According to meteorologists, the first day of spring is 1 March. Astronomers would say it’s 20 March. No one in the UK would have believed either date this year, as they battled through wind, snow and ice. Better perhaps to ignore the calendar and look to plants and animals for the first signs of spring: the flowering of daffodils, snowdrops and bluebells, the buzzing of bees, frogspawn in brackish water, the smell of wild garlic, the two-tone call of the Eurasian cuckoo.

The Times used to publish a letter every year from the first reader to report hearing a cuckoo. The traditional date for the first sighting of the cuckoo is 14 April, St Tiburtius’ Day, though in recent years the actual reported date has moved forward a few days. They may be arriving earlier, but fewer of them are coming: according to the British Trust for Ornithology (BTO) their numbers have dropped by 65 per cent since the 1980s. This is probably due in part to habitat loss in the UK, but there may be other reasons too. Cuckoos spend the Northern Hemisphere winter in the forests of the Congo and other parts of West Africa. Since 2011, the BTO has been tracking a number of cuckoos caught and tagged in the UK to study and map their journeys, to learn more about their migration patterns and the dangers they may face en route.

In September 2016 I moved out of London to Manningtree in north Essex, near Dedham Vale. I heard a cuckoo call in these new surroundings for the first time on 28 April 2017, in a hedgerow near Flatford Mill. It brought to mind two things: the first was Delius’s tone poem On Hearing the First Cuckoo of Spring (the clarinet that echoes the cuckoo’s call near the end of the piece has always struck me as rather too slow compared to the real thing). The second was the 13th-century rota ‘Sumer Is Icumen In’:

Sumer is icumen in
Lhude sing cuccu
Groweþ sed
and bloweþ med
and springþ þe wde nu
Sing cuccu

Awe bleteþ after lomb
lhouþ after calue cu
Bulluc sterteþ
bucke uerteþ

murie sing cuccu
Cuccu cuccu
Wel singes þu cuccu
ne swik þu nauer nu

Sing cuccu nu Sing cuccu

The poem says that ‘summer has come in’, but what it describes sounds more like what we would call spring than summer: seeds growing, ewes bleating after their lambs, trees coming into leaf. Benjamin Britten used it for the climax of his Spring Symphony. The rota is a song of celebration, but also of exhortation, a plea – hope against hope – that if the bird stays, the fairer days will stay too: ‘ne swik þu nauer nu’ (never stop now).

After I heard the cuckoo in Essex last year, I looked at the BTO website to see if any of the tagged birds had passed nearby. And, yes, a bird known as ‘PJ’ had been right over the field where I heard the call, at around the right date. I checked the site again recently and saw that PJ had began the journey north once more and was currently in Côte D’Ivoire, probably making his final preparations for the Saharan crossing. There is no guarantee he’ll make it all the way to the UK but I will be keeping tabs on him over the coming weeks and, with luck, somewhere on the Essex/Suffolk border in late April I’ll hear his call.