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Tracking the SOS Cuckoos ‘Ash’ and ‘Chester’

The ‘Red Listed’ Cuckoo is one of the UK’s fastest declining migrants, with over 50% of our breeding birds being lost in the last 25 years, with the decline in English birds even greater at 63%. The reason behind these declines is not well understood, but satellite tagging is providing the British Trust for Ornithology (BTO) with vital information about where Cuckoos winter in Africa as well as their migration routes from Africa to the UK and back.

Following the successful tagging of a Cuckoo named ‘Sussex’ in 2013, the SOS worked in partnership with the BTO to sponsor two satellite tagged Cuckoos in 2014. The Cuckoos, which were captured and tagged on Ashdown Forest, were named by pupils from Nutley and High Hurstwood primary schools as ‘Ash’ and ‘Chester’.

Ash was tagged on 29th May and has been named by children at Nutley Primary school Chester was tagged on 5th June and has been named by children at High Hurstwood Primary school


The sad news is that none of the Sussex tagged cuckoos are transmitting any more but between them they have added considerably to the body of knowledge on cuckoo migration. You can read more about their migration journeys below or on the BTO website by clicking here for Ash, or here for Chester.

Summer season and Autumn Migration 2015

Ash arrived back in Sussex on the 25th April, the fourth of the tagged cuckoos to return, and returned to Ashdown Forest having successfully migrated to Africa and back.

Chester was a couple of weeks behind but by 11th May he too was back on Ashdown Forest, the ninth of the cuckoos to return. Sad news followed, however, as no signals were received from him after 4 June and it seems likely he died not far from where he was tagged. It is unusual for a bird to die on the breeding grounds and this could have been a result of the cold wet summer this year. A similar effect was seen in the very wet summer of 2012.

Ash survived the summer and by 17th June was in northern France on his journey back to Africa. Heading south he was east of Lyon by 20th June and the following morning was in Italy just north-west of San Remo. Strangely he then stopped going south and started heading north-east and by the evening of 22 June he had moved 175 miles and was near Bologna. This might have been because the Po watershed and surrounding area, which are used by migrating cuckoos, experienced severe droughts this year. Ash may have been trying to avoid the drought.

From Italy he kept heading north-east and logged a first for British cuckoos by stopping in Slovenia. Previously cuckoos travelling through eastern Europe have travelled through Germany not Italy. From there he turned south again and by 30th June he was in Croatia west of Zagore. It was feared that this area was also suffering from the regional drought and that Ash might not make it. These fears initially seemed realised as a series of poor quality signals were followed by silence and nothing has been heard since.

However, the BTO believe that Ash’s tag failed and that he was alive on the last transmission. So while it is a shame that we are unlikely to get any more data from him, there is hope that he is still alive somewhere and might make it back to Sussex next year.

Spring Migration 2015

After overwintering in the Democratic Republic of Congo, Ash was in Nigeria on the 8th February but by the 9th he was in Ghana, north of Lake Ghana and the Digya National Park. The BTO noted that this was not especially early for Cuckoos to move into the region - in previous years we have seen the first Cuckoos move to West Africa by mid-February. Ash remained in Ghana until 18th February when he moved over the border to Cote D’Ivoire where he stayed for two months until the 20th April. On the 21st he made a big jump to Algeria, then just two days later he was near Nantes in France. On 24th April he was near Cherbourg, then by 25th April his signal showed that he was back on Ashdown Forest, near Wych Cross and very close to where he was tagged in 2014.

Chester appeared to be moving north from Gabon when a signal was received on 5th March, but he had just moved within the country and it was not until 22nd March that his signal showed he had travelled north west to Nigeria, a journey of 460 miles. He appeared to be in the same area until 22nd April, but there was a period of two weeks without a signal, so he may have moved around within the country. There have now been three occasionsl when Chester has appeared to disappear from the map, so his tag may not always charge up fully.

By 22nd April Chester had moved near to Bechar in Algeria, close to Ash's location just a day before. By 27th April Chester was near the Mediterranean coast of Algeria, then on 1st May signals showed that he had moved into Spain, to the Parque Natural Sierra de Maria-Los Velez, an area he had flown over in August 2014 on his migration journey south.


Autumn Migration 2014

After their tagging, both Ash and Chester stayed on Ashdown Forest for a short time. Chester was the first to move south and by 19th June was in north western France. Ash followed a few days later and was also in northern France by 24th June. Although both birds were tagged in the same area of Sussex, their migration routes proved to be quite different.


From northern France, Chester moved almost due south through France, arriving in Spain by 2nd July. By 4th July he was south east of Madrid and stayed there for two weeks before moving slightly further north again. This was perhaps a strategy to find better food sources and he stayed in his adjusted location for three weeks. By 11th August transmissions showed that he had moved south and appeared to be on the southern coast of Spain, and therefore about to take a route through west Africa. This is known to be a riskier route for Cuckoos migrating to Africa. All three of the Cuckoos taking this route in 2012/13 perished, but in 2013/14 five out of six birds survived to reach their wintering grounds.

Signals showed Chester to be in Burkina Faso by 18th August, having left Spain around the 14th August and taken a route through taken a route through Morocco, Algeria, Mauritania and Mali.

Although Chester was further west than the other BTO Cuckoos and had further to travel to get to the Congo rainforest, his position allowed for a much shorter crossing of the Sahara. He remained in Burkina Faso until 21st October when he flew 275 miles south to Ivory Coast. A further signal was received from his tag on 13th November, showing that he had moved into Ghana. He was close to Lake Volta, in a region known to be used by Cuckoos on migration, although more usually when heading north to the UK.

By 17th November Chester had moved again, leaving Ghana and flying over Togo and Benin to Nigeria. He stayed in Nigeria for 14 days, then by 30th November his tag showed that he was further south east near the border with Cameroon. He then travelled another 400 miles to Gabon and by 2 December was finally in the Congo rainforest area.


From his position in the UK, Ash appeared to be heading for Spain, but signals on 4th July showed that he had made a 90 degree turn and flown due east to the northern tip of Corsica. He stayed there for just two days before continuing east to Italy but two days later was moving again, arriving in Croatia by 9th July. After a stay of almost four weeks he took a route directly across the Mediterranean, arriving in Libya by 3rd August and Chad by 4th August.

On 20th September Ash’s signal showed that he had flown south within Chad and was close to the border with the Central African Republic where he remained for a couple of weeks. By 6th October he had moved to the Democratic Republic of Congo where he remained until February of this year.

To find out where the SOS Cuckoos are at any point in time please go to or to follow their individual blogs; click here for Ash, or here for Chester.

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