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.