They may have a bad rap in literature (One Flew Over the Cuckoo’s Nest and The Midwich Cuckoos for example) but there are few more fascinating birds than cuckoos. In Southern Africa, cuckoos are all migrants, except for the Klaas’s Cuckoo which is a resident in some lowland areas. This means that they are absent from the region for most of the year, only moving down from further north in Africa and Asia during the rainy season.
While cuckoos tend to migrate from as early as September, typically most arrive in late October to November. Most of the 15 species we have in South Africa are intra-African migrants, which means that they come down from countries further north within Africa, down to the south of the continent. There are also a few Palearctic migrants, namely the Common (European) Cuckoo and the Lesser Cuckoo, with the Common Cuckoo coming from China, Korea and Japan and the Lesser Cuckoo coming from Afghanistan and the foothills of the Himalayas. These Palearctic migrants are, however, much less common than the intra-African migrants.
One of the reasons cuckoos migrate down to our neck of the woods is to feast upon the vast insect numbers that come to life after the early summer rains have fallen – specifically to eat the processionary worms (hairy caterpillars) that you will often see huddled together on tree branches, particularly on the Velvet Corkwood tree (Commiphora mollis). In fact, cuckoos are specialised in eating the hairy caterpillars, which are – for good reason – avoided by most other birds. For their meals, cuckoos smash the caterpillars against branches and other objects to remove the caterpillar’s irritating hairs. These caterpillars are the larval stage of the reticulate bagnest moth (Anaphe reticulata).
In spite of their dark reputation (see the books mentioned above and the saying “you’ve gone cuckoo”!), cuckoos are renowned for having very musical songs. That said, not all species are known for holding a tune with the Clamator cuckoos (Levaillant’s, Jacobin and great spotted cuckoo’s) have more of a chattering, unmusical call. But a few have such characteristic songs that it has resulted in their actual common name. For example, the red-chested cuckoo is called the Piet-my-vrou in Afrikaans, which is an onomatopoeic rendition of the distinct “quid-pro-quo” sounding call it monotonously sings. The Diederick cuckoo is called a Diederikkie in Afrikaans which is also a reference to its call which sounds like “dee-dee-deederick”.
Most cuckoos that migrate to Southern Africa breed during their stay here. Their breeding behaviour is very interesting and unlike that of most other birds. All of the locally occurring cuckoos are what we call “brood parasites”. A “brood parasite” is a bird that lays its eggs or egg in another bird’s nest, in the hopes that their clutch will outcompete the host’s eggs and the host bird will incubate and raise the cuckoo’s chicks. This is done for a few reasons: the cuckoo expends less energy as it does not need to raise its own chick and by laying eggs in a few different nests, the risk is spread and therefore the chances of the chicks being successfully raised is increased. To achieve this parasitism, cuckoos have developed techniques to trick their host birds: most cuckoos have developed what is called “egg-mimicry” in which their eggs look similar in size, colour and shape to that of the host’s egg. Typically, the cuckoo will also evict an egg from the host nest, for each one she lays. When they hatch, some cuckoos – like the African emerald cuckoo and the Diederick – will even evict unhatched host eggs. After hatching (and while still blind) the hatchling will back up to the host’s egg, collect it in a special cavity and then toss it over the edge of the nest. They may do this to the host’s young chicks as well. Alternatively, the cuckoo chick will hack and peck the host chicks to death once they have hatched – and which might just help explain their reputation in popular culture! However, in some cases, the parasite and host chicks are raised together without any hostility.
Another interesting point to add is that males often perform “courtship-feeding”, in which they feed caterpillars to females in an attempt to court them. This often leads people to believe that the cuckoo is feeding one of its own, yet this is not true as no local cuckoo species raises its young.
Cuckoos are amazing birds and are fascinating even to non-twitchers, particularly for their long-distance travel, nesting behaviour and beautiful melodic calls. Unfortunately, however, catching sight of a cuckoo is not easy as they are only seen – and more often just heard – in the rainy season.
This, however, just makes their presence more special as they are here to tell us that summer has well and truly begun!
Are you keen on birds or learning more about them, have a look at our Birding in the Bush course we offer.
Still want to learn something more today, have a look at the bird quizzes we have available: