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NATURE The not-so-common swift

Outdoor Living
Life on the wing

The common swift is, ironically, less common than it once was. John Shelley takes a look at these remarkable little birds and why their numbers are declining.

A small company of swifts passed overhead, cutting through the air on scythe-like wings and screaming as if with excitement, perhaps in anticipation of the long journey ahead. They paused for a while as a mere shadow of summer, plunging almost to the surface of the lake to take a final snack before departing, and when I looked again they were gone, leaving the afternoon sky empty and quiet.
Even now these common swifts must have left the country, passing through the south of England and from there into France and Spain. The Mediterranean Sea is nothing to them, nor the mighty Sahara, which presents such a challenge to many other migratory bird species. Farther to the south seasonal rains keep the land lush and keep insect populations high. This is where our swifts will spend the next eight months before the time comes for them to visit us once more. Imagine, more than ten thousand kilometres lie between here and there, yet to these hardy travellers a few flies will be enough to take them there and back.
Sadly, we have far fewer of these birds than we should have. Even ten years ago there were reasonable flocks over almost every town and village during the summer months. What have we done, that they no longer come? I wonder if the same is happening throughout their range, which extends as far north as the Arctic Circle and through Asia to China in the east. As long as they have suitable nesting territory and a good supply of insect food they are happy enough, so why should we be losing them?
Some years ago repair work was carried out to the roof of the Galway Mayo Institute of Technology in Castlebar, which had long played host to a number of swift families that had made their homes in cracks and crevices. The repairs worked well for students and staff but did nothing for the birds, most of which soon left. This situation was replicated many times in many towns during the boom years, when we pushed aside our wild things for a mere glimpse of prosperity. As swifts quickly adopt specially constructed nest boxes we could do something to put matters right, for them at least.
Another difficulty could lie with the indiscriminate use of pesticides and herbicides. A dose of poison that might not kill insects immediately will have a cumulative effect on the birds and animals that eat them, including the swifts, damaging reproductive ability and lowering immune systems.
What a remarkable creature the swift is – and how worth looking after. Take a look at its feeding behaviour, for instance. See how the flocks follow the insect swarms, sometimes for hundreds of kilometres in a single day, dining at great heights of a thousand metres or more when they are able or almost at ground level when they must.
If we could fly with them we would see how they feed without swallowing each insect as they catch it, but gather them into a pouch at the back of the throat where they are mixed with saliva and held in a ball called a bolus, to be ingested in their hundreds or even thousands. As their small and inconveniently positioned legs do not allow them to land on the ground they must also drink in flight, which they do by catching raindrops or scooping water with their beaks.
As young swifts grow they begin to look out of the nest, no doubt in anticipation of the next delivery of food. They may spend two or three days loitering at the very entrance until the excitement is just too great. They lean forward that last small bit and that’s it! They are airborne and will stay that way for at least one year and perhaps for three or four, until the time comes for them to raise their own families. So they must eat, drink, sleep, gather nesting material and even mate on the wing.
There is so much more, too, but perhaps we will revisit the swifts when they return. In the meantime there is much to observe in the world of birds.
Wherever there are good numbers of roosting birds there will be hawks and falcons. Along the north Mayo coast young peregrine falcons can be seen in practice flight, dive-bombing the gulls that inhabit the sea cliffs. The last time I was there a pair of juvenile peregrines were tormenting a much larger Greater black-backed gull. I would have stayed to be entertained, but life is so busy. I might fly south, and come back in the spring.