People in Britain feed up to 196 million birds a year with 60,000 tonnes of bird food, at a total cost of £300 million. All those garden feeders have helped boost populations of dozens of bird species, including the garden regular, the blue tit, whose numbers have increased by 26% in the last 50 years.
But could our benevolence be harming birds? In Germany, a fatal pneumonia-like illness has been affecting several thousand blue tits. Laboratory tests confirmed that the organism responsible for the outbreak was a bacteria called Suttonella ornithocola, which is well-established in British blue tit populations too, with cases of the disease usually peaking in spring time. Symptoms include loss of appetite, breathing problems, ungroomed feathers and a willingness to approach humans, while healthy birds would tend to avoid us.
S. ornithocola was first isolated from the lungs of a blue tit in the 1990s and has since been found in other tit species, although the blue tit seems to be the most susceptible. In the UK during springtime, the disease is thought to be responsible for as much as 13% of all blue tit deaths. MORE
Header image: Some of the birds visiting a feeder in a park near Newton Abbot, Devon, UK. Credit: Richard Austin.