No two years are the same for migrating cuckoos, or so it seems. Last year I wrote about five cuckoos, tagged in England, who wintered in the Democratic Republic of Congo. Two took a westerly route through Spain, the rest headed towards Italy, but all survived the journey south. It was on the return journey to their breeding grounds that three of the five presumably perished. This year two more birds were tagged in England, but only one has reached the Congo basin. One of last year's tagged birds, he roughly retraced his route through Italy and Chad. The other three birds took more westerly flight paths. One made it through Spain as far as Mauritania; another, whose movements were very erratic reached the south of Spain. This year that country endured a torrid summer and there were outbreaks of wild fires. It is thought these may have destroyed the food plants of the caterpillars on which cuckoos depend, and the three birds, now presumed dead, had insufficient resources to fuel their flight.
This year five cuckoos were tagged in Wales. The only female among them became a victim of a predator before she left Britain. Two of the remaining birds have successfully crossed the Sahara. One of these, aborting his first attempt to cross the Mediterranean, had almost reached the coast of Libya when he must have intuited he had not built up sufficient body to allow him to continue his journey. After a round trip of 3000 Km he returned to Northern Italy and spent weeks there before undertaking a successful flight south. A third male bird is still in the Po watershed in Italy, a favoured feeding ground among cuckoos, having spent some time zigzagging over southern Europe. The only individual tagged in Wales, who is currently giving cause for concern, reached Libya before his tag stopped transmitting. All of the birds from Wales headed south-east. One even went as far east as the Balkans.
Five canny, or perhaps just lucky, cuckoos were tagged in Scotland. All five headed south-east (one was detected in Montenegro) and all five crossed the Sahara, although the tag on one has not been transmitting recently.
The overall impression is that 2012 has been a much tougher year for migrating cuckoos. Of the thirteen male birds tagged, there is evidence that only eight are still alive. Perhaps they will find respite in the Congo before starting the long journey north in early 2013.
