Friday, 27 March 2015

Next Term 2: Cuckoo

Another iconic bird of the spring we will be tracking down next term is the Cuckoo. 40 years ago the distinctive two-note call of the male Cuckoo could be heard in almost any habitat, and the bird could be seen almost anywhere, even in the most suburban of locations. Unfortunately, it has gone into a steep decline since then, and has been lost from many of its traditional haunts. 
Male Cuckoo
Cuckoos have always been much easier to hear than to see, as a poem by Wordsworth attests, and there are many who claim to have never seen a Cuckoo. This isn't something those currently enrolled on the spring course will be able to say. Every class member will be going to at least 2 locations where the Cuckoo is almost guaranteed, and there are a couple of other locations where they are a distinct possibility. 
Last year the Friday groups had a very close encounter with an individual at everyone's favourite North Lincolnshire reserve, plus others were seen at the Turtle Dove location. We also heard them at other venues, but there were several sites where they weren't heard at all, but a few years ago their call would have been a continuous background noise almost every week. 
There is more to the vocal range of the Cuckoo than the 2-note 'song' of the male.  We hope to also hear the unusual bubbling call of the female, and the even less-well known and little-heard 'gowking' belly-laugh of over-excited male birds. 
Some people are struck on their first sighting of a Cuckoo with their resemblance to a bird of prey. The Cuckoo is greyish above and paler below with barred underparts. It has pointed wings, a long grey tail, and bright yellow legs and feet. There is a theory that this resemblance is a evolutionary strategy. Raptors are generally mobbed by smaller birds, so that the small passerines will all gather round the intruder until it gets fed up and moves out of their territory. In a Cuckoo's case a Meadow Pipit, which leaves its nest to mob a Cuckoo will unintentionally reveal its breeding site to the bird which intends to leave its egg in that nest.  
The Cuckoo's unorthodox breeding strategy of leaving its eggs in the care of a surrogate family has worked well for many millennia, but the species has declined dramatically in recent years. Previously, the bird could be found in virtually every habitat type, but now seems to be mainly confined to some wetland habitats, and areas which aren't intensively sprayed with insecticides. For instance, Cuckoos haven't declined as drastically in the wildernesses of some areas of Scotland. One of the main food sources for Cuckoos are hairy caterpillars and other unusual insects, but vast numbers of these have been wiped out since 1970, and the Cuckoo has disappeared as a consequence.
You may read some of the background of the declining Cuckoo and many other species in "Say Goodbye to the Cuckoo" by Michael McCarthy. Of course many Cuckoos have been tracked on their migration to and from the UK in recent years, and you can follow their progress on the BTO migration website.
 Immature Cuckoo

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