The greater honeyguide is about 20 cm long and weighs about 50 g. Like all African honeyguides, it has bold white patches on the sides of the tail. The male has dark grey-brown upperparts and white underparts, with a black throat. The wings are streaked whitish, and there is a yellow shoulder patch. The bill is pink. The female is duller and lacks the black throat. Her bill is blackish. Immature birds are very distinctive, having olive-brown upperparts with a white rump and yellow throat and upper breast.
Diet
Bee colonies
The greater honeyguide feeds primarily on the contents of bee colonies : bee eggs, larvae and pupae; waxworms; and beeswax. It frequently associates with other honeyguides at bees' nests; immatures dominate adults, and immatures of this species dominate all others. Like other honeyguides, the greater honeyguide enters bees' nests while the bees are torpid in the early morning, feeds at abandoned hives, and scavenges at hives robbed by people or other large animals, notably the ratel or honey badger.
Guiding of humans
The greater honeyguide is known to guide people to the nests of wild bees. Guiding is unpredictable and is more common among immatures and females than adult males. A guiding bird attracts a person's attention with wavering, chattering "'tya' notes compounded with peeps or pipes", sounds it also gives in aggression. The guiding bird flies toward an occupied nest and then stops and calls again. As in other situations, it spreads its tail, showing the white spots, and has a "bounding, upward flight to a perch", which make it conspicuous. If the followers are native honey-hunters, when they reach the nest they incapacitate the adult bees with smoke and open the nest with axes or pangas. After they take the honey, the honeyguide eats whatever is left. One study found that use of honeyguides by the Boran people of East Africa reduces their search time for honey by approximately two-thirds. Because of this benefit, the Boran use a specific loud whistle, known as the fuulido, when a search for honey is about to begin. The fuulido doubles the encounter rate with honeyguides. Another study of the Yao honey-hunters in northern Mozambique showed that the honeyguides responded to the traditional brrrr-hmm call of the honey-hunters. The chances of finding a bee-hive were greatly increased when the traditional call was used. The tradition of the Bushmen and most other tribes says that the honeyguide must be thanked with a gift of honey; if not, it may lead its follower to a lion, bull elephant, or venomous snake as punishment. However, “others maintain that honeycomb spoils the bird, and leave it to find its own bits of comb”. Some Greater Honeyguides stopped this guiding behavior, or mutualism, in parts of Kenya, due to a loss of response from people in the area.
Possible guiding of non-human animals
Many sources say that this species also guides honey badgers. Friedmann notes that Sparrman said in the 18th century that indigenous Africans reported this interaction, but Friedmann adds that no biologist has seen it. According to Dean and MacDonald, Friedmann does quote reports that greater honeyguides guide baboons and speculates that the behavior evolved in relation to these species before the appearance of humanity. However, they state,
In addition to that listed by Friedmann, the only recent record is of a greater honeyguide giving its guiding call to baboons at Wankie Game Reserve, Zimbabwe. However, Vernon did not see a positive response by the baboons to the honeyguide. No additional records of honeyguides and ratels have been reported since Friedmann and the first-hand accounts given in his review in support of this association are all of incomplete guiding sequences. No biologist has ever reported this association.
Dean and MacDonald go on to express doubt that honeyguides guide other animals and suggest that the behavior may have evolved with "early man". It has also been acknowledged that bee colonies are seasonally very common in Africa and ratels probably have no trouble finding them. Another argument against guiding of non-human animals is that near cities, where Africans increasingly buy sugar rather than hunting for wild honey, guiding behavior is disappearing. Ultimately it may disappear everywhere.
Other food
The greater honeyguide also catches some flying insects, especially swarming termites. It sometimes follows mammals or birds to catch the insects they flush, and joins mixed-species flocks in ones and twos. It has been known to eat the eggs of small birds.
Reproduction
In addition to being a predator of insects and a mutualist with its follower species, the greater honeyguide is a brood parasite. It lays white eggs in series of 3 to 7, for a total of 10 to 20 in a year. Each egg is laid in a different nest of a bird of another species, including some woodpeckers, barbets, kingfishers, bee-eaters, wood hoopoes, starlings, and large swallows. It is common for the female Greater Honeyguide to break the host's eggs when laying her own. All the species parasitized nest in holes, covered nests, or deep cup nests. The chick has a membranous hook on the bill that it uses, while still blind and featherless, to kill the host's young outright or by repeated wounds.
