Letter: Further theories on cuckoo decline

IT MUST be a source of great satisfaction that we now know the destination of the Norfolk cuckoo in the northern winter, and indeed the routes taken to get there from Norfolk (News, 6 May). (In my latest book, Walter’s Wiggles: The Random Thoughts Of A Random Traveller, there is some useful speculation as to why the five known routes should differ.)

A good answer leads to more questions and two of these need to be answered.

Has the crash in the numbers of the British cuckoo been replicated in the other countries of northern Europe, Denmark, Germany, Sweden, etc? Could the decline of the cuckoo be associated with a decline in the numbers of its hosts – the reed warbler in Norfolk or the sedge warbler in Wester Ross? A shortage of suitable hosts would presumably result in fewer breeding opportunities for the cuckoo.

Walter M Stephen, Edinburgh