Swifts are a remarkable species of bird. They’ve taken a life on the wing to the extreme and undertake feats no other species is capable of. But they are declining rapidly.
Swift Mapper, our latest project, is designed to crowdsource data on the location of nest sites and nesting swifts around the UK. Set up and run with the RSPB, this citizen science project is designed to put swift data into the hands of those who both need it and can help protect swift nesting locations.
A life on the wing
Swifts are migratory birds that arrive in the UK in May and depart in late July-early August. This makes them one of our shortest staying migrants along with birds like the cuckoo. Evolution has shaped these scimitar winged birds over millennia for a single purpose – a life on the wing. It’s a staggering fact that, from the moment a swift leaves its nest as a fledgling, it will not touch terra firma again until it breeds. This may be some 4 years later. They eat, sleep and even mate on the wing.
Because they spend such a large amount of time in the air swifts have evolved to have very small legs. Of little use for walking or perching their feet are, however, well adapted to clinging to vertical surfaces. This enables them to take advantage of nest sites few other birds can use. It was long believed they had no legs at all and their scientific name Apus is a derivation of the Greek apous meaning “without feet”.
Threats and adaptations
Like many of our bird species swifts are rapidly declining in number and we’ve lost over 50% of them in the last 20 years.
Dependence on humans – A double edged sword
Common Swifts have come to depend on humans almost entirely for nesting locations, and favour ageing roofs containing nooks and crannies, hence their affinity with old churches and less than perfect old roofs.
Colonial nesters, they use the same sites year after year and the simple nests are lined with feathers, winged seeds and other airborne flotsam they encounter.
Like many of our bird species swifts are rapidly declining in number and we’ve lost over 50% of them in the last 20 years. One factor is undoubtedly the loss of suitable breeding sites, as old roofs are repaired or replaced. So understanding where these sites are, and being able to monitor them, is critical.
Remarkable feats (despite the unremarkable feets)
It’s probable other factors are involved in the decline of swifts. Being totally reliant upon aerial insect prey (and a good number of drifting money-spiders), swifts are undoubtedly being affected by the global decline in insect numbers. They are also at the mercy of our erratic climate and nestlings face starvation when inclement weather sets in. Fortunately, however, chicks have been found to possess the ability to regulate their metabolism and can switch off and enter a torpid state for several days, thereby conserving vital energy. I do a similar thing at the weekends.
swifts are estimated to fly an average of 500 miles a day. This means that an adult reaching the age of 9 years could clock up an astounding 1.64 million air miles in its lifetime.
Even more remarkable are the extraordinary lengths that adult birds go to in order to find food; sometimes circumventing entire weather systems, many hundreds of miles wide. Birds, with nests in England, have been tracked over the Continent. And feeding forays well in excess of 1000 miles are thought not to be uncommon. In fact, swifts are estimated to fly an average of 500 miles a day. This means that an adult reaching the age of 9 years could clock up an astounding 1.64 million air miles in its lifetime. The irony is that all the Hilton vouchers are of no use to them at all.
The common swift is also officially the fastest bird in the world in level flight, reaching speeds of 70 mph. There is rumoured to be another species of swift that may be faster still – but we’ll have to wait and see if that’s true.
There’s still time – Join the fight!
For now, our own exhilarating species of swift, the herald and epitome of summer for many people, still fills the air with joyful screams and remarkable displays of aerial prowess. With luck and focused conservation effort they will remain a common sight for future generations to come. But, they need your help!
Submit your sightings of nesting swifts and/or swift nest sites on the new Swift Mapper website where you can also find links to the smartphone app.