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Cuckoo Update

Summer 2021 has been a remarkable summer for Cuckoo. There seem to have been endless widespread records not just of birds calling, but in some instances groups of three and four birds displaying and courting. While numbers of Cuckoo in the UK are in decline that is certainly not the case on Arran.
The first Cuckoos are usually heard in mid-April. This year on Arran it was the 14 April. The earliest record on the island was 8 April in 2017.  Peak migration takes place in late April/early May. Few people are unfamiliar with the song of the Cuckoo, and I am delighted when people take the time to contact me when they first hear the call, but beware Collared Doves can sound similar!

Hearing a Cuckoo is one thing, getting a good view is another. At first glance, a Cuckoo in flight might be mistaken for a bird of prey; they are long-tailed and long-winged and have a fast flight.  If you are lucky enough to get a view of one perched you will see a grey bird about the size of a Collared Dove with a blue grey head, chest, and upper parts; the under parts are white with dark bars; and it has characteristic  long, drooping, wings.  The photograph by Dennis Morrison captures the bird well.  The females have a slight brown tinge across the breast.  More rarely, females occur in a rufous phase. The young are brown barred like these females but with a white spot on the nape.
The well-known feature of Cuckoos is that they lay their eggs in the nests of other species. In Arran, they usually target Meadow Pipits and Dunnocks but over 50 species of host have been recorded in Britain. The young Cuckoo is brought up entirely by foster parents. The Cuckoo parents take no part. It is an astonishing piece of evolutionary behaviour, but perhaps even more mind boggling is to consider that, once raised, the young Cuckoos make their own way to their ancestral wintering grounds in the tropics. No adult guides them. The adults have left weeks before. Not only that, the following spring these young from the previous summer return to northern Europe and are able to recognise and seek out a mate among their own kind. Reflect on that as you listen to the unmistakable sound of the Cuckoo.

Later in the summer, look out for young Cuckoo with their “adopted” parents. The begging response is so strong that often any birds close by will feed it! Please let me know when you last see Cuckoo this summer.

Our knowledge and understanding of Cuckoo migration has been enhanced in the last ten years by the excellent project run by the British Trust for Ornithology (BTO). Since 2011 the BTO has been satellite tracking Cuckoos. The different routes to and from their wintering grounds in Africa as well as the movement within Africa between the Congo rain forest and West Africa are being revealed. It has also begun to shed light on the decline of the Cuckoo population in the UK which has reduced by half in the last twenty years. There is much more information on this outstanding project on the BTO website
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