man power

Observations of Black Coucal breeding in Mtunzini, KwaZulu-Natal

- HUGH CHITTENDEN

The extraordinary breeding behaviour of the Black Coucal Centropus grillii has piqued the interest of ornithologists for decades, so much so that the species is now regarded as one of the most unusual birds in the world. Of the 28 coucal species found globally, it is the only one known to be polyandrous. The southern African population, moreover, is the only one that is migratory.

Polyandry is rare among the world’s birds and has been recorded in only about one per cent of species. In this role-reversal mating system, after laying the eggs the female plays no further part in raising the young. What makes the Black Coucal even more remarkable is the fact that its offspring are altricial (hatched in an undeveloped state and requiring care and feeding by the parents), which is almost unknown in polyandrous species. In general they rear precocial chicks, which are far easier to manage as, almost from day one, they are able to accompany the males to feeding sites where they are fed and protected by the male. In the subregion, the species best known to practise this mating system is the African Jacana, but there are others, such as the Greater Painted-snipe and the three buttonquail species.

Among polyandrous species, however, the Black Coucal differs in that the males not only are responsible for nest building, incubation and rearing the offspring, but they also have the task of provisioning and protecting altricial chicks for the two-week nestling period. Once the chicks are three or four days old, the male leaves them alone and unattended in the nest for at least 95 per cent of the day while he searches for food as far as half a kilometre away. During this time, he maintains an exceptionally high rate of prey delivery, which can only be achieved at a site where there is an abundant supply of invertebrate prey.