Parasitic disease poses threat to greenfinches

ROGER RATCLIFFE Published: 07:00 Wednesday 10 January 2018

The most troubling development in the world of garden birds in recent memory has been a steep decline in numbers of greenfinches caused by a disease known as Trichomonosis. 

Pigeon fanciers call it “canker”, while to falconers the condition is “frounce” but whatever the species the effect is identical. The parasite Trichomonas gallinae causes a swelling at the back of the throat which leads to a progressive difficulty in swallowing and breathing by inflected birds.

You know you are looking at a tricho bird if it is lethargic, gapes frequently and has fluffed-up plumage. I first noticed the condition in Yorkshire greenfinches round about the year 2000, and by 2006 a full scale UK epidemic was declared by the British Trust for Ornithology. Its most recent annual BirdTrends report, published just before Christmas and so given little publicity, highlights that the country’s greenfinch population has suffered a “rapid and alarming decline” of 59 percent.

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