Diseases among bird populations are on the increase and, as a growing number of households take to feeding their garden birds, researchers have claimed that bird feeders are contributing to the spread of dangerous pathogens, viruses and bacteria in certain species.
Scientists from both the Zoological Society of London (ZSL) and the British Trust for Ornithology (BTO) have learnt that poor cleanliness, the accumulation of droppings around feeders and the build-up of stale food are aiding the transmission of diseases between garden birds. A problem made worse by the tendency of feeding stations to attract large numbers of birds – including species who would not usually encounter each other at such close quarters in the wild.
Trichomonosis is a notable example of a disease whose spread is facilitated by bird feeders: a condition transmitted largely, it is thought, through contaminated food sources and caused by the parasite Trichomonas gallinae. This disease typically causes lesions in the back of the throat and in the gullet, preventing infected birds from eating and, over the course of several days, can lead to starvation. Although cases of the disease have been observed previously in pigeon, tit and sparrow species, it is primarily a condition affecting finches. Particularly Greenfinches, which have suffered a 35% decrease in population as a result – plummeting from 4.3m to 2.8m birds since the disease first emerged in 2005. This study, however, focused on more than just Trichomonosis – studying also the spread of bacterial Passerine Salmonellosis and viral Paridae Pox.
In order to combat the spread of diseases at feeding stations, homeowners are urged to follow sensible hygiene precautions: cleaning and disinfecting feeders and feeding sites using suitable disinfectants. These a weak solution of household bleach (5% sodium hypochlorite) or other specially designed commercial products. Feeders should always be rinsed and air-dried before re-use. It is similarly advisable to rotate bird feeders around the garden and to sweep/wash away discarded or uneaten food items from the ground beneath feeders.
Kate Risely from the BTO has offered advice to anyone who wishes to keep bird feeders safe and clean:
“We’re calling on everyone who feeds wild birds to be aware of their responsibilities for preventing disease. Simple steps we’d recommend include offering a variety of food from accredited sources; feeding in moderation, so that feeders are typically emptied every one to two days; the regular cleaning of bird feeders; and rotation of feeding sites to avoid accumulation of waste food or bird droppings”
If you, yourself, notice birds showing symptoms of Trichomonosis or any other disease in your garden, the RSPB recommends to temporarily stop feeding. At least until no further sick birds are found in the garden.