TORONTO -- Wildlife experts are still working to rescue a sick swan trapped in a Brampton, Ont. pond.

The female trumpeter swan is too ill to fly and animal activists believe it is suffering from lead poisoning.

“This female had cygnets on this pond but what happens is they move south about one kilometre away to a pond known to have high lead levels,” local resident Renzo Dalla Via told CTV News Toronto.

The contaminated pond is near the site of an old gun range, which closed nearly 20 ago. The pond is just south of Sandalwood Parkway beside Highway 410. There is fencing around the property and no trespassing signs to keep people out, but the swans continue to go to the area to feed.

“The problem with the swans is they have great reach and they get deep down into the water and I think they are picking up leads oxide causing them to be sickened,” Dalla Via said.

Retired Veterinarian Maureen Harper says the sick female is separated from her mate and her last surviving cygnet. For two straight days, staff with the Toronto Wildlife Centre have attempted to rescue the swan.

Tuesday’s effort was called off when the swan moved to a difficult spot to reach. There is a thin layer of ice, which can make it dangerous for rescuers. Officials say they will make another attempt on Wednesday.

Harper says if they can rescue the swan, it can be treated.

“These swans are very intelligent. We almost lost them in the 1930’s we were down to 70 remaining. A reintroduction program has been successful in bringing the numbers back,” Harper said.

A spokesperson for the ministry of the environment says the government is aware the pond is contaminated with lead.

The land is owned by a real estate development company. The ministry says the company plans to install a cap on the wetlands next fall to provide a barrier to the contaminated sediment.