I was told today of a garden bird feeding site where the owners had found several dead Greenfinches and where it was obvious they had died of disease. It appears this would be a form of Trichomonas - see below:

www.defra.gov.uk/animalh/diseases/vetsurveillance/species/wildlife/index.htm

It affects Greenfinches, Goldfinches and House Sparrows mainly.

At the site involved, intensive hygiene measures have been undertaken to eliminate it, and no more deaths have been noted. Bird tables and bird baths need to be scrubbed out weekly with a bleach solution, or a proprietary solution available from Jacobi Jayne called Chevi-col. Pigeon fancier suppliers may also stock this product.

The BBS results this year showed a 9% decrease in Greenfinch, which is unusual, so maybe this is one cause?