As recently promised, today’s post is wholly devoted to images of and information about that fascinating species Cuckoo – Cuculus canorus. The photographs are those of a juvenile bird near Nateby on 17th August.
Below is a current summary of the status of the Cuckoo in the UK, reproduced from the British Trust for Ornithology (BTO) website.
“The Common Bird Census (CBC)/Breeding Bird Survey (BBS) trend shows Cuckoo abundance to have been in decline since the early 1980s. The species was moved in 2002 from the green to the amber list, and in the latest review met red-list criteria. The sensitivity of CBC to change in this species may have been relatively low, mainly because Cuckoo territories were typically larger than census plots. The BBS shows a continuing strong decline in England and Wales, but not in Scotland. Cuckoo numbers may have fallen because the populations of some key host species, such as Dunnock and Meadow Pipit have declined. Decreases among certain British moths may have reduced food supplies for returning adults, and the species may also be suffering difficulties on migration or in winter. Strong variation in Cuckoo population trends between habitats may reflect regional differences in the main hosts and differing trends in Cuckoo breeding success among those host species: Cuckoos increased significantly during 1994–2006 in lowland semi-natural grass, heath and bog but decreased in almost all other habitat types. Due to climate-induced earlier breeding in recent decades, Dunnock nests have become less available to Cuckoos and those of Reed Warblers more so: this may explain a concurrent increase in the rate of parasitism of Reed Warbler nests.
The Cuckoo’s habits and parasitic way of rearing its young, so unlike that of any other British bird, is well known and documented so I will not recount it again, but in an old book of mine there is a fascinating account of how the Cuckoo was a puzzle to earlier naturalists. From the days of Aristotle to those of Pliny (AD25 – AD75) the Cuckoo was supposed to undergo a metamorphosis twice a year, appearing during the summer months as a Cuckoo. In “Naturalis Historia” Pliny wrote “a bird of the hawk kind, though destitute of curved talons and hooked beak, and having the bill of a Pigeon; should it chance to appear simultaneously with a Hawk it is devoured, being the sole example of a bird being killed by one of its own kind. In winter it changes into a Merlin, but reappears in spring in its own form, but with an altered voice, lays a single egg in the nest of some other bird, generally a Pigeon, declining to rear its own young because it knows itself to be a common object of hostility among all birds, and that its brood is in consequence unsafe unless it practices a deception. The young Cuckoo being naturally greedy monopolises the food brought to the nest by the foster parents and thus grows fat and sleek, and so excites its dam with admiration of her lovely offspring, that she first neglects her own chicks, then suffers them to be devoured before her eyes, and finally falls victim herself to his voracious appetite”.
So those part time philosopher and naturalist guys without binoculars and field guides were slightly off the mark with their theories about the remarkable Cuckoo, but as we now realise there is a glimmer of truth. We have to remember that in those days no one could comprehend migration or the fact that thousands of miles away in a southerly direction lay hot countries where a Cuckoo could while away the winter months and then return to Europe the following spring.
But it sounds like the birders of that period had certainly weighed up the Cuckoo’s eating habits, its preference for large caterpillars, often the hairy ones rejected by other birds. They locate the caterpillars by perching motionless and often upright on a vantage point from where they scan the surroundings, alert to any movement within yards.
With its peculiar life style a Cuckoo may not be not the most endearing of birds but it is certainly one of the most attractive, and I hope I see one next year, and the year after, and……
Read more about the Cuckoo at the BTO's website here.
