The recent British Trust for Ornithology's Garden Bird Feeding Survey has found that the Blue Tit bird has fallen in numbers by an alarming 42% over the last 40 years. In addition the numbers of starlings and song thrushes has dropped by 75% and house sparrows has also declined rapidly by 70%.
Tim Harrison for the British Trust has commented that bird feeding in UK gardens may be responsible. The availability of bird food on bird feeders means that the blue tit in particular is facing competition from other birds and animals. The blue tit would usually have been able to get to food sources which were inaccessible for other species, giving it an advantage. The use of bird feeders also means that birds are more widespread across a number of gardens.
Also from the Trust, David Glue points out that the survey is a wonderful resource and shows how the urbanisation of birds is affecting their populations. He believes that the importance of the survey, which is carried out on a voluntary basis by home owners around the country, will continue to grow.