Parasitic infection killing greenfinches


A DISEASE which cannot be controlled in the wild is killing off one of Ireland’s most popular garden birds, the greenfinch.

While trichomoniasis, caused by the parasitic trichomonad organism, has been hitting all bird populations, greenfinches have been the species most affected.

The parasite lives in the bird’s upper digestive tract, its actions progressively blocking the bird’s throat, making it unable to swallow, thus killing it by starvation.

According to Oran O’Sullivan of BirdWatch Ireland, its records have shown greenfinches have declined from seventh to 10th place in the most commonly observed birds in gardens. “This is the most accurate indication we have of falling numbers and we are concerned about what is happening, especially when the disease cannot be controlled in the wild.”

The disease was first noticed about four years ago when Birdwatch began receiving reports of garden birds dying. The main outbreaks are during the late summer and autumn, but there are already signs of an outbreak in 2009.

“Greenfinches have been the species most frequently affected, but other finch species and house sparrows are also susceptible to the disease. Formerly, this disease has been recorded in pigeons and doves, as well as in some birds of prey and game birds.”

Mr O’Sullivan said birds with the disease showed symptoms such as lethargy and fluffed-up plumage, but affected birds may also drool, regurgitate food, have difficulty in swallowing or show laboured breathing. Finches were frequently seen to have matted wet plumage around the face and beak. In some cases, swelling of the neck may also be visible.

He said transmission of the infection happened when birds fed one another with regurgitated food during the breeding season and through food or drinking water contaminated with recently regurgitated saliva or droppings from infected birds. “If you spot sick birds in the garden,” Mr O’Sullivan added, “stop feeding them immediately, clean all bird baths and feeders and move them to another part of your garden.”