The arrival of summer proper is announced with July. So what sort of spring was it? April was chilly, well below what we might have expected.
May was likewise, much of it again plagued by spiteful northerly winds which as a gardener I have come to dread. June was marginally improved if not “exactly busting out all over.”
The familiar screams of swifts (Apus apus) are once again with us for the summer and their cries have inevitably triggered childhood memories for me. Swifts are among the first of our indigenous birds to have lodged themselves firmly in my consciousness and I recall vividly summer evenings in Swanshurst Park, Birmingham, hours spent prone on the grass gazing skywards at these extraordinary birds. I recall also the futile attempts of less-caring lads who threw stones at the birds hoping to ground odd one, I thankfully cannot recall a single success.
Perhaps what is most amazing about swifts is the fact they spend almost their entire lives on the wing. From the moment a young swift leaves its nest until it returns to breed as an adult, it remains airborne. I have never quite been able to grasp what this astonishing life style, sleeping and feeding and maybe even mating on the wing, implies for swifts. I really cannot imagine what bizarre metabolic happenings take place in such an animal!
At first sight swifts should be related to swallows and martins: they are, however, completely unrelated. For the more scientific among us swifts belong to the order Apodiformes which means “legless”, while swallows and martins belong to the order Passeriformes which means “perching birds”.
There are quite obvious differences between swifts and their apparent relatives which are soon evident to the observer. Swifts appear as all black as they hurtle past, whereas swallows have obvious white breasts and definite glossy blue plumage. The smaller house martin has a conspicuous white rump. Confusion with the brown and white sand martin is unlikely, there are sadly a few locally. There are other differences: swallows and martins are stockier birds than the scythe-winged swifts and there is that unmistakable screaming call as groups of swifts zoom through the summer skies scooping up insects which in high summer are found in considerable volume floating as “ariel plankton.”
Swifts are among the last of our summer residents to return, arriving in late April or early May. They also among the first to depart, leaving in August. Their breeding season is therefore extremely brief. If this summer does not rapidly improve after a chilly spring there should be many a swift to question the wisdom of migrating to and from Africa twice a year. The serious answer must obviously be that the long days of our Northern summers do provide enough of a food supply to make it worth all that effort. My own unscientific view is that all swifts suffer from sort of masochistic tendency!
Nest locations are usually nooks and crannies in old roofs, church towers being rather favoured where nest material such as straw and feathers gathered, of course, in flight is used to form a warm bed for two or three white eggs, a frequent colour for species which nest in such dark places. The young are hatched blind and naked from extraordinarily elongated eggs. The shape is an evolutionary adaptation to prevent rolling. The apparently vulnerable young are, it seems, remarkably resistant to chilling and long periods without feeding as in the case of a cold spell. When conditions are favourable the young gain weight rapidly gulping down bundles of insects cemented by saliva in their parents crops.
Due to their strange life-style swifts face almost no threat from natural predators. In fact their only acknowledged predator is that glorious little falcon of southern heathlands, the Hobby which is about the only thing capable of matching the swifts speed. Swifts do, however, suffer from infections of blood sucking insects. Some years ago while working as a laboratory technician in Birmingham, I was presented with a juvenile swift which had obviously not quite managed its maiden flight and had found itself stranded on the ground. Due to the unfortunate bird’s “legless” condition and its extra long wings it was unable to get airborne again. Before finally launching the bird I had the unsavoury task of attempting to remove some of these revolting parasites.
The very nature of swifts makes the species a rather mysterious bird and there is no shortage of myth and folklore surrounding swifts, in particular they are blessed with several colloquial names. “Devilling”, “Skir-Devil” and “Devil Bird” are all ancient names which imply some sort of satanic connection. I suppose ignorant folk might well have seen some kind of supernatural link in the dark shapes which arrived out of nowhere every spring screaming and squealing from the skies. Thankfully we are more appreciative of these fabulous birds these days although, for me, they will always be rather marvellously mysterious.