It’s August, and some of our best known summer-visiting birds have slunk away with
barely a whisper. It’s a far cry from the spring, when arriving birds announced
their presence in full voice, and their sounds were so sure, so dominant, that
it seemed as though they would be here forever. But it turns out that it wasn’t
so. They were just a passing phase, a slogan for a season.
Birdwatchers don’t do departures; we measure our hobby by arrivals instead. In the spring we long to see the first Swallows and hear the first Cuckoo; in the autumn we welcome the winter thrushes, the Redwings and Fieldfares. We are inspired by what is coming in, and try to ignore what we are losing. That’s why we don’t generally record our summer-visiting birds as they disappear southwards. Who knows at what date last year we saw our last Willow Warbler or House Martin? One day they are there; the next they have gone. The last sighting of the year has none of the resonance of the first.
August does seem a little early to be talking about birds returning south. But in fact, this is the month when two or our most iconic species are likely to be seen for the last time; two species, indeed, that are truly notable for the undercover nature of their passing. The Cuckoo and the Nightingale are, in their respective habitats, completely definitive of the explosive height of spring. Once the spring hubbub has died down, though, they fade away to silence and then invisibility. Have you ever seen either in the autumn?
Yet both the Cuckoo and the Nightingale are as interesting for the nature of their
departure as for their boisterous arrival; perhaps more so. Take the Cuckoo, for instance. Once the singing has stopped, and the bringing up of chicks has been outsourced to various small, insectivorous host bird species, the adults have no need to stick around long, and they leave these shores up to a month before their offspring, even at the end of July. Since Cuckoos are thought to migrate directly from Southern Europe to their wintering grounds in sub-Saharan Africa, it is quite possible that some adults arrive there while their young are still dependent on their foster-parents for food, thousands of miles to the north.
What a complete abandonment this is. Brought up in isolation from parents and siblings, and sometimes raised by small birds that don’t migrate at all, the juvenile Cuckoo must prepare for and undertake a journey to tropical Africa driven by nothing but its inner programming. There is nobody to lead or guide. If ever a bird symbolised the essential independence of a bird’s southbound migration, it is this species.
It so happens that we still don’t know exactly where the Common Cuckoo spends the winter, other than in tropical Africa. Until recently, that was also the case for the Nightingale, another bird whose noisy arrival contrasts strongly with its meek disappearance. In the last year, however, scientists from the British Trust for Ornithology (BTO) have tracked an individual from its breeding grounds in Norfolk to its wintering grounds in southern Senegal or Guinea-Bissau, using sensors that detected latitude (by day-length) and longitude (by sunrise and sunset times), so we know where at least one individual goes. But one easily overlooked detail within that story was the timing of the bird’s migration. It had left Britain by the last week of July. It was already well on its way south before our own school holidays framed human perception of the summer season.
Cuckoos and Nightingales are not the only summer visitors to leave surprisingly early. It is time to bid farewell to the Garden Warbler, too, few individuals of which will remain at August’s end. In this species a young bird can be on its migration only a month after hatching from the egg. Most Pied Flycatchers will be off soon and, far more conspicuously, so will Swifts. We see Swifts as quintessential summer birds, but their stay is so brief that it raises a question. Staying here from May to August, can we really call them British birds? And what about first-year Swifts, which travel north with the mature adults but, since they don’t breed at this age, don’t actually touch down for the entire duration of their visit? The truth is that many of these species spend most of their year in Africa, and could be thought of as African birds that happen to spend their brief breeding season with us, attracted by some empty niches and extended daylight.
Therefore, when we are listening to the loud and unforgettable songs of the Nightingale or Cuckoo, and allowing them in our minds to define the spring, it is worth bearing that in mind.