa and two state biologists collared the birds this spring and summer in Talbot, Queen Anne’s and Dorchester counties, which the department says have the largest numbers of mute swans in the state.
Since the birds were collared, Sousa has been commuting to the Eastern Shore from upstate New York almost weekly to monitor the movement of the birds. She goes to locations where she previously saw birds and tracks the radio transmitters with an antenna and receiver that beeps loudly when they are near.
When Sousa spots a bird, she records the location on county maps — information that she later plugs into software that plots the birds’ movements.
While the study is still months away from completion, Sousa notes that underwater sea grasses and the way people feed the swans seem to be affecting their movements.
“The state assumed, based on previous studies that . . . the birds would hold their territories year-round, and we’re finding that they don’t necessarily do that,” Sousa said.
She estimates about 80 to 90 percent of the “fairly domestic” population she monitors are at some point being fed by people, which has helped the birds thrive in the region.
The birds have exhibited aggressive behavior toward other waterfowl, particularly the tundra swan, Sousa noted in a progress report this fall.
To get a more accurate assessment of the birds’ movements, Sousa and DNR officials have asked the public to help by reporting sightings of collared birds online, at http://dnrweb.dnr.state.md.us/dnrasp/websurvey/wildlife/msnsform.asp.
“A lot of people watch the birds . . . and we thought that it might be something they might be interested in doing,” Sousa said.
Hindman notes that people will probably need the help of spotting codes or binoculars to read the exact codes on the collars.