Colours of Wildlife: Jacobin Cuckoo

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Jacobin Cuckoo

Willem is a wildlife artist based in South Africa. He says "My aim is simply to express the beauty and wonder that is in Nature, and to heighten people's appreciation of plants, animals and the wilderness. Not everything I paint is African! Though I've never been there, I'm also fascinated by Asia and I've done paintings of Asian rhinos and birds as well. I may in future do some of European, Australian and American species too. I'm fascinated by wild things from all over the world! I mainly paint in watercolours. . . but actually many media including 'digital' paintings with the computer!"

Jacobin Cuckoo by Willem.

This dapper birdie is a Jacobin Cuckoo, Clamator jacobinus. Its common name refers to its resemblance to monks called Jacobins, who wore black and white habits. The genus name Clamator means 'bawler' or 'noisy declaimer', and refers to these cuckoos' loud calls. Jacobin cuckoos are widespread in sub-Saharan Africa as well as southwestern, southern and southeastern Asia.

A Varied Species

We've a few times had species here that included different forms. The Jacobin cuckoo is one such species. First of all, there are two colour forms: the black-and-white (=pied) one pictured here, and also one that is all black except for white patches on its wings. These two forms are not different species, or even different subspecies – they are just plumage variations similar to brown or blue eyes in humans, and the black and black-and-white plumage forms freely interbreed. Somehow they don't seem to produce intermediate forms.

But these two colour forms are not universal for the Jacobin Cuckoo. They're only found in the southern subspecies. The two northern subspecies apparently only have the black-and-white plumage form. These two subspecies live and breed in Asia and northern and tropical Africa, and come to southern Africa only as non-breeding visitors (though there have been claims of some of them breeding in Namibia and Botswana). The southern subspecies breeds here in Southern Africa, and during our winter moves north to tropical Africa. The further to the south, the more the black form predominates.

Another difference is in the eggs. The two northern subspecies lay bluish-green eggs, while the southern subspecies lays pure white eggs.

New-Year's Birds

In Afrikaans we call this species a 'Nuwejaarsvoël' or 'New Year's Bird'. This is because they arrive in the country close to New Year's. Actually they're often already here in October or even September. Intriguingly, a few may stay here year-round, and even breed outside of their normal seasons.

The call of the Jacobin is, like those of most cuckoos, very characteristic. The main call of the male is a loud triple-call, 'kleu-kleu-kleu', all on the same note. This is often heard at night. Several other kinds of calls are also given, in different situations: contact calls, aggressive calls and alarm calls.

Jacobins live mostly in savannah or scrub country. Like most cuckoos, they are partial to food few other birds will eat – caterpillars with irritating hairs or spikes! Cuckoo stomachs are often found to be thickly lined with these hairs. The caterpillars are easy to find since they target specific host trees; the cuckoos merely have to go to those trees at the right times and will find all the caterpillars they can scoff. They will after catching the caterpillars squeeze them in their bills from one end to the other to get rid of the caterpillars' entrail contents. They do eat some other invertebrates as well, such as flying termites.

When breeding time comes, the male will court the female by a slow display flight, fanning his tail and displaying the white wing and tail feather (in the pied phase) patches. The male gives his courting call, and the female, if interested, will answer. Next, the male will fly off for a while. The female sits quietly and waits for him, but then seems to become impatient and she'll start twitching her wings, raising and lowering her tail, raise her crest and jerk her head from side to side. Then the male returns and she stretches her head forward and lowers her crest. He perches on her back and gives her a gift … a hairy caterpillar with the guts squeezed out! She eats it and he mates with her. Then they both fly off, calling.

Egg Sneaking

A typical cuckoo, this species lays its eggs in the nests of other birds. First of all, the female scopes out the nests of prospective hosts in her territory. Jacobin cuckoos parasitize mainly bulbuls, drongos and fiscal shrikes. The best nest would be of a host that has just laid eggs of her own. Cuckoos have a trick up their sleeve … or more accurately, up their oviducts. The female can retain her egg inside her body for a day or so, during which the embryo already starts to grow. So, when she lays it, it has a head start over the eggs of the host and hatches before they do.

When a suitable nest is chosen, the female cuckoo will perch some distance from it, but where she can keep it in sight. She will sneak in as soon as the host couple has left it alone. If they don't both leave of their own accord, she and her mate will cooperate to distract them. The male will approach the nest making some show, perching prominently and calling. The host birds, seeing the cuckoo, will proceed to chase it; the male cuckoo thus draws them away and then the female slips in and lays her egg. It takes her as little as five to ten seconds. Most of the time she doesn't damage the eggs of her host, or remove one of the eggs as some other cuckoos do. The host eggs sometimes crack when she deposits her egg from a higher perch, letting it drop into the nest. There are occasions recorded where she has cracked at least one of the host eggs and eaten the little embryo inside. But this seems to be rare. Jacobin cuckoo eggs, unlike those of some other cuckoo species, don't at all resemble those of their hosts, but still many host mothers seem to be duped by them, happily hatching and raising the young cuckoos.

Because she doesn't have to hatch her own eggs or take care of her own chicks, the female cuckoo can lay many more eggs per breeding season than most other birds – as many as 25 eggs per season! They take a heavy toll on their hosts: in some regions, as many as a third of all the bulbul nests are parasitized. Some nests even end up with two or more cuckoo eggs (perhaps from different cuckoo females targeting the same nest). Though the female is not as aggressive as other cuckoos in destroying host eggs, and the baby Jacobin cuckoo also doesn't deliberately kill the host's own chicks, it typically happens that the host chicks die when there's a cuckoo chick in the nest as well. But there are cases where the hosts have successfully raised some of their own chicks along with the baby cuckoo.

Jacobin cuckoo chicks have begging calls that sound exactly like those of their hosts' own chicks, but louder, leading them to be fed preferentially. They'll also squat on top of the other chicks, spreading out their stubby wings and preventing the parents from easily reaching and feeding their own chicks.

An interesting ability of the cuckoo chicks is that they have a kind of chemical defense similar to that of mammals like Striped Polecats and honey badgers. They can squirt out a very nastily-smelling fluid from their butts when disturbed! Their normal faeces are produced in little packets that can be easily removed by their foster parents.

The cuckoo chicks grow fast and become bigger than their foster parents before they leave the nests. But they keep begging for food for much longer! And they keep feeding it, even for three weeks after it fledges! Because of the inherent risks of the cuckoo's parasitical lifestyle, not many of the eggs the female cuckoo lays in the season eventually end up as fledged chicks … the fledging rate varies from about one in ten to about one in five.

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