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JAC is named in loving memory of Professor Jenny Clack, a world-class palaeontologist, widely acknowledged as the leading authority on the evolution of land vertebrates from fish. The name JAC was chosen by Jenny's husband Rob who said "It seemed appropriate I should contribute to this important scientific study of cuckoos in memory of a top-class scientist, whom I adored."

JAC the Cuckoo
Tuesday, June 1, 2021 - 05:00
Tagging Location:
World's End, Llangollen, Denbighshire
Age when found:
Satellite Tag No.:
Wing Length (mm):

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JAC's journey from 01 June 2021 to 21 July 2021

JAC's position on
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JAC's movements

22 Jul 2021 - JAC conquers the Pyrenees

A series of updates from JAC's tag arrived last night showing that by 19:33 he had flown 672Km (418 miles) south from his last location near Maintenon, France, over the border into Spain. He was on the slopes of the Sierra de Manga mountain range, close to the village of Ainet de Besan. He was approximately 8Km north east of the town of Llavorsi. Subsequent, low quality signals showed him pressing on further and by 23:25 last night he was 25Km north west of Barcelona. Will he carry on to Africa from here, or stop for a rest? Stay tuned to find out. 

29 Jun 2021 - JAC moves south

Since crossing the Channel JAC has flown a further 133 km (83 miles) south east and has spent the last few days around Maintenon, approximately 64km south west of Paris. 

25 Jun 2021 - JAC makes it to France

Having spent a few days near Barnard's Green in Worcestershire, JAC has flown 340 km (211 miles) south-east across the English Channel, arriving in Normandy yesterday morning. He is close to Saint-Nicolas-de-la-Taille.

17 Jun 2021 - Introducing JAC

Top BTO tagger Lee Barber arrived to find BTO Cymru colleague Kelvin Jones already on site, with the nets up and a recently caught Meadow Pipit and female Sparrowhawk ready to ring. Once these had been processed they switched their Cuckoo tape on and this generated instant interest from a nearby Cuckoo. After a few passes, JAC was in the net. JAC is still near his tagging location north of Llangollen.

17 Jun 2021 - Meet the 2021 Cuckoos

After being unable to tag any Cuckoos in 2020 due to COVID-19 restrictions, we are delighted to be able to introduce eleven new Cuckoos this year!

The tagging teams faced some very early starts as usual to tag the Cuckoos, but they were rewarded with birds who were interested enough in the female lure to be caught, weighed and tagged (with the exception of a location near Loch Katrine where there were a number of female Cuckoos around, making our lure less convincing!).

Some of these newly-tagged birds have already begun their migration south, with one in France, one in the Netherlands and one of the Scottish birds is already down in Essex.

Keep an eye on the individual birds' blogs for updates on their progress.

Past updates from Jac

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Information on this page is for illustrative purposes only and should not be reproduced without permission
© British Trust for Ornithology.