Not a lot it would seem! I was recently sent some photos by Nik Knight, Chairman of the Hampshire Bat Group (for whom I recently did a talk on Swifts), of a pair of Swifts raising young within the cavity space of a wall. Nik used to teach at Portsmouth Grammar School until he retired in 2006.
Years previously, in 1986, builders were replacing the windows shown in the above photo (taken later in June 2009). The two right-hand arrows mark where Swifts entered their nests in the eaves and the left-hand arrow is the entrance hole for another nest. When the window above this hole was removed for replacement, the builder found that there were Swifts nesting in the cavity below. He took some photos including the ones below. This was in the pre-digital age and it’s difficult to make out whether there are two or three birds in the photo. The photo was taken in the school holidays so sometime from the end of July onwards. But how amazing that Swifts managed to rear young in such a small space. We know that Swifts are able to traverse and climb well on vertical surfaces with their sharp, powerful clawed feet but I’d love to know if, when travelling down to the nest, they went down head-first or tail-first. There is so much we still have to learn about these remarkable birds.
