Girton Birdwatch - November 2007
It is distressing to draw your attention, once again, to the killer disease trichomoniasis which is affecting the region's garden birds. Last year we largely escaped the disease, which was concentrated in the West Midlands and Wales, but this year major clusters have been detected in the South West and East Anglia, with numerous reports flooding in from Norfolk for the first time. North Walsham seems to have been particularly hard hit. However, Jean Lawrence wrote to me at the end of September about several greenfinch deaths in her Church Lane garden, and just the other day we had a collared dove in our own garden exhibiting one of the symptoms of the disease, an enlarged throat. Green finches appear to be especially susceptible to the disease, but it has also been confirmed in chaffinches, bullfinches, goldfinches, house sparrows, dunnocks, great tits, blackbirds, yellowhammers and siskins. The parasite which causes the disease - trichomonas gallinae - has been common among pigeons and game birds for a number of years (often spreading to their predators) and is treatable with drugs in captive animals. Its sudden spread to small wild bird species is puzzling scientists and, because these birds fly freely, they cannot be helped by medicine. The birds starve to death because the parasite swells their throats, preventing them from eating. Often birds with the disease show signs of lethargy and will not fly away when approached. They may also suffer from fluffed up plumage, drool and regurgitate food, and have laboured breathing. Nobody knows how many birds have died of the disease as inevitably many cases go unreported but the volume of reported cases is already outstripping the levels of last year. The RSPB received reports of 346 suspected cases last month - many involving multiple deaths - compared with 152 during the same period of last year's outbreak and 20 in August 2005. The disease is most prevalent in late summer and early autumn so we can expect reported numbers to go on increasing.
The infection is passed on through saliva. As the birds dribble on to bird tables, baths and feeders, the parasite is transmitted by infected food and water. The RSPB is warning householders to disinfect bird baths and tables and to stop putting out food if they find dead birds nearby, to help prevent the spread of infection. Andre Farrar, a spokesperson for the RSPB, recognises that: 'The fact that doing something that is benign or good, like feeding birds, could be causing the spread of disease is clearly distressing to people'.
It may be useful to repeat the RSPB's full range of advice:
The parasite does not constitute a health threat to humans or mammals such as dogs and cats but does have the potential to affect captive poultry and pet birds.
The RSPB is part of a scheme called the Garden Bird Health Initiative which studies garden bird health and disease outbreaks. It is appealing for anyone who finds sick or dead birds in their garden to get in touch so it can monitor the spread and intensity of disease outbreaks. Go to www.rspb.org.uk and click on the downloadable registration form or call 0207 449 6685.
Have you noticed the large numbers of jays around the village? This is normally a shy bird but in Autumn it becomes very much more conspicuous. It may usually be seen flying high over the trees with a characteristically halting, rump-up/tail-down action which one commentator thought looked more like 'swimming … than flying'. They are collecting and hiding acorns at this time of year and seem to remember where they bury most of them, although inevitably they do sometimes forget and have been credited with a major role in the maintenance and spread of oak woodland. The bird's dependence on the oak means that any failure in the acorn crop can lead to substantial influxes of continental jays, although I have not heard of any suggestion that this is responsible for the large numbers this year. 'Large' is relative, given that in 1983 1800 were seen in an hour near St. Just, Cornwall! Enough to give an old-fashioned game-keeper a heart attack.
Three bramblings were seen flying over the village on 14th October; I really must go in search of this bird this Autumn as I've only ever seen the one.