Before even the first migrant arrived a handful of our resident birds would have started breeding. The raven would be sitting on her eggs high in her lofty cedar, but at the opposite end of the spectrum of birds, the long-tailed tits would not be far behind her, the feeding parties of winter long since having broken up. On the day the curlews arrived, I found two of the tits’ distinctive nests, one on the riverbank and one on the old railway track, already fully built though not yet lined. Both were in dense gorse bushes, their preferred nesting place for the protection it gives them from predators. All tits are hole-nesters, but long-tailed tits are misnamed — they are not really tits at all — and build the most elaborate and beautiful nests of any of our birds. A perfect egg-shaped ball of moss and lichen, knitted together with cobwebs and lined with up to two thousand feathers. It is a time-consuming business building a nest like this, the birds fly back and forth constantly in a fever of activity, and it’s no wonder they have to start so early. The nest seems tiny, it’s hard to imagine that a single bird with such a long tail could fit in there, let alone a whole brood, but they do.
The day after the curlews came, the showers began, building to a steady, relentless downpour that seemed as if it would never let up. The following day I walked to the river to find the water level had risen by seven or eight feet overnight and the long-tailed tits’ gorse bush was now a green island draped with flotsam. The water never quite reached the nest but it was too late, it was abandoned anyway, before it had even been lined. The nest on the railway track was a success though, the entire brood fledged, and when the season was over curiosity got the better of me and I took the nest home to dissect. The birds had done a good job of keeping it clean; they were fastidious parents. This nest was lined with around twelve hundred feathers. There was not as much variety as I might have hoped for; the nest was located near to some pheasant-rearing pens and over eighty per cent of the lining was pheasant fea-thers. But there were at least sixty tawny owl feathers too, presumably from a nearby old nesting hole, and significant numbers from blackbirds, woodpigeons and curlews. It took me all afternoon to pick through and sort them, and then I laughed at myself and wondered if I had too much time on my hands.
When the breeding season began in earnest, I got to work on a weekly check of the hundred and twenty nest boxes I looked after, scattered through a sprawling trail of woods down in the foothills. It would take the whole day to visit them all. There were a couple of small alder woods on the way, and one mature mixed oak wood dotted with beeches and pines, but mostly they were hanging oak woods. These are the classic woodlands of Wales, positioned on steep rocky hillsides with the trees’ trunks twisted and contorted from the elements and fighting their way through the boulders. Given the chance this woodland would cover the whole land, as it once did long ago, and the hanging, twisted woods that remain are simply the fragments that have been left untouched because they are in spots unsuitable for cultivation, too steep or too rocky or both. They have their own unique atmosphere, these hillside woods with their thick ground layer but little understorey, and there are a handful of birds that are most at home in these woods, who live here in population densities unmatched anywhere else: the wood warblers, the pied flycatchers, the redstarts. You step into the green light that filters through the canopy and are assailed by bird calls: the chinking of chaffinches and great tits; the gentle cascade of the willow warblers; and the trilling song of the wood warblers that is the defining sound of these woods, along with their call, a kind of gentle whoop that wouldn’t sound out of place in a jungle. I don’t like phonetic renderings of birdsongs, they never seem to me to do the bird justice; birds simply don’t use our alphabet, they need one all of their own.
These woods felt totally wild; they were trackless and I never met anyone else while I was walking through them searching for the boxes one by one. I came every week for over two months, and recorded on nest-record cards the different stages of nest-building, laying dates and when the mother bird began to sit, hatching dates, the development of the young and when they fledged. I didn’t keep these records only for the birds in the boxes but for any other nests I found too on my way through the woods: the robins and warblers that hid their nests in the ground layer among the bluebells; the thrushes in the hedgerows along the way; the goldcrests’ tiny mossy nests suspended from the branches of a conifer; the stock doves and the buzzards deep in the woods. I have a knack for finding nests, but I’m not sure it is something I could teach; it’s as if you have to think like a bird, you have to try to imagine the place that you would choose were you that bird. You have to get to know the individual preferences of different species. As you watch them from a distance, where is their attention focused? And, as you approach closer, where does their anxiety emanate from? My observations of individual birds meant the most to me personally, but these were not scientific. An incident of dramatic behaviour I had seen could well have been anomalous. Scientific validity comes from the slow accretion of small facts. It is the analysis of tens of thousands of nesting records that will reveal a population slump or a change in the distribution of a species. So this was me paying my dues.
My nesting boxes would all be in use, every last one, unless perhaps one had lost its lid during the winter. Over half of them would be occupied by pied flycatchers, stocky, handsome little birds, the male black and white, the female brown and white. They are uncommon elsewhere but in these oak woods they are the most numerous species. Their population seems to be limited not so much by the supply of food as by the availability of suitable nesting holes, so if you fill a wood with nest boxes you can double the local population. Although it is not a common bird, not even a familiar bird to those who live elsewhere, it is one of the most intensively studied of all British birds. There are two main reasons for this: the first is simply because they take so readily to nest boxes; the second is that they sit so tight. It is possible to lift the sitting bird off her eggs, check the nest, and replace her as she was. The birds seem completely unfazed by this level of intrusion, though the male may come and hop around you, calling in annoyance while you are there. A significant number of the sitting females would have been ringed in these same woods as infants, so I took down the numbers and sent them off for the record. It was all grist to the mill.