The common cuckoo. Picture by Gabriel Buissart.
NATURE NOTESEveryone knows the cuckoo —or do they?
Certainly it is likely everyone thinks they know what a cuckoo sounds like, but I suspect few people would recognise the bubbling call of a female cuckoo, and they might even be surprised by the less familiar noise of a cuckoo 'gowking’.
The Eurasion or grey cuckoo is a secretive bird, more often heard than seen, and remains the subject of speculation about some of its habits.
Even the mechanism of its familiar call is a the topic of debate: while some observers note it seems to call with its beak closed, Conor Jameson, in the most recent issue of Birds (the RSPB member magazine) suggests that the birds may call on both an 'in-breath’ and an 'out-breath’. He wonders if this might be the reason for the change in pitch between the two parts of the 'cuck-coo’ call.
If you are lucky enough to have seen a cuckoo, you may have noticed it bears a superficial resemblance to a bird of prey. This similarity convinced our forbears that the bird, so audible in summer, turned into a kestrel in the winter.
Of course, the secrets of migration were not known to them, and this must have seemed like a logical explanation for its disappearance for much of the year.
The cuckoo is the stuff of myths and legends but the lifestyle of this parasitic bird is almost stranger than fiction.
It arrives in Britain, usually some time in April, from the southern half of Africa — an occurrence often reported in the pages of our most august newspapers by enthusiastic correspondents.
The adults waste no time in getting down to the business of breeding, the males having an extraordinary repertoire of bobbing and twirling movements in addition to their sometimes frantic calling, especially when competition for females is high.
The females, meanwhile, are spying on their prospective foster parents to find out where they are nesting.
In northern areas, the most common hosts for cuckoos are meadow pipits, but here in the south dunnocks (or hedge sparrows), robins, and other common hedge-row birds are frequent unwitting foster parents. Nevertheless, cuckoos’ eggs have been found in the nests of more than 50 different birds in Britain. So how do they get away with it? Evolution would tend to suggest that host species would get wise and get clever, and some species have indeed developed strategies — not particularly good ones, however.
Instead of heaving out the rogue egg in the nest, quite obvious because of its size, they will abandon their nest and start again.
Black caps and spotted flycatchers have apparently adopted this technique. This may prevent the hatching of a cuckoo egg but it also demands more energy from the potential host, who has to build another nest and lay another clutch, equally at risk from being infiltrated.
Nature, having assured the cuckoo egg is likely to be the first to hatch, then permits the imposter to empty the nest of its legitimate rivals, manoeuvring the eggs (or other hatchlings) onto its back and hoisting them over the side.
The parent birds make no attempt to prevent this or to rescue their doomed offspring, seemingly accepting their fate. For the rest of the summer they are at the beck and call of the huge monster, which appears to be insatiable.
Adult cuckoos, having wreaked their havoc, skip off back to Africa in late July when their erstwhile offspring are still being fed.
The youngsters are left to make their own way back to their winter quarters, apparently by instinct.
An example of how not to bring your children up as their subsequent behaviour is, of course, no better than that of their parents!
If you have access to the internet, a couple of links for you to try: to see some good footage of cuckoos, watch this clip from Springwatch, www.bbc.co.uk/programmes/p0084rqs