Some of the birds, though, were far more mobile, covering vast areas of Africa, and when making the return trip to the UK, some of them covered distances of more than 17,000 miles, 5,000 more than the actual journey length.
If you thought you knew what speed was, think about the tiny birds called common swifts – Apus apus – which have been recorded, during their return migration from Africa to the UK, completing the 3,100 miles journey in five days only.
They managed to maintain average speeds, during the non-stop journey, of around 25mph. They need not stop for the simple reason that these 6 in long birds can both eat and sleep on the wing. In fact, before beginning their epic flight, they will have spent around ten days fattening up on flying termites in Liberia, west Africa.
The British Trust for Ornithology is investigating what reasons might lay behind the decline of this bird species, 33% of British swifts disappearing since 1995, partly due to loss of suitable UK nesting sites, though as the birds spend only around two months a year there, other factors must play a part in their decline.
Special trackers were fitted to to 15 birds, to monitor their movements upon leaving the UK. These so-called geo-locaters weigh only one fiftieth of an ounce, recording light intensity, and when this data collated scientists can accurately track when and where the birds travelled.
This data was only downloadable once the devices were removed, so the birds involved were temporarily captured, the findings only just released. Southward routes followed by the birds followed roughly what ornithologists expected, the birds flying via Spain and west Africa, before heading across the African continent to the Congo, where they tend to spend the winter months.
Some of the birds, though, were far more mobile, covering vast areas of Africa, and when making the return trip to the UK, some of them covered distances of more than 17,000 miles, 5,000 more than the actual journey length. These most aerial of small birds are really quite incredible, with their distinctive shape in flight – long, scythe-like wings and a short, forked tail, seen in the UK at the height of summer – one of the last summer migrants to arrive and the first to leave – numbers estimated at around 85,000 breeding pairs.
Swifts spend their lives almost entirely on the wing – mating, eating and feeding in flight, though their astounding turn of speed is nothing compared to that of Great Snipes – much bigger birds known to cover 4,200 miles in three and half days – averaging 60mph, but as far as little birds are concerned they are genuinely swift.