Updates from our Cuckoos

No further signals have been received from Emsworthy's tag since 19 March. He was still alive when we last heard from his tag - but the charge was very low. We may well here from it again after he's crossed the Sahara but it's possible the battery will have degraded too much for that to happen. 

By 16 March, Emsworthy had left Central African Republic and made it to Ghana. He covered 2070km (1285 miles). He continued on into Ivory Coast by the 19 March, joining Ash, Stanley and Livingstone there. 

It looks like a few of our Cuckoos are setting off on their first spring migration movements. Ash and Emsworthy have both joined Stanley in making a move northwards to the Congo rainforest edge while Derek has been in the area for a few days but only transmitting low quality signals, until now, which hadn't registered on the maps. 

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. 

By the 29 December, Emsworthy had moved 190km (120 miles) south-east  to the edge of the freshwater Lake Mai-Ndombe where he has remained since.

Derek and Emsworthy have recently moved westwards and are now south-west of  the Site Lac Tele-Likouala Aux Herbes area. Chris had also been in the area before moving south to Angola, possibly due to dryer conditions in that area this year. 

Six of the tracked cuckoos (Peter, Dudley, Emsworthy, David, Livingstone and Stanley) are already within the Congo rainforest block. The first of these to arrive was Stanley on 16 September, the earliest of the tracked cuckoos ever to arrive there by 12 days! He was followed by Emsworthy on 19 and Livingstone and Dudley on 23. Previous to this year, the earliest Cuckoo had been Chris, who arrived there on 25 September in 2012.

Since then, David arrived on 24 and Peter on 28 September 2014. David was five and four days earlier than in 2012 and 2013 respectively whilst Livingstone was 13 days earlier than last year. It is very interesting to note that all four of the cuckoos who beat the previous earliest arrival date came from northern Cameroon and the adjacent part of Chad, a region that has received over 50mm less rainfall than usual over the past month and more than 100mm less over the past three months.

By the 18 September, Emsworthy had left his location on the border of Nigeria/Cameroon and travelled south-east 640km (400 miles) and was in the Central African Republic (CAR). Since then he has travelled 280km (175 miles) south-west and is on the border between CAR and Cameroon. Poor conditions in the north of Cameroon may have led to him moving on so we hope that he has found better foraging here. 

With most cuckoos now in the Sahel region, we're entering a fairly quiet period in the annual cycle of the tagged cuckoos with less movement than during the migration season.

Birds who completed their desert crossing will spend time in the Sahel recovering their body condition, and some may stay quite a long time. In previous years, cuckoos have stayed in this area for as much as several months, while others spend a shorter amount of time before moving south into the humid zone forests.

The eastern Sahel in Chad and south Sudan has received plenty of rain recently, and thus conditions are likely good for cuckoos. Northern Cameroon was slightly drier than average in August, and so cuckoos such as Derek, Dudley, Stanley, and Emsworthy may be moving on if foraging conditions aren't suitable.