One of our latest returning migrants is the Swift. I always associate their screaming calls with warm summer evenings.. gathering in chasing groups, seemingly at brake neck speeds, they twist and turn their up the main street. Masters of the air, they have no need of the ground at all. A record speed for Swifts is 69 mph, in level flight, there’s no faster bird. The stats for Swifts are incredible: a young bird, once out of the nest may not perch again for two years when it is tempted in to eaves to start its nesting cycle. They can sleep on the wing, switching off one side of the brain; they even mate on the wing. With such mastery of the skies, it is not surprising that if they become grounded ( as young birds which fall from the nest, sometimes do), they are in trouble and are the one baby bird that can benefit from human intervention and be lifted back to a high ledge to launch a flight.
We only get to enjoy Swifts for about 10 or 12 weeks of the year, before they return to Africa. Recent research has tracked Swifts to their winter quarters in the Congo basin with further feeding movements east to Mozambique. Once back in northern Europe, Swifts need to find quantities of their favourite food: aerial insects and spiders. They are of course superbly adapted to this quest: a food ball for the nestlings may contain up to 1,000 tiny insects. If food supplies are scarce, due to poor weather conditions, for example, the young can survive without feeding by going into a state of torpor. The downside of this survival mechanism is that the fledgling stage can be as high as 56 days!
If you have nest records for Swifts, you can input to the National Swift Survey, visit birdwatchirelandswifts.blogspot.ie