Cuckoo Tracking Project

Cuckoo. Alan McFadyen

Help us follow Cuckoos on migration and discover why they are in decline.

We’ve lost over half the number of Cuckoos in the UK over the last 20 years.

Since 2011 we’ve been satellite-tracking Cuckoos to find out why. We’ve learned lots of vital information which could help us to understand our Cuckoos -  such as how the different routes taken are linked to declines, and some of the pressures they face whilst on migration. But there is still more to discover. We now need to look more closely at how dependent they are on, and how much their migration is linked, to the drought-busting rains of the weather frontal system known as the Inter Tropical Convergence Zone (ITCZ) as they move out of the Congo rainforest and begin to head back to the UK via West Africa.

Follow our Cuckoos as they move to and from Africa.

This project wouldn't have been possible without the amazing support from funders and sponsorsRead more about the project and find out how you can get involved.

We have been able to share our expertise around tracking Cuckoos with other international studies, such as the Beijing Cuckoo Project.

Skill required

  • Follow our Cuckoos on the map below - use the controls to animate or step through their movements.

Cuckoo movements from 01 May 2020 to 12 April 2021

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Current Cuckoos

Carlton II the Cuckoo Carlton II the Cuckoo

Carlton II

Status: active
Cuckoo 161318 portrait Cuckoo 161318 map marker


Status: active
Valentine the Cuckoo Valentine the Cuckoo


Status: presumed dead

View previously tagged birds

Latest updates

The end of the road for Valentine

19 Mar 2021

Sadly, it looks as if we have heard the last from Valentine. When his tag last transmitted, the battery in his tag was low on charge and had been for some time, but there's also an indication of a problem based on temperature. The temperature sensor in the tag reported about 8 degrees C lower than any of the previous readings in Angola, including those from similar times of day, and we don't think the move north by a few hundred km explains this. We suspect that Valentine perished between the last location in Angola (2nd Feb) and the ones in southwest DRC (16th Feb). Valentine was tagged in June 2019 so we have benefited from a lot of valuable data from Valentine, helping us extend our knowledge and understanding of this amazing species.  

No further news from Carlton II

19 Mar 2021
We've had no further messages from Carlton II's tag since 26 Feb when he was in the forest zone of north eastern Gabon. Although the tag's battery was very low at the time, based on the data collected by the onboard temperature sensor, there's no indication of a problem with the tag. Hopefully we will hear from Carlton II very soon.

PJ still in Ivory Coast

19 Mar 2021

PJ, who is on his fifth tracked annual migration to the UK from Africa, has spent the last couple of weeks in Ivory Coast. The rains are well established in the area that he's stopped off in - in fact, there's been a bit more than expected over the past month (up to 75mm). This should mean there's plenty of food for him. We don't know exactly what he'll be feeding on but expect that this will include some adult insects that have been aestivating over the dry season and have emerged in response to the start of the rains.

The area PJ is in was originally deciduous forest that has been transformed into secondary growth - this transformation might originally have been beneficial for Cuckoos, but depending on the extent of tree loss, it could reduce habitat quality for them. As it's now a few weeks since the rains commenced, it's likely that in addition to emergent insects, there could also be plenty of caterpillars (Cuckoos preferred prey on the breeding grounds) for him to eat by now. He's likely to use this fuel to put on fat amounting to at least 50% of his lean body mass, as well as enlarging his flight muscles, before migrating over the Sahara. He usually spends most of March in Ivory Coast before heading north across the Sahara.

Browse updates from our Cuckoos

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Project timeline, contributions & findings

Project timeline

  • 5/11 - First round of five Cuckoos tagged, wintering sites in the Congo identified 
  • 3/12 - Different routes discovered on return journeys
  • 2016 - First scientific paper published on on the routes of our Cuckoos

Support the project

You can help keep this important project going by either giving a donation, becoming a Cuckoo sponsor, or gifting a sponsorship to someone else. We greatly appreciate the support the project has received, allowing us to continue to monitor this endangered species.

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