text: FITCHBURG -- Only one swan still floats in Mirror Lake, but getting more of these iconic birds may prove to be a challenge.
  Following the death of Coggshall Park's only other swan on Oct. 6 -- and amid an outpouring of grief among residents on social media -- city officials submitted a permit to the MassWildlife to bring at least one more of the birds to the city.
  "It's become a symbol of the facility," Mayor Stephen DiNatale said.
  While the city has had a permit for the two swans for at least the last decade, MassWildlife has soured on the introduction of these birds in recent years, according to Marion Larson, chief of information and education at MassWildlife.
  The birds at Coggshall Park, both female, were Mute Swans, a species native to Eurasia and northern Africa. However, the birds have thrived in the United States, with a large feral population in coastal regions, Larson said.
  "Their numbers have been swelling and they have expanded their range well into Massachusetts," she said.
  With the boom comes environmental problems. Unlike Canada Geese, which nibble, swans pull at the top of aquatic plants, causing problems with sediment and shoreline erosion, according to Larson.
  The birds can weigh over 20 pounds and are sometimes aggressive, particularly during breeding season, she added.
  "They don't have much problem going after someone in a canoe or kayak to defend their nest," Larson said.
  Due to these factors, MassWildlife has "encouraged folks to no longer have swans," she said, however the agency is still reviewing the permit request submitted by the city.
  She said she is unsure how many requests have been approved over the last five years, but it has been limited.
  According to Larson, the city's current permit -- which requires the birds to have clipped wings to restrict flight -- is specific to each swan and will not cover a replacement.
  No federal permits are required to purchase a swan, she said.
  DiNatale said if the city receives a permit, the next challenge will be finding a place to buy the bird, because they cannot be purchased in-state.
  "I have to get approval to purchase a swan so I can locate a swan to purchase and then get a permit to import the swan into the state," said city Recreation Director Nate LaRose, who submitted the request.
  LaRose said the city paid $25 last year for the permit. During the winter, the swans are caught by the Fitchburg Fire Department and stay at Hollis Hills Farm.
  LaRose said the remaining swan appears to be "doing OK."
  While the two swans were probably not mates, Larson say swans do recover from loss.
  "One of our biologists has a really great saying," she said. "They mate for life, but they only mourn for a minute."
  Follow Elizabeth Dobbins on Twitter @DobbinsSentinel.