Fewer greenfinches?

Greenfinches and goldfinches are the most numerous birds in our garden. There are occasions, especially mid morning, traditionally our busiest time, when every perch on our sunflower seed feeders is occupied by one or the other.

However this winter we think we’ve noticed fewer greenfinches than previously. I say `think’ because we’ve no actual proof as we weren’t counting weekly numbers last winter as we are this winter (for the BTO Garden Birdwatch). Its simply a feeling based on our memory of a garden green with the birds to a garden now where there are more goldfinches day to day.

Next winter when we can properly compare numbers, we’ll know if there’s any foundation to our assumptions. However, greenfinch declines have been noted elsewhere. The most recent Breeding Bird Survey report for Bristol has revealed a huge decline in birds since 2005.

Until we have proper evidence, the reason for these declines is a matter of speculation. However, one possibility is the well documented appearance of trichomoniasis in the species in 2005. Trichomoniasis, or `tricho’ for short, is a condition brought about by the trichomonad parasite.

This parasite infests the upper digestive tract, preventing the bird from eating properly, eventually killing individuals unfortunate enough to pick it up. Symptoms are easy to spot. A greenfinch with tricho has a `plumped up’ appearance, clearly struggles to eat, gulping at the food, and is incredibly lethargic, staying put if you approach when all the others have flown off. They are a sorry sight.

The parasite is passed via saliva and birds catch it from one another at busy feeding stations, although, unlike salmonella, it’s not linked to unhygienic bird feeders and tables. Sadly we had one in our own garden late last autumn, the time when occurrence is at it’s peak. The only way to attempt to deal with it, is to stop bird feeding for a few days, and thus stop the parasite being passed from bird to bird. Clearly though this will only really work if every one else in the neighbourhood does the same, and that’s difficult.

Tricho was unknown in greenfinches prior to 2005 and its appearance is a mystery. Its also being seen in goldfinches, but to a lesser degree. It is possible that the disease is having an impact on the greenfinch breeding population, and consequently we are seeing fewer winter birds. We’ll have to wait for further work to be done to establish if this is actually the case.

If it is, what can be done? As there’s no treatment that can be administered in the field we might simply have to wait for the finches to build up resistance to the parasite and, over this period accept a smaller population.

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  • About

    In this blog we'll describe the day to day comings and goings of the birds in our Devon garden.
  • About us

    Tony is a naturalist and environmental artist. Laura is a free range creative web and print designer. We've recently moved from the village of Ipplepen to the town of Newton Abbot with our two children Ralph and Oli, our dog Henry, and numerous cats (none of whom would ever dream of eating birds).
  • Species List

    List of species, including only those birds that land in the garden:
    Blackbird
    Blackcap
    Blue tit
    Brambling
    Bullfinch
    Carrion Crow
    Chaffinch
    Chiff chaff
    Coal tit
    Collared dove
    Dunnock
    Fieldfare
    Goldcrest
    Goldfinch
    Great spotted woodpecker
    Great tit
    Greenfinch
    House Sparrow
    Jay
    Long tailed tit
    Magpie
    Mistle thrush
    Nuthatch
    Pied wagtail
    Redwing
    Robin
    Siskin
    Song thrush
    Sparrowhawk
    Starling
    Wood pigeon
    Wren

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