More than a quarter of Britain’s birds are now on the RSPB’s red list, meaning that their numbers are in severe decline. Some of the recent additions to the red list are thought of as common garden birds, such as the greenfinch. Others, such as the swift and house martin, only spend spring and summer visiting the UK before migrating to warmer climes. But the environment they encounter in the UK, as well as along their migration routes, affects their survival significantly. Many of the species that we feed in our gardens and on balconies are under threat. Here are four ways to help them. 1. Clean your bird feeders and bird baths In the wild, with a few exceptions such as starlings, birds don’t come into close contact with each other much. This lack of contact makes it harder for diseases to spread. Bird feeders change this dynamic. The …