08/08/2012
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Lyster crosses the Sahara

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On the afternoon of 29th July, Lyster was still transmitting from Catalonia, approximately 130 km (80 miles) west of Barcelona. At around 3am on the morning of 1st August we received an unconfirmed location that placed him travelling south over the Balearic Sea, and a matter of hours later a signal showed that he had made landfall in Algeria. This last transmission placed him right on the coast close to Sidi Ghiles, a town in Tipaza Province in northern Algeria. He had travelled around 570 km (350 miles). Locations do not reveal whether he crossed straight from his position near Barcelona or whether he travelled south through Spain to minimise the sea crossing, or possibly even rested briefly on one of the Balearic Islands as he crossed over.

Last year Lyster made the crossing much further west, when he headed across the Strait of Gibraltar and then on to Casablanca before skirting around the western end of the Sahara and heading south to Senegal. It was expected that he would follow the same route this year but, instead of a short 10 km hop across the Mediterranean, he took a 500 km sea crossing 1,000 km further east than last year. Lyster's southbound route this autumn lies close to his northbound route from this spring; perhaps he found the habitat in northern Algeria to his liking and altered his route this autumn to take advantage of suitable habitat — or perhaps he simply drifted off course. Locations received on Friday 3rd August and early on 6th August show that he has headed southwest out of Algeria, cutting across the corner of Mali and into Mauritania. He looks as if he is heading towards Senegal, where he also spent some time last year on his southward migration.


Lyster's last 365 days of movements. The right-hand line shows his movements south in 2011 while the left-hand line shows his return route this spring; the central line shows his southerly route in 2012, culminating in his current position in Mauritania. (Data: BTO/Map ┬ęGoogle).

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Meanwhile, Idemili — who was taken to the Wildlife Aid hospital in Leatherhead — has been making good progress. Staff at both BTO and Wildlife Aid are elated with how far she has come: she has put on weight and has now reached 116g, almost 60% heavier than when she was brought in! She has completed the regrowing of her missing wing feathers and has approximately 5 cm left to grow on her tail. Her eye has not fully recovered and the vet who examined her has told Wildlife Aid that she has a damaged pupil and that she does not have 100% vision in that eye. However, she is perfectly able to pick caterpillars from leaves in her outdoor aviary so will be able to find food for herself. Wildlife Aid have done a fantastic job of rehabilitating her, which has meant that we have had to start thinking about her release.

We were able to follow her movements for a month or so when she was in Wales before moving to Surrey. The terrible weather in Wales will have made it difficult for her to find food and no doubt contributed to the state she was found in after being attacked by other birds. She is now heavier than she was when she was first tagged; however, she will need to readjust to finding her own food, coping with the conditions in the real world and the physically challenging demands of migration. Adult Cuckoos are rarely found in the UK in August and most of our tagged males are now either staging in areas to the south of Switzerland or have crossed the Sahara. While a few females may still be in the UK and won't have embarked on migration yet, Idemili was obviously ready to set off and is now quite far behind schedule.


Idemili gets weighed (Wildlife Aid Foundation).

Now that she is back to health we have had to consider whether it is both scientifically and ethically right to reattach the tag to a rehabilitated bird who has already been through such a tough time, and has yet to make it to Africa and the crossing of the Sahara Desert. While it would be very interesting to be able to track a rehabilitated bird, both for science and to gather information for those who invest time in the rehabilitation of individuals, we felt this was inappropriate. Whether she is translocated to staging areas in southern Europe (or straight to Africa) by Wildlife Aid or not, Idemili's unusual few months and the fact that her journey has been delayed while she recovers will no doubt affect the validity of the science that we gather from tracking her. Would the experience affect what she does in the coming months or would it be typical of female Cuckoos? With all these factors in mind, we have decided that she will not be tagged. We are disappointed that we were only able to track such a small part of her journey and that we will not be able to track her further, as we are sure many Cuckoo sponsors and supporters will also be, but we have to put Idemili's welfare first and give her the best start in what will be a long journey to her winter destination.

Written by: BTO