Country: Nature Note
Saturday 12 September 1998
As late as the 18th century, scientific observers believed that swallows spent the winter hibernating under water.
Even that great savant, Dr Johnson, thought that "a number of them conglobulate by flying round and round and then, all in a heap, throw themselves under water and lie in the bed of a river".
Ringing has shown that they fly several thousand miles to southern Africa: it has been estimated that after a good breeding season in Europe, some 220 million of them will head for the far south. British swallows seem to favour the area round Johannesburg.
Scientists are still not certain what triggers their annual departure, but one key factor appears to be the shortening of daylight hours.
Nor do experts agree on how the birds navigate: they appear to steer partly by the sun, partly by landmarks, and partly by responding to the earth's magnetic field.
Swallows are specialists at in-flight refuelling: they eat as they go, catching insects on the wing, swooping low over lakes or rivers to drink, and pitching into reed-beds to take a rest at night.
The best TV shows and films coming to the servicetv
Watch the new House of Cards series three trailerTV
Oscars 2015It was the first time Barney has compered the Academy Awards
Oscars 2015 From Meryl Streep whooping Patricia Arquette's equality speech to Chris Pine in tears
Oscars 2015 Mexican filmmaker uses speech to urge 'respect' for immigrants
TV ReviewThe intrigue deepens as we delve further but don't expect any answers just yet
Razzies 2015 Golden Raspberry Awards 'honours' Cameron Diaz and Kirk Cameron
Arts & Ents blogs
- 1 End of the licence fee: BBC to back radical overhaul of how it is funded
- 2 This restaurant has misunderstood the concept of 'cheese and biscuits'
- 3 Raif Badawi, the Saudi Arabian blogger sentenced to 1,000 lashes, may now face death penalty
- 4 Delhi bus rapist blames dead victim for attack because 'girls are responsible for rape'
- 5 PornHub turns masturbation into energy in bid to save the planet
Game of Thrones season 5 spoilers: What we can expect according to George RR Martin's books
Spectre: Director Sam Mendes teases clips from upcoming James Bond movie
Indian Summers recommissioned: Channel 4 confirm a second series of British Empire drama
Fifty Shades of Grey movie shows first sex scene 'after 40 minutes'
The Casual Vacancy finale review: Superb cast, luscious cinematography - shame about the confused ending
New theory could prove how life began and disprove God
This is what it's like to be dead, according to a guy who died for a bit
End of the licence fee: BBC to back radical overhaul of how it is funded
'Jihadi John': CAGE representative storms off Sky News accusing Kay Burley of Islamophobia
Ukip would cut billions from Scottish budget to fund English tax cuts
Nearly 100,000 of Britain's poorest children go hungry after parents' benefits are cut