Updates from our Cuckoos

We caught and tagged Cuckoo 'PJ' in the King's Forest, Suffolk, in June 2016, and since then he has provided us with a wealth of valuable data. Through tracking PJ's migrations between UK and Africa, we have discovered that he spends the winter months in north-western Angola. Recently, while en-route to the UK he has spent several weeks feeding up in Ivory Coast and over the last few days we can see that he has tackled the mighty Sahara. He was in, or over, Mauritania on Sunday morning and by 8am yesterday morning (Monday) he had reached Morocco! The most recent update, which arrived at 19:40 last night, showed him in northern Morocco. He is currently in the Middle Atlas Mountains, approximately 95 km (59 miles) south east of Fes. From here, he will move up through Spain and France before crossing into England.

If he makes it back to Suffolk this year, PJ will have completed his fifth tracked migration, which is the most for any Cuckoo that we have tracked so far! It has been a nerve-racking time waiting for PJ to tackle the desert and we'll be keeping everything crossed that the rest of his journey goes smoothly. In previous years, he has successfully completed his desert crossing between 7th and 17th April and arrived back at his breeding grounds in Suffolk between 18th and 30th April, so he is close to his usual schedule.

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.  

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.