Our balcony in Lewes attracts a lot of birds, especially Greenfinches. In the past week we have found two Greenfinches dead on my balcony.
We had thought that several of them had looked rather odd. They were all puffed up as if against the cold, yet it was summer. We thought they must be due to moulting, but no. They were suffering from trichomonosis, a disease caused by a microscopic parasite. I contacted the RSPB. They informed me that since 2005 there have been outbreaks during the late summer and autumn.
They have been studied by the Garden Bird Health Initiative, of which the RSPB is part. Greenfinch populations have been recorded dropping by a third, and chaffinch populations by a fifth in those parts of the country that suffer the most serious outbreaks.
Other finches and house sparrows are also susceptible. Trichomonosis cannot be passed on to humans.
The trichomonad parasite lives in the bird’s digestive tract. It progressively blocks the bird’s throat, making it unable to swallow food.
The bird dies from starvation.
Birds with the disease show signs of general illness, for example lethargy and fluffed-up plumage, but affected birds may also drool saliva, regurgitate food, have difficulty in swallowing or show laboured breathing.
Finches are frequently seen to have matted, wet plumage around the face and beak, and uneaten food in and around the beak. In some cases, swelling of the neck may be seen from a distance.
What to do if you spot the symptoms - the RSPB recommends you temporarily stop putting out food, and leave bird baths dry until sick or dead birds are no longer found in the garden.
This is to discourage birds from congregating together, which may increase the potential for the disease to spread between individuals.
You can help by reporting an outbreak via http://www.ufaw.org.uk/gbhi.php.
Everyone can help generally by ensuring they regularly clean feeders, bird baths and feeding surfaces.