Summer is coming to an end on Dartmoor, and bird migration is in full swing. The swallows are on the move, the swifts are gone, and so are the cuckoos. In fact, adult cuckoos leave the country a lot earlier than previously thought, with most of them gone by early July.
This is one of the discoveries that the cuckoo-tracking project, managed nationally by the British Trust for Ornithology, has made. Even though the cuckoo may be one of our most well-known birds, some of them only spend about 2 months of the year in this country. The rest of the time they are on their way to, or have arrived at, their wintering grounds south of the Sahara.
Earlier in the year, Dartmoor National Park Authority (DNPA) teamed up with Devon Birds (DB) to take part in this national project, and funded the satellite tagging of four Dartmoor cuckoos, who were named Dart, Ryder, Tor and Whortle – good Dartmoor names!
All four cuckoos left the UK in the last week of June. It was at this early stage that their paths diverged: three of the cuckoos flew through western France and into Spain, whilst the remaining cuckoo, Tor, skirted along the French-German border, and then to Sardinia. Prior to the satellite tagging project, it was assumed that all British cuckoos migrated to Africa via Italy; and indeed, this is what the cuckoos tagged in Wales and western Scotland did. However, cuckoos that were tagged in East Anglia in previous years took an entirely unknown migration route via Spain.
Naomi Barker, DNPA ecologist, said: ‘It appears that the Dartmoor’s cuckoos follow both migration strategies, which surprised us, as we had been expecting the Dartmoor birds to behave more like the cuckoos tagged in the west of the UK, rather than like those from the east of England.’
Previous years’ data also shows that the Spanish option is not necessarily a good choice, with none of the birds who chose that route last year completing their migration to Africa. Sadly, this fate also befell two of the Dartmoor cuckoos who chose to fly through Spain: Dart perished on Mallorca; there were reports of forest fires in the area round the time we lost contact, and it is possible he perished in the fire or didn’t find enough food in the dry conditions. Ryder quite simply ran out of fuel on the Sahara crossing, and plummeted into the sand 400km away from his destination.
On the positive side, Tor made a very swift trip to the wintering grounds in Nigeria, flying from near Strasbourg to Nigeria in the space of 5 days; whilst Whortle, a very English cuckoo, having spent 3 weeks between Benidorm and Alicante, made the desert crossing and safely arrived by the Niger on 2 September.
George Harris Chairman of Devon Birds said:”This collaborative project has already thrown up amazing insight into this much loved Devon bird’s journey. Some of the findings are saddening, such as the loss of two of the tracked birds, but that is the reality of this mega migration. We are hopeful the two remaining birds in the project make it back to breed on the moor next spring, by which time we will have surely learnt even more about these fascinating birds”.
We are expecting things to be fairly quiet now during the winter, where the birds recover and rest until they gear up to their migration back to their wintering grounds early next year.