Gareth Huw Davies

Everything else

It’s well into May and we are still waiting for the cuckoo

So where’s the cuckoo? For the third successive year, I haven’t heard it call in the fields around where I live in rural southern England.

That is after hearing it, without fail, every spring for more than 20 years. There is still the outside chance that the bird may yet arrive, but it really is very late.  (I wrote this earlier this year.)

It will still be several years before we know for sure what is going on with the cuckoos that visit and breed in the UK in the summer. I hope that, by the time we know the reason, or reasons, it will not be too late to reverse its decline.

In 2009 the bird’s status was listed as critical in a database compiled in the database Birds of Conservation Concern 3, compiled by a partnership of organisations, including the British Trust for Ornithology (BTO), Natural England and the RSPB.

Since the early 1980s cuckoo numbers have dropped by 65%. The RSPB’s website puts the current population at around 15,000 pairs, although that figure might be slightly optimistic.

Since 2011 the BTO has been monitoring the movements of five cuckoos, which it fitted with location devices.  The organisation wants to find out more about their stop-over sites and wintering destinations on the way to and from Africa to give it some idea why populations in the UK were suffering. It has since expanded the project to include further birds.

Possible causes for the decline include predation in Africa in their wintering grounds, which seem to be mainly in and around the Congo rainforest, climate change and the use of pesticides.

One plausible explanation, although it remains only a theory, is that a string of early springs in the UK is knocking its breeding timetable out of kilter. The birds in whose nests it lays its eggs have been nesting earlier, sometimes by several weeks when the weather is sufficiently benign.

The cuckoo, unaware that spring has arrived early in the UK, stays on in Africa, travelling back at its customary time, too late to find nests still with eggs in them.

I find this theory plausible, although we will need proper scientific analysis to substantiate it. The days are gone when you could walk into the fields around where I live and talk to a man working on the land who could tell you about the birds he’s seen and heard.

Is it yet more more evidence that climate change is affecting our lives in so many ways? We need to know soon, while there is still time to do something about it.

Some of the best advice and guidance is likely to come from the BTO, who know more about the cuckoo’s movements, both in the UK and on its long migration routes to central Africa, than anybody else.