Nature: Why you need to keep bird feeders clean
- Credit: Archant © 2008
Mike Toms says we need to make sure bird feeders don't cause disease problems.
The large numbers of birds visiting the garden feeders reinforces the importance of this food supply during winter. While putting out food in this way has been shown to increase overwinter survival, it is also worth remembering that its presence may, on occasion, cause problems. Wherever birds gather together in large numbers there is an increased risk of disease transmission. It is for this reason that bird tables and hanging feeders should be cleaned regularly (ideally weekly) by using a 'vet-safe' cleaning agent or a weak solution of bleach in water. It is also important to keep an eye out for signs of disease in the birds visiting your garden feeders. Symptoms of general ill-health, common to a range of diseases, include a fluffed-up appearance, lethargy and a reluctance to move away from the feeders if approached. In some cases, you may see wet plumage around the bill or notice a bird showing some difficulty in swallowing.
A protozoan parasite is responsible for one of the diseases now most commonly encountered in small garden birds – trichomonosis. This is passed between individuals through contaminated food or saliva, hence the need to keep feeders and feeding surfaces clean. Birds that have difficulty in swallowing because of the lesions that develop in the throat may regurgitate contaminated food that is then taken by other individuals. If you see ill birds in your garden then the advice is to stop feeding for 2-3 weeks and clean all feeders thoroughly. Bird baths should also be cleaned and rinsed thoroughly on a weekly basis.
Trichomonosis is not the only problem; others include salmonellosis (seemingly less common now), colibacillosis (caused by the bacterium Escherichia coli) and avian pox, the latter characterised by wart-like growths on the face or body. You may also see chaffinches with 'white' or scaly legs, evidence of one of two different diseases affecting this species. Feeding wild birds has many beneficial effects but it is also important to remember the responsibility to provide good quality food through clean feeders and bird tables.