The recent news item about an Australian bird, the Regent Honeyeater, forgetting its song because the numbers had dwindled to the extent they could not hear other individuals sing made me think of Rachel Carson’s book which envisaged a time without bird song. That morning, in bed, I had listened to the song of a blackbird, which led to thoughts about the nature of nostalgia.This came to mind later when I walked around Brent Reservoir, the Welsh Harp, (where I had optimistically gone in hope of seeing a Black-necked Grebe). I again felt this sense of nostalgia and tried to pin down the sensations which led to it - the scents of Blackthorn, in full bloom, wild garlic trodden underfoot, an earthy smell of brackish water in the marshy areas, the sounds of coots and moorhens, reminding me of days fishing as a boy, and Great Tits sounding loud now, a robin, and again a blackbird, the sensation of rough willow bark under my fingers, and a slightly simian, atavistic feeling as I used the branches to balance as I picked my way across the sodden ground. Were these the combination of sensations which gave rise to nostalgia, this odd human emotion, which contributes to our sense of time, belying the idea of a tenseless existence, unbidden and therefore unprogarammable. But, whatever, it was then overlaid with a melancholic feeling that it would be tragic if our only experience of birdsong was this faint yearning, and worse, like the canary in a mine, the loss of song in the Regent Honeyeater, it could signal our own extinction.