Updates from our Cuckoos

The last signals we received from Jake back in June showed that he was still in central France. No further signals have been received since. Looking back, the tag temperature was unusually high during these tranmissions, indicating that Jake had died. We have no idea what the cause of death might have been.

Since we last heard from Jake we have received some good quality signals that show he has moved east. He is currently in central France north of Nevers.

Nine Cuckoos (plus Hennah whose tag has still not sent a good quality location) have now left the UK and seven of these (plus Hennah) are currently in France. The most recent three to have transmitted from France are new Welsh Cuckoo 146760, and Sherwood Cuckoos Jake and Dudley. Jake is currently in Burgundy, while 146760 is further south in the Auvergne region and Dudley is even further south in Toulouse.

It's interesting to note that Dudley left about a week later this year compared to 2014 while Jake left two weeks earlier.

Jake has made it back to England after successfully completeing his Sahara crossing. Ths last good signal we had from Jake's tag was in Benin so we were pleased to see him safely return. 

Jake reappeared in mid-March and was in Benin but it has now been several weeks since we heard anything from his tag. Could he be on the move?

The last signals from Jake's tag were back in mid-January when he was in Congo but recently received signals mean that he is back on the map and all appears to be well. He, like several of the other Cuckoos, has travelled west. His last location was in Benin, close to the border with Togo, in West Africa.   

From time to time we ‘lose’ one or two of our Cuckoos only for them to reappear several days, or even weeks, later. We are never entirely sure why this might be at the individual level but during the course of the project we have noticed similarities between some of the ‘lost’ birds.

We have lost some of our birds just prior to them making a large movement and we think that this might be because they move into denser vegetation in order to feed up before embarking on a long flight. Moving into denser vegetation may mean that the solar panel that recharges the battery for the tag is in shade for periods of time and the battery receives a poorer charge, which in turn results in poorer performance from the satellite tag.

Once the birds have put on enough weight to begin their journey they move into the open and the tag begins charging again and the birds ‘reappear’. We also see the same thing happen, although to a lesser extent, when birds complete a long movement and presumably move into denser vegetation to rest and feed up

There have been a few small movements recently. Fred and Jake have moved west into Congo whilst David has moved into the area that Emsworthy has left. 

These are likely down to changing rainfall conditions which may affect food availability and cause the Cuckoos to seek areas which may be more plentiful in resources. It will be especially important to find a good feeding area before they make any move northwards. There's no consistent direction in which these Cuckoos leave an area and one Cuckoo may move from an area only to be replaced by another moving in from elsewhere, with no obvious reason why.

Fred and Jake, two of our Cuckoos tagged in Sherwood Forest, have moved westwards and are now in Congo. Fred recently left the Mbandaka area and has moved about 270km (165 miles) west from his previous location in Democratic Republic of Congo, while Jake, who is about 70km (45 miles) further south, travelled a shorter distance of 155km (95 miles). 

Interestingly, Derek who is slightly further north, had been moving east, the opposite direction to Jake and Fred, until recently but he has backtracked around 65km (40 miles). Emsworthy has also moved, but northwards to the area not long vacated by Fred. These movements may indicate changing conditions which are encouraging the Cuckoos to seek more favourable areas. 

Jake is still settled in the area of Lake Tumba in the Democratic Republic of Congo.