About now (late January) I start to think of warmer seasons, and in particular look forward to the return of one of my favourite birds.
The swift is an unassuming little creature, just a few inches across and weighing no more than a few grams. On the ground a swift can seem slightly ridiculous, with its short legs and its centre of balance all wrong. But once it’s in the air it becomes a marvelous and mysterious creature, and without doubt one of the most accomplished flyers in the natural world.
We’ve still a lot to learn about swifts. For the first three years they never land, and when they do so it’s only for a few short weeks to breed. And though the parents, which mate for life, bring their chicks copious amounts of food while they’re in the nest, once the young birds take their first flight, they’re on their own. Many of them head straight for southern Africa, instinctively following long invisible paths that are thousands of years old.
Swifts usually fly low, at around 50 metres, where the greatest number of flying insects and airborne spiders are found. But on migration they can fly at heights of over 10,000 feet. They mate and can even sleep on the wing, half a brain at a time! And they hold the record for the fastest level flight speed of any bird, almost 70mph! They have few natural predators.
Which might lead you to think we needn’t worry too much about swifts. But swifts have a long history of involvement with humans, and like many such relationships, it is in danger.
Swifts are at their most vulnerable when they come to breed. Once they raised their chicks in crevices in cliff faces, but they soon learned that the nooks and crannies of tall buildings provided perfect substitutes in which to rear their young. For them, a draughty building is a bonus. But we don’t make buildings like that anymore, and we’ve blocked off many of the vents and ledges in older ones that used to suit them well.
It’s not just nesting sites. Modern agriculture and suburban gardening mean there are fewer insects for them to eat during the breeding season.
The swift, or martlet as it used to be known, has been with us for a long time. The martlet is a common feature in ancient heraldry, for instance. But now the RSPB classify the population as amber status, meaning they are in danger. I can remember swifts – and swallows and house martins – in abundance when I was growing up. Not so now.
One of the joys of swifts is that they are happy in an urban environment, and you can still see them swooping at breakneck speed between the rooftops and warehouses in our towns and cities. To my mind there are few pleasures as great as sitting in the garden on a warm summer’s evening just watching them fly.
I can’t wait for them to come back! Meanwhile, here’s a fine film about swifts, called Swift Stories.
Image by Dave Curtis, Creative Commons