Friday 18th May was a particularly exciting day for me, as Chris Hewson and Lee Barber from the British Trust for Ornithology (BTO) were visiting us for a very special reason...
The BTO have been studying the migration of cuckoos since 2011, fitting the larger male cuckoos with satellite tags to learn if their different migration routes can be linked to the decline in cuckoo numbers in the UK over the last 20 years. They have seen declines in Scotland and Wales, but the greatest has been in England: 68% decline in 25 years.
We're delighted, therefore, that at Knepp Wildland we are surrounded by that unmistakable call in the spring; we think their good numbers here may be linked to the abundance of dunnocks nesting in the heavy scrub and growing-out hedgerows as this is one of the species that the cuckoo will parasitise the nest of. It's tricky to estimate but we think we have six males that frequent the Wildland.
It was 04:15 and just getting light when we met - we had set up the kit the night before so we were ready to go at dawn. We unravelled the nets, set the cuckoo sound lure going and put the pièce de résistance in place: Madame Cuckoo, the cheeky temptress.
Within minutes there were two excited male cuckoos in the net! I was amazed at how quickly they responded. We were able to put BTO metal rings on each bird (each ring has a unique number), measure and weigh them, and then fit the satellite tags. It was fascinating watching Chris and Lee fitting such an intricate bit of kit to these cuckoos, knowing that the data that the tags would collect and regularly feed back could be crucial to help the conservation of this species.
The satellite tags amazingly weigh less that 5g (that's the same as a sheet of A4 paper) - this allows birds as light as 100g to be tracked. The tag has a solar panel that allows a smaller battery to constantly recharge.
Since these cuckoos were tagged back in May they, along with nine other cuckoos, have undertaken the most amazing journey south to central Africa. Forty two cuckoos have previously been followed by the BTO on this journey and from this research it has been discovered that cuckoos take one of two routes: southwest via Spain and Morocco (the ‘west route’) or southeast via Italy or the Balkans (the ‘east route’) before converging in the Congo basin of central Africa. Birds taking the west route are more likely to die before completing the Sahara crossing (more details about this on the BTO website) so imagine our horror, then, when we see that all three Knepp birds are heading off on the west route!
There were a few hairy moments for us as we waited for news of their progress - but we were so pleased to see yesterday that Raymond had made is safely across the desert - he was the last of this year's cuckoo cohort to make it across...Phew!
Knepp has settled in Burkina Faso, joining four other tagged cuckoos.
Raymond is currently on the eastern edge of the Reserve de Faune du Ferlo Nord in Senegal.
Lambert is in Senegal and the BTO say "He is the furthest west we have seen any of our cuckoos."
Amazingly all the BTO tagged cuckoos have survived their perilous Sahara crossing. Now we anxiously wait to see if they survive the season in Africa and if Knepp, Raymond and Lambert make it back all the way to Sussex next spring….
Do keep track of the BTO cuckoos on their website; any donations towards this research is most welcome by the BTO. A sustainable solar company Sussex Solar, based close to Knepp Wildland, has very generously sponsored 'Knepp' the cuckoo and are coming on safari in spring 2019 to enjoy the call that we're already looking forward to hearing again.
Many thanks go to Chris and Lee from the BTO, and to the 'Cuckoo King' Tony Davis for making this happen.
by Penny Green, Knepp Ecologist