Atlantic Canadians are being asked to keep their bird baths and feeders clean to help prevent the spread of a nasty parasite killing off finches.

'This could spread potentially to other kinds of finches.'— Maria Forzan, wildlife pathologist

The Trichomonas gallinae parasite is deadly to the American goldfinch and the purple finch. Both are common sights near bird baths and feeders in the region during the summer.

The parasite is carried in pigeons and doves, which it does not harm. But a finch sick with the parasite often has ruffled feathers and slow movements. It can also lose its ability to swallow seeds, leading to starvation.

Purple finches are among the birds falling prey to the Trichomonas gallinae parasite. (MacPhail Woods)Maria Forzan, a pathologist for the Canadian Co-operative Wildlife Health Centre in Charlottetown, has examined more than two dozen dead finches since the parasite first infected the birds in Nova Scotia in 2007.

"The bird that's regurgitating the affected seed has to be in close contact with the one that's going to eat that seed," said Forzan.

"That happens around bird feeders; it wouldn't really happen in the wild."

Forzan suggests people keep their bird baths and feeders clean, or remove them altogether if they notice sick or dead finches. Otherwise the problem could get worse.

"This could spread potentially to other kinds of finches and other types of passerine birds, which are basically, you know, the garden feeder birds," she said.

Forzan said the parasite has recently been found in the pine siskin finch.