Through the open window came what my sleep-befuddled mind took to be the song of a willow warbler. A couple of prolonged and surprising notes, pure as those of a nightingale, were thrown into the mix and grasped my attention. Glimpses of restless rusty carmine from among lemon-inflected hues of the new oak leaves revealed the presence of one of the best mimics and loveliest of our summer visitors. The cock redstart was back, and singing for a mate.

Within the week she arrived, silent, more subdued in her plumage but still with a bright bobbing flash of russet tail as she sought out a habitual nesting hole in the dry-stone wall of the barn and busied herself to and fro with moss plucked from field dykes, wool shed by the ewes. Great tits and pied flycatchers vied noisily for nesting boxes in a high ash tree. The hen redstart merely carried on with ceaseless gathering activity, the cock chorusing her along with little bursts of song. They nest early in the Welsh hills, hatch their broods and are away south for Africa before August arrives.

I love the brief season they spend with us, am always sent back to compare notes with John Buxton's 1950 monograph, The Redstart, published from observations made during the years that the Oxford literature don spent in Bavarian PoW camps between 1940 and 1945. The exact and scrupulous observation of "his" birds, for the most part tolerated by his captors, is a model of what writing on nature should be: authentic, personally knowledgable, scientifically rigorous, wondering, patient.

Redstarts were his freedom, living "only in the moment, without foresight and with memory only of things of immediate practical concern to them". He could scarcely have found a happier subject than this amiable, elusive, sweet-voiced and beautiful little thrush.