The recent rains at Londolozi have provided much needed respite from the dry season. As the rain nourishes the earth, the trees draw that moisture up through their roots and their bright green leaves add a new vibrancy to the landscape. This knock-on effect continues; as soon the leaves appear on the trees, invertebrates emerge from their winter slumbers to feed on the fresh plant growth. Insects like moths, grasshoppers and butterflies become regular features around camp – if you look out for them. The result of the sudden increase in insects is that many bird species that spent the winter months elsewhere in the world return to Londolozi to feast on the abundance of food. One particularly fascinating family of birds that return in time with the first summer rains is the cuckoos.
Most of the cuckoos that are found at Londolozi are migrants that fly in from north and central Africa close to the equator in order to capitalise on the sudden increase of insect life, most notably caterpillars. Caterpillars hatch from eggs laid by butterflies and moths and will need to go through a four-stage metamorphic life-cycle before they can undergo metamorphosis, turn into their adult winged forms, and the cycle repeats. Caterpillars make up the vast majority of the cuckoos’ diet. The Jacobin cuckoo, for example, likes hairy caterpillars like those of the Processionary Moth (Anaphe reticulate) larvae whereas the African cuckoo is less selective and will eat hairy and smooth caterpillars alike.
While the cuckoos arrive in South Africa primarily to make the most of the abundance of food at this time of year, they also arrive for another reason – to breed.
With the exception of the Common cuckoo, all the other cuckoos at Londolozi will breed here during the summer months. When compared to the majority of other birds, the breeding strategy of cuckoos is unconventional to say the least.
Cuckoos play absolutely no role in raising their young; what they do instead, is get other birds to incubate and raise their chicks for them, a behaviour known as brood parasitism. A red-chested cuckoo, for example, will attempt to lay its eggs in the nest of an unsuspecting white-throated robin-chat. The robin-chat will try to chase the cuckoo away but all the cuckoo needs is a few seconds to lay its egg amongst the eggs of the robin-chat.
After the deed is done, the cuckoo leaves and the robin-chat will incubate the cuckoo’s egg as if it were her own. The cuckoos are so amazingly adept at parasitizing the nests of other birds that their eggs even look similar to the eggs of the host bird. In some cases the female cuckoo will evict the eggs of the host’s nest, as in the case of the African emerald cuckoo. In other cases, the female will simply lay her eggs next to the host’s eggs and allow the host to incubate the eggs. Sometimes the host will notice that the egg isn’t hers and will reject it, but often the host is completely unaware of the trickery. While some of the cuckoo species will be reared alongside the host’s chicks, some cuckoos, like the chicks of a Klaas’s cuckoo, will hatch early and remove the other eggs or chicks from the nest. Amazingly, even in these instances, the host parents will still treat the cuckoo as their own offspring by bringing them food and protecting them.
Have a look at this amazing footage taken at Londolozi a few years ago, of a young Great Spotted Cuckoo being fed by its host parent, a Burchell’s starling.
As if the breeding habits of cuckoos weren’t bizarre enough, things become even more unbelievable when the young cuckoos leave the nest. The cuckoos almost instinctively know how to act like cuckoos despite the fact that they are raised by birds of a completely different species. Case in point: the Levaillant’s cuckoo will most often be raised together with the chicks of arrow-marked babblers and will learn the call that the babbler chicks use when begging for food. The babblers feed their chicks mainly insects and relatively few caterpillars, however, the Levaillant’s cuckoo will leave the nest and selectively feed on caterpillars instead of other insects – all based on instinct. The same Levaillant’s cuckoo will forget the call of the begging babbler chicks and be able to give off a pitch perfect Levaillant’s cuckoo call without ever being taught. Further still, all these freshly born cuckoos that belong to species that migrate during our winter months know exactly what time of year to leave Londolozi and which specific route to take without any guidance from other cuckoos. It is unfathomable how they know what to do, yet nature has a way of amazing us in so many different ways.
When summer eventually gives way to autumn it takes with it the green leaves, the many caterpillars and the cuckoos but rest assured the cuckoos will return, like they always do, and the curious case of the cuckoos will again be reopened.