02 Nov Brood Parasites
by Gerhardt Lorist
A bird that lays its eggs in the nest(s) of other (foster or host) species, e.g. Honeyguides, Cuckoos, Indigobirds (widowfinch) and Whydahs. (ref: Roberts Birds of Southern Africa)
We all know that Cuckoos do not raise their own young but lay their eggs in the nests of other birds, but not many people know of the other brood parasites like Honeyguides, Indigobirds (widowfinch) and Whydahs.
These birds have a variety of hosts they use and one specific brood parasite might have a few different host species that they parasitize.
The behaviour of the different brood parasites and their offspring also vary, the most common behaviour is that the egg is laid and the chick grows faster than that of the host species and thus take all the food and space in the nest. The host chicks normally die resulting in the host parent only feeding the parasite chick. In some cases, like Levailant’s Cuckoo (Striped cuckoo), the chick is raised gregariously with the chicks of the host parent which in this case is Arrow-marked Babblers.
There are other more aggressive behaviours where the hosts eggs or chicks are removed from the nest by the parasite adult or, in some cases, even by the hatchlings. The most aggressive form of brood parasitism is that of the Honeyguides. The parent will often peck at the chick or eggs in the nest and, when the parasite nestling is hatched, it will also attack and kill the host chicks with bill hooks (the bill hooks normally falls off about 14 days after hatching)
In the case we have at the Main gate, we think that the Crested Barbet nest is parasitized by a Greater Honeyguide. (Although Lesser Honeyguides also parasitize Crested Barbets, they normally prefer Black-collared Barbets.)
Honeyguides only parasitize hole nesting birds like Barbets, Bee-eaters and Kingfishers. Greater Honeyguides prefer Green Woodhoopoe, African Hoopoe, Little bee-eaters and Crested Barbets.
We will only know which species has parasitized the barbet nest once the chick is out of the nest, the host will normally still feed the young around the nest side for about 10 days. I will monitor the nest and photograph the young once it is out of the nest.