At first it is almost as if I haven’t heard the song at all, the rich trill having to penetrate deep within the layers of memory before it is finally acknowledged and recognised. A series of notes builds and then flourishes with a descending trill to reveal the presence of a male wood warbler, proclaiming ownership of his territory. I am in Wales for the weekend, helping to check the contents of a nest box scheme being operated within a stunning piece of oak and ash woodland that cloaks the deep valley sides. It is a hard wood to work, the ground rough and boulder strewn, the stones thick with moss and slippery with moisture. It would be easy to twist an ankle and I must remember to watch where I place my feet.
This year we are a little late, caught out by a particularly early breeding season that has seen many young pied flycatchers already out of the nest. Those that are still present in the boxes are pretty close to fledging, but still safe enough to ring without the risk of them leaving prematurely. A few of the pairs are on eggs or very young chicks, perhaps late arriving or making a second nesting attempt after the failure of the first.
The presence of the wood warblers is a particular treat. While we won’t be looking for the nests of these ground-nesting relatives of the more familiar chiffchaff and willow warbler, we do set up the nets to catch and ring some of the adult males. Work on wood warblers has become increasingly important as we try to understand why our breeding populations of this summer visitor are in decline. I remember hearing wood warblers as a child in Surrey but the species has been lost from there as a breeding bird, a pattern repeated over much of its former range. It is thought that part of the problem may be changing conditions on its wintering grounds within the humid zone of tropical Africa. Today, however, it is the song that is foremost in my mind. It is delicate, delightful and in perfect harmony with this beautiful woodland. Even the midges cannot lessen the smile on my face.