It is well known that a small number of Common Swifts, Apus apus, do not nest in houses or churches. In the old Caledonian Pine forests in Abernethy Forest in Scotland a small number nest in trees. There is a lovely video of Iolo Williams from Springwatch 2019 where he watches the interaction between a Swift and a Great Spotted Woodpecker as the Swift returns to its nest in an old woodpecker hole in a Scots Pine tree. You can watch the clip here.
Ancestrally, this will have been where Swifts nested until they started to use man-made structures instead, and a few still nest in trees in the ancient forests of Finland, Poland and Germany.
And some Swifts nest in quarries and even chalk pits. In England I don’t know how many pairs nest in situations like this, but Gilbert White wrote of several pairs of Swifts nesting in a chalk pit near Odiham - I’ll write more about that in a later blog. In Northern Ireland surveys of quarries there have shown Swifts nesting in various places. Many thanks to Mark Smyth for the photo below.
But do Swifts nest in man-made structures other than houses and churches? Yes, occasionally they do. There was a small colony in Huntingdon railway viaduct until this was demolished a few years ago as part of a massive road re-engineering project in the area. The Swifts gained access through the 100mm drainage holes in the underside of the concrete box sections that made up the bridge spans.
And what about here in Hampshire? In July this year, Wendy Reid was driving out of Fordingbridge under the A338 road bridge and happened to see a low screaming party of six Swifts next to the bridge so decided to investigate on her return. As she was driving under the bridge coming back into town the swifts flew under the bridge and up into a nest. What luck!
The birds nest on the south side of the bridge, the right-hand side in the photo above. We don’t know how long they have nested here or even how many there are, but it seems there are at least three pairs. The birds nest in the narrow gap between the insitu concrete wall and the horizontal planks above. The birds were only discovered this year just as they were about to fledge in mid-July, so a more detailed survey will be carried out next year. I wonder how common this is in the county - it is certainly the only bridge that we know about that has Swifts nesting, but then how often do people look at these sites?
Postscript - I have since heard from Stephen Fitt (RSPB volunteer in the SW) who has read this blog and reports that the Dorset Bird Club reported many years ago that there were four pairs nesting under this bridge back in 2010 - so it is not a recent colonisation.
Location of Swift nests in 2022