As John mentioned, this weekend is the Big Garden Birdwatch in the U.K. The event is run by the Royal Society for the Protection of Birds to monitor trends among common European birds. Results from previous surveys indicate severe declines in the population of house sparrows and starlings. Meanwhile, chaffinchs and great tits have grown in number. According to the BBC, over 400,000 people participated last year.
North America has similar event coming up in a few weeks - the Great Backyard Bird Count. As always, the GBBC will fall on Presidents Day weekend, February 15-18.