It’s quite common in August to have what looks like a deserted garden, as far as birds are concerned. The feeders aren’t doing much trade and the trees and bushes are strangely devoid of calls and rustling, the normal signs of bird activity.
Sometimes this causes us to worry that our favourite characters, the missing robin and blackbird, say, have somehow succumbed to disease at the end of the breeding season or have lowered their guard enough to be picked off by the local sparrowhawk or cat.
Usually our fears are unfounded. The garden highways are quiet, true, but that isn’t because of anything sinister. It is simply because the birds are not feeling up to much at this time of year; they are tired and lethargic because they are undergoing their annual moult.
Moulting, the changing of old feathers for new ones, is an important stage in a bird’s annual cycle. Feathers are wonderful things – remarkably strong, extraordinarily light and easy to repair when ruffled – but they are not indestructible.
They wear out, just as our clothes do, and must be replaced, which is the point of the annual moult.
We would be absolutely delighted to have a completely new wardrobe every year (or even twice a year in some cases), but for a bird the process of replacing feathers is energy-consuming and wearing.
It must be a little like adolescence, when all the hapless soul wants to do is to find a private place, lie down and allow petulance to seethe. No wonder birds now spend much of their time low down in the thick foliage, robbed of all their effervescence.
The most interesting of all moulting routines is actually practised by ducks, which, for this month at least, we will consider to be garden birds. If you have ducks in your garden, you might be wondering where all the males have gone, and the answer, in a sense, is undercover.
Wildfowl moult all their flight feathers within a short space of time, which gets things moving even though it robs them, for a short window, of their power of flight.
It seems they are prepared to risk a flightless period for the sake of expedience but not when they are sporting conspicuous male plumage.
So drakes moult into transitional plumage, known as ‘eclipse’, which is almost identical to the appearance of females with their cryptic colour and patterns; they wear this until they can fly again.
With full power restored, they come out as males once more and, dressed in their renewed badge of masculinity, they are raring to indulge in a bit of autumnal courtship.
Another bird that seems to disappear in the month of August is the house sparrow, an absence you are especially likely to notice if you live close to a farming area.
This desertion would seem to be out of character, because sparrows are usually the most sedentary of birds, remaining faithful to their colony and to their colony’s turf for the whole of their lives.
But in August they are seized by a collective tendency to wander to farmland fields and hedges to take advantage of ripening grain and the farmers’ harvest, much as shoppers may be gripped by the fever of high-street sales.
They don’t wander far, but they do wander en masse, and so in the madness of summer, all the local flocks come to feast on the plenty. They will scoff, drink and bicker in a striking parallel with holidaying Britons during an overheated August.
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Some birds really do disappear during this month and for a quite different reason to that of the sparrows. These are the migrants for whom the breeding season has ended and so has the purpose of their stay.
Strangely enough, even while an Indian summer may burn, they depart, slaves to an inbuilt, untrusting internal programme that takes them away from fickle British weather.
The most obvious of these is the swift, an unusual sight by early September, but there are others, too. If you are fortunate enough to have pied flycatchers in your garden they will slip away this month, as will adult cuckoos and certain individuals of a good many familiar migrants. It seems too early for them to leave us.
Swifts often catch a bonus before they go, a golden handshake from British soil. Sometime in August, mating swarms of garden ants will choose a hot, sunny day to emerge seemingly from every corner of every paving stone in the garden, suddenly winged and with an urge to find a mid-air mate.
They lift off and fill the atmosphere in one invertebrate cloud, and the birds go mad, just for one afternoon. Swifts, swallows and martins take it all in their stride, being professional catchers of flying insects, but there are others, too, showing all levels of competence in the air, some good, some hopeless, like hackers on a public golf course.
Sparrows (poor), starlings (competent), black-headed gulls (surprisingly good) and a range of other birds take advantage of this briefest of insect gluts, and watching them can provide a welcome slice of action amid August’s doze.
Ants, though, are not only good for eating. A few garden birds use them for a far more mysterious purpose, putting into practice a behaviour known, with a splendid lack of imagination, as anting.
It involves either picking up some writhing bodies in the bill and applying them to the plumage, or more eccentrically, it may mean sitting on an ants’ nest, or otherwise agitating the insects, and allowing them to run all over the plumage.
When birds use the latter method, they often ruffle all their feathers, spread their wings and tail, open their bill and bask contentedly, as if they were having a massage or a facial.
Anting is one of those things best seen in the garden (you may be fortunate enough to witness a woodpecker doing this), where we can catch up with our birds every day, rather than in the wild, where we would have to be lucky to stumble across a bird in the course of its ‘alternative therapy’.
But what’s it for? There are various theories, but they all veer towards plumage care of one sort or another.
The ants, which respond to being ‘anted’ by angrily squirting formic acid, could perhaps kill parasites on the bird’s feathers or at least cause them to run a mile.
Or perhaps the formic acid itself is some form of insecticide – it is certainly pretty noxious stuff. It could well be both. But how birds came to find out that anting felt good, nobody knows.
If you do see a bird sitting on the lawn or flowerbed with feathers ruffled and wings spread, it might not actually be anting but sunbathing, which is far more commonplace.
Sunbathing is undoubtedly good for a bird. The sun can act on keratin to straighten bent feathers, it can displace parasites that scurry from its heat, making them easier to catch, and it can apparently act on preen-oil to synthesise vitamin D.
So a bird always has a better excuse to bathe in the sun than we do.
And let’s face it, with all the moulting they have to do this month, we shouldn’t begrudge our birds a few minutes of rest and comfort.
