If you hear a screeching sound in the sky anytime between May to August, you’ve probably hearing swifts. They are fantastic birds which spent winter in Africa, south of the Sahara and the summer months over Europe where they will feed on insects and breed.
It’s a medium-sized aerial bird, and a superb flier. It feeds by catching flying insects and it famously even sleeps whilst in flight! It is plain sooty brown, but in flight against the sky it appears black. It has long, scythe-like wings and a short, forked tail.
The birds are regular and numerous summer visitors to Chatou and I watch them circling above the house, particularly in the morning and evening. Normally they are quite high but they can come down to roof top level. We are situated close to the river Seine, a hot spot for insects and maybe this makes it a good location for swifts.
Swifts are happy to nest in man-made environments, many buildings are constructed integrating special bricks which include nesting chambers and entrance holes for the birds. They will also use special nest boxes but these need to be installed at least 4-5m off the ground level.
The birds arrive from Africa at the beginning of May and will leave on the return journey by the end of July or early August. Therefore nesting will typically need to be underway by the end of May.
Chatou Nature Blog 