Updates from our Cuckoos

It looks likely that BB, Peter, Skinner, Waller and Whortle have failed to complete their migration this year, or their tags are no longer transmitting, and so we will be moving all of them to the inactive section of the website.

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

Several of our Cuckoo tags have not sent transmissions for over 10 days; BB, Hennah, Peter, Skinner and Waller. 

This means they are not currently shown on the main map by default, although can be switched on using the tick boxes under their photos. It's not uncommon for Cuckoos to disappear for up to several months during mid-winter as tag charging conditions in the forest are poor so we won't really know their fate unless we receive further transmissions. If they fail to move northwards when expected then either the Cuckoo may have died or the tag may failed or degraded. Our greatest concerns are still for Peter and Waller who were in the same area when signals were last received, all the way back in October.

Signals on 22 November show BB has moved a little further south-east and is now close to the border with Congo.

BB has travelled south and is now in the Congo rainforest. He has moved over 840km (520 miles) from his last location in Chad and is now in the south-east of Cameroon.  Despite being so much later than many of our other Cuckoos, he is in fact earlier than last year, when he moved to the rainforest on 9 December, travelling slightly further south and into Congo itself. 

Signals received on 13 September show BB had continued across the desert and was in Chad, roughly 380 miles north-east of Chris, who was settled around Lake Chad after completing his desert crossing.  A further signal on 15 September shows that BB had travelled 105km (65 miles) south-east. This new position means he still has roughly the same distance to travel again before he is on the same latitude as Whortle, the most northerly of the other Cuckoos

Chris is finally on his way over to Africa but BB is still in Italy.  Although 'late' like Chris, signals indicate he is still alive and so we hope that eventually they will both successfully cross the Sahara. It's really interesting that these older birds, Chris, who was tagged in 2011, and BB, who was tagged in 2012, have changed their schedules this year to leave so much later. Is age proving a factor in being able to put on enough fat to to make the tough journey?  

This year, because there are so many Cuckoos and routes to view on the map, individual birds only show by default if there has been a signal in the last 10 days.

Currently Gowk, Gilbert, Meavy, Waller and BB have all stopped being shown by default as we haven't heard from them in this period. Don't worry, it doesn't necessarily mean anything bad has happened. There are often periods where the Cuckoos are in dense undergrowth, where the tags don't receive enough light to charge or send signals to the satellites, often just before and after big movements.

You can still view these Cuckoos on the map by ticking the box underneath their pictures. Once we receive a signal, they will automatically reappear on the main map. 

We are still following twenty-two birds. Currently two cuckoos are in France – Walpole and unnamed cuckoo 134957.

Five birds are in and around the Po Valley in northern Italy – BB, Chris, Stanley, Waller and Livingstone.

Six birds are in Spain – Two of these are big movers this week. After finally leaving the UK, Derek hasn’t hung around. After a brief stop in central-western France, he is now in central-northern Spain, just south of Tolbanos de Abajo. It is Maji that has provided the biggest surprise though. He seems to be taking a tour of the European mountain ranges. Having spent a time in the Austrian Alps, he is now in the central Pyrenees!

David is still in Montenegro and Ash is still in Croatia; both of these birds could make the move to Africa any day now.

We now have seven birds in Africa, six of them south of the Sahara. Emsworthy is the latest to arrive here and he is currently just south of Lake Chad, in an area that Chris also favours. Three other Cuckoos – Peter, Hennah and Dudley – are also close to Lake Chad.