The Greater Honeyguide (Indicator indicator) is fairly common and widespread, occurring widely in the Sahel and sub-Saharan Africa, except in desert, forest, and grassland; it is found in all but the desert parts of western South Africa. The distribution extends from Senegal and southern Mali south almost to the coast, east to Eritrea and south (around the main forested belt) through east-central Africa (including eastern and southern DRC and much of East Africa), and from Angola, northeastern Namibia, and northern and eastern Botswana to Mozambique and south to the former Cape Province (South Africa).
Greater Honeyguides are found in open woods, woodland edges, bushland, streamside woods, bushes in dry areas, plantations, gardens with trees, thickets, and trees lining suburban streets; they are often seen in the vicinity of bees' nests. They may be found up to 2000 m (occasionally to 3000 m in East Africa).
These birds have an unusual diet, feeding extensively on beeswax (which they digest readily), as well as on honeybee larvae and eggs and a range of other insects (including termites, winged ants, flies, and others). The nestlings, which are raised in the nests of other species (see below), feed on food provided by their host, including fruits. Immatures generally dominate around bees' nests. In some areas, Greater Honeyguides (often immature birds) lead humans to bees' nests. After the human honey gatherers have opened and left the nest, the bird feeds on pieces of honeycomb left behind. From these, it extracts mainly the larvae and the wax to supplement its diet of insects. (For more details on the symbiotic relationship between traditional human honey gatherers and honeyguides, see Isack and Reyer 1989.)
Greater Honeyguides are brood parasites, laying their eggs in the nests of a diverse set of avian host species (mainly from the Coraciiformes and Upupiformes) at any given location. They typically deposit just a single egg per nest (sometimes more), laying up to 20 total. Females typically puncture the host's eggs when laying their own, but in many nests at least one host egg survives. The young honeyguides finish the job. Spottiswoode and Koorevaar (2012) found that hosts always hatched after honeyguide chicks (presumably in part due to an additional period of internal incubation in female honeyguides; Birkhead et al. 2011) and were killed within hours by honeyguide nestlings, which utilize a specialized sharp hook on their bills (this hook is lost after 2 weeks or more). Despite being blind and in total darkness, honeyguide chicks attack host young with sustained biting, grasping, and shaking motions, as seen in these videos. Attacks of just a few minutes in duration are sufficient to cause death, although it may sometimes be delayed for hours. Young Greater Honeyguides fledge at 35 to 40 days and are usually independent in just a few days. Greater Honeyguides are mainly resident, but may disperse 20 km or more and regularly move 8 to 10 km (juveniles disperse to 8 to 10 km in a few days). Greater Honeyguides may live to 12 years or even longer.
Spottiswoode et al. (2011) showed that Greater Honeyguides exhibit host-specific differentiation in both egg size and egg shape (mimicry of egg color is presumably of less importance in birds nesting in dark tree cavities). Genetic analysis of honeyguide eggs and chicks revealed that two highly divergent mitochondrial DNA (mtDNA) lineages are associated with ground- and tree-nesting hosts, respectively, indicating strong fidelity to two mutually exclusive sets of host species for millions of years. However, despite their age and apparent adaptive diversification, these ancient lineages do not represent cryptic species: a complete lack of differentiation in nuclear genes (which are biparentally inherited rather than maternally inherited, as is mtDNA) indicates that male and female honeyguides reared by different hosts must interbreed sufficiently often to prevent divergence at neutral nuclear loci. Thus, ancient host-specific female lineages apparently have apparently been maintained in the absence of any detectable reproductive isolation.
Female specificity in host use is remarkably strong and maternally inherited, whether genetically (e.g. on the female-specific W chromosome) or culturally (e.g., via behavioral imprinting on young female honeyguides). Matters are complicated by the presence of phenotypic differentiation within the lineage specializing on treehole-nesting hosts.
The male Greater Honeyguide is unmistakable: brown above with black throat, white cheeks, pink bill, a yellow/golden shoulder patch, white outer tail patches, and short outer tail feathers.
- Birkhead, T.R., N. Hemmings, C.N. Spottiswoode, O. Mikulica, C. Moskát, M. Bán, and K. Schulze-Hagen. 2011. Internal incubation and early hatching in brood parasitic birds. Proceedings of the Royal Society B 278(1708): 1019-1024.
- Diamond, A.W. and A.R. Place. 1988. Wax digestion by Black-throated Honeyguides Indicator indicator. Ibis 130(4): 558-561.
- Isack, H.A. and H.U. Reyer. 1989. Honeyguides and honey gatherers--interspecific communication in a symbiotic relationship. Science 243(4896): 1343-1346.
- Short. L.L. and J.F.M. Horne 2002. Greater Honeyguide Indicator indicator. P. 294 in: del Hoyo, J., Elliott, A., and Sargatal, J., eds. Handbook of the Birds of the World. Volume 7. Jacamars to Woodpeckers. Lynx Edicions, Barcelona.
- Spottiswoode, C.N. and J. Koorevaar. 2012. A stab in the dark: chick killing by brood parasitic honeyguides. Biology Letters 8(2): 241-244.
- Spottiswoode, C.N., K.F. Stryjewski, S. Quader, J.F.R. Colebrook-Robjent, and M.D. Sorenson. 2011. Ancient host specificity within a single species of brood parasitic bird. Proceedings of the National Academy of Sciences (U.S.A.) 108(43): 17738-17742.
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