Weekly Nature Watch

Country View 18.5.16

on .

Out of a clear blue sky they came … like exocet missiles! As the late Ted Hughes wrote, “They’ve made it again, which means the globe’s still working, the Creation’s still waking refreshed, our summer’s still to come …” Suddenly, for that is the way with swifts, there they were, hurtling among the chimney tops like demented dervishes, their wild screeching echoing across the village.

These scimitar-winged guided missiles, deliciously described by poet Edward Thomas, “As if the bow had flown off with the arrow!” seemingly all black but in reality dark brown, in some ways I suppose, complete the set of summer migrants. They are last to come, at least as a group, for unlike most other migrants, swifts make their journey from Africa, always at the same time, directly, rapidly and en masse. However, their stay here is surprisingly short – never more than about sixteen weeks. So along with adult cuckoos which, once their dastardly deeds are done, depart these shores in late July, swifts, arriving in May are gone again by early August.

Those clear blue skies, matched increasingly by the glorious, aromatic blue woodland carpets of bluebells – our world now both blue topped and bottomed - together with weather which has, we are told, emanated from the warmer climes of the Mediterranean, has helped many northbound migrants on their way. Everywhere I have been in the countryside during the past few days, seems especially to echo to the notably sweet sounds of willow warblers, their down the scale cadence a much welcome sound that surely spells … summer, just as much as that raucous screaming delivered by the hard flying swifts!

It isn’t that all the migrants have by now completed their journeys. Each day, brings more of them, warblers, cuckoos (far fewer than there used to be), ospreys and many more. Most of them make their way here at a relatively leisurely pace but the all-action swifts come in fast flying squadrons, usually arriving on virtually the same day every year. Swifts do not hide their lights under bushels, they proclaim their presence almost violently. As Hughes put it: “Shrapnel-scatter terror, international mobsters … Jockeying across each other - On their switchback wheel of death ….”

These are of course, the ultimate flying machines, so much so that most of them will have led an existence entirely on the wing since they abruptly left these shores last August. Swifts only touch-down when they nest and those too young to pair up will continue that airy existence throughout the summer… and beyond, through next winter ... and on and on! They feed, drink, and sleep (little more than cat naps I expect) sometimes at exceptional altitudes – as high as six thousand feet or more. One theory reckons that only one half of the brain sleeps, whilst the other half maintains alertness, rather in the manner apparently of dolphins! They therefore also rest and even mate on the wing. Indeed, they have little option for their legs are puny and pretty powerless.

However, life with hardly any form of terrestrial existence perhaps makes swifts much less vulnerable to predation for they are exceptionally long lived birds, with some known to have topped a lifespan of twenty years and most swifts averaging a life of around ten years.

A grounded swift is a stranded swift unless it can find a vertical surface to climb - although its legs are weak its feet are equipped with long claws - from which it can re-launch itself into the air. Hence, my encounter with a young swift some years ago stranded on somebody’s lawn and so thought to be mortally injured. Quick examination revealed no injuries and so I threw it into the air and it flew away! Aristotle by the way, called swifts ‘footless’ an observation which is still present in today’s scientific name for the bird, ‘apus apus’, which I understand translates from ‘a’, ‘without’. and ‘pous’, meaning ‘foot’.

Not surprisingly, swifts are, and indeed always have been, confused with swallows and martins. Although they earn their livings in much the same way – catching insects in flight with beaks gaping open, swifts are not closely related to either swallows or martins. The confusion is illustrated by some of the local names by which swifts are known; ‘black martin’, ‘brown swallow’ and ‘crane swallow’.  By virtue of their loud screaming, they also rejoice in appropriate pseudonyms such as ‘devil bird’, ‘screech martin’, devil swallow’ and ’devil shrieker’, amongst many others!

These days, since coal fires and the like have been banned in most large towns and cities, there are present above such places, many more insects than used to be the case. Thus there is for the most part a plentiful food source for swifts in urban areas. And as swifts do not bother with the chore of building much of a nest to speak of, they often make their home by creeping through little cracks in masonry and thus setting up their apology for a nest, largely on or in man-made structures, notably roofs. The only material you are likely to find in a swift’s nest is bits of flotsam and the odd feather or two, all of course, garnered from the air albeit that you are also liable to find a few large and unpleasant looking parasites there too! 

Swifts need good weather (don’t we all?). Incessant wet weather depresses insect populations, the swifts’ only source of food, but being such strong flyers, they are prepared to travel substantial distances to find places where insect life abounds, for instance in the wake of depressions where the insects are prone to gather in vast numbers. Swifts have been recorded making round trips of over a thousand miles to exploit such bounties. Consequently young, nestling swifts, in the event of bad weather, can descend into a kind of trance – a torpor – in which their whole metabolism slows down. In this state, they can survive without food for some forty eight hours or more.

Swifts are indeed high flyers. It has been estimated that a swift generally flies on average, at least five hundred miles on every day of its life, which probably means a total lifetime distance of way over a million miles! One from a farmhouse in Gloucestershire is known to have clocked up over three million! And as swifts are generally not thought to breed until they are four years old, the youngsters produced in local nests this summer may well get close to notching up a million miles before they next feel terra firma beneath their puny little feet again!

Swift by name and very definitely swift by nature … but not on the ground!

Any natural place contains an infinite reservoir of information, and therefore the potential for inexhaustible new discoveries.

Richard Louv, Last Child in the Woods