5 things you might not know about the swallow
Swallows are one of my all-time favourite birds. You won't find them on a feeder, but if you spot one swooping overhead it feels like summer has properly arrived. Here are five things about them that I find hard to believe.
1. A mud nest takes two weeks, so they keep them
Building a nest from mud takes around two weeks, so old nests are highly valued. Reuse for ten to fifteen years is normal, and one nest was reported to have been occupied for forty-eight years. Swallows will also use artificial nests if there is wet mud nearby.
2. Their journey can top 7,000 miles
Swallows spend the winter in southern Africa and return to Britain each spring. Annual migrations of up to 11,660 kilometres, around 7,250 miles, have been recorded. The first proof of the link between Britain and South Africa came from a swallow ringed in Staffordshire and found in Natal in December 1912.
3. Nobody shows the young the way
The swallows leaving us now were only born this summer, and their parents don't lead them. They have never seen the route and have no idea where they are going, but they are born knowing what to do: head this way, for roughly this long. They hold their direction by reading the Earth's magnetic field, not like a compass needle, but by the tilt of its lines. Scientists believe they may actually see it, as a pattern laid over their vision that shifts as they turn their head, so they keep turning until what they see is what they expect to see, and then fly for as long as they expect to.
4. A longer tail makes a better mate
The long outer tail streamers measure between two and seven centimetres, and males with longer streamers tend to breed more successfully. Males arrive first, about two weeks ahead of the females, to defend nest sites. In Denmark, average male tail length rose by 9% between 1984 and 2004.
5. Millions roost in one place
A reed bed in Durban, South Africa, serves as a night roost for more than three million swallows, about 1% of the world's population. Life is hard, though: first-year mortality averages 70% to 80%, and most swallows live under four years.
A little swallow folklore
It's said that swallows will only nest where peace and happiness reign, and that destroying a swallow's nest brings terrible luck. Superstitions once held that damaging a nest could make cows give bloody milk or no milk at all, or make hens stop laying.
Sailors traditionally had a swallow tattooed after 5,000 nautical miles at sea, and a second after 10,000. People say that if swallows fly low, rain may be on the way, though it is more likely to be insects flying closer to the ground in humid weather. For centuries many people believed swallows spent the winter hibernating in mud at the bottom of ponds, and even Gilbert White was unsure whether they migrated or hibernated.
The Greek philosopher Aristotle gave us the line: One swallow does not a summer make.
How to help swallows
Swallows catch their food on the wing, so they will never visit a feeder, but you can still help. Leave a muddy patch where they can collect nesting material, keep outbuildings open if you have them. The best thing you can do for them is the same as for every other bird: a garden full of insects. Our seasonal bird food will keep your garden birds going while the swallows are away. If you are not sure which feeder suits your garden, our feeding quiz will point you in the right direction.
Want to keep track of the swallows in your garden? Amidst the Birdsong: A Garden Birdwatcher's Journal is made for exactly that.
Want to read about more garden birds? See all the birds in this series.
