WE saw the first swifts of the year on Tuesday evening, May 5, when they arrived from their winter quarters in sub-Saharan Africa. It is always a joy to see them wheeling high in the sky and to hear them as they race round rooftops in ‘screaming parties’. Here’s a good piece of film from Denmark:
It is hard not to think they are enjoying themselves.
If there were a competition for Most Amazing Bird, the common swift (Apus apus) would certainly be a contender. It does everything to the extreme.
It is one of the fastest birds at level flying, having been recorded at nearly 70mph (a peregrine reaches 200mph when diving on prey but that is gravity-assisted). It flies further in its life than any other bird, not only because of the 14,000-mile migration round trip but because it spends almost its entire life on the wing. Swifts can live to the age of 20 (though rarely do) and it has been calculated that in that time a bird would fly about 4million miles, the same as to the moon and back eight times.
So they feed in the air, on insects and other tiny airborne creatures, they collect nesting material in the air, they can mate in the air, and they sleep in the air. In the evening you can see them circling higher and higher. One magical night in July we sat drinking wine in the garden until almost 10pm watching them until they disappeared from view. They may reach a height of two miles, then the theory is that they sleep while gliding gradually down overnight. It has been suggested that they can have half of the brain asleep at one time while the other half stays awake. The only time they come to land is to drink, as seen in this film:
and to nest. This is where they are in trouble, because although they must have originally nested in caves or tree holes, they discovered that they preferred man-made structures, under tiles, in eaves, in lofts, spires and towers. Refurbishment of old buildings and replacement with new ones has deprived them of much nesting space. Pesticides which kill their insect food do not help either, and between 1995 and 2016 we lost over half of all the swifts breeding in the United Kingdom. The present population is estimated at about 60,000 breeding pairs. If you want to help them you can buy nest boxes, which they are happy to use. See here for ideas.
Swifts pair for life and often return separately to the same nest year after year. They have two or three chicks, the parents taking turns to brood and hunt for food. They bring back balls of insects, possibly 500 or even 1,000 to a ball. Yet another unique feature of swifts is that if there is a period of bad weather and food is scarce, chicks can reduce their metabolic rate and survive on their fat reserves for several days. Egg development can also be suspended if the weather is very cold, something that would kill the embryos of any other bird.
When they are two to three weeks old the young swifts start to move about and exercise their wings by performing ‘press-ups’ on their wing tips.
In a good year they are ready to fly at about six weeks old. For several days before leaving the nest they spend long periods at the nest entrance looking out.
Here is a film of the big moment for one chick:
And that could be the last time the little bird is on his feet for four years, as that is the age at which they usually start to breed and therefore return to earth. Not only that, but as soon as they leave the nest they are independent of their parents and within a few days they will start their flight to Africa in the company of other fledglings. I find that almost unimaginable.
The swifts stay in Britain only long enough to breed, about three months. They start leaving in late July. First off are birds which are too young to breed, or unsuccessful breeders, and fledglings. Breeding males follow next, and finally the breeding females. These stay longer in the nest to rebuild their fat reserves. The journey takes two to three months.
Gunnera news: They are doing well but frost is threatened tomorrow night. You can see the damage from the last frost on the left-hand plant.
This is last week’s picture:
And this is yesterday: