|Ecology 6e Chapter 15 Online Supplementary Materials
Honeyguide Natural History
Honeyguides belong to the family Indicatoridae in the order Piciformes, an order that also includes the woodpeckers. The family Indicatoridae includes a total of 17 species, 15 of which are native to Africa. Honeyguides have the unusual habit of feeding on waxes of various sorts—most feed on beeswax and insects. Of the 17 species of honeyguides, only the greater honeyguide, I. indicator, is known to guide humans and a few other mammals to bees’ nests.
The greater honeyguide is found throughout much of sub-Saharan Africa. It avoids only dense forests and very open grasslands and desert, and its distribution corresponds broadly with the distributions of tropical savanna and tropical dry forest. Like all of the honeyguides, the greater honeyguide is a brood parasite that, like cuckoos, lays its eggs in the nests of other birds. This way of life is reflected in the early morphology of nestling honeyguides, which retain “bill hooks” on their upper and lower bills for the first 14 days of life that they use to lacerate and kill their nest mates. However, nests sometimes contain two honeyguide nestlings, so apparently there is some mechanism by which nestlings of the same species can coexist. After the deaths of their nest mates, honeyguide nestlings receive all the food brought by their foster parents, which continue to feed young honeyguides until they are completely independent, approximately 7 to 10 days after leaving the nest.
Greater honeyguides are capable of completely independent life without mutualistic interactions with humans, so we would classify their mutualistic relationship with humans as facultative. Living independently, honeyguides feed on beeswax, and on the adults, larvae, pupae, and eggs of bees. They also feed on a wide variety of other insects. Greater honeyguides show highly opportunistic feeding behavior and sometimes join flocks of other bird species foraging on the insects stirred up by large mammals. The most distinguishing feature of the greater honeyguide, however, is its habit of guiding humans and ratels, or honey badgers, to bees’ nests.
The first written report of the guiding behavior of I. indicator was authored in 1569 by João Dos Santos, a missionary in the part of East Africa that is now Mozambique. Dos Santos first noticed honeyguides because they would enter the mission church to feed upon the bits of beeswax on candlesticks. He went on to describe their guiding behavior by saying that when the birds find a beehive, they search for people and attempt to lead them to the hive. He noted that the local people eagerly followed the birds because of their fondness for honey, and he observed that the honeyguide profits by gaining access to the wax and dead bees left after humans raid the hive. Dos Santos’s report of this behavior was confirmed by other European visitors to almost all parts of Africa for the next four centuries. However, it wasn’t until the middle of the twentieth century that the mutualism of honeyguides with humans was examined scientifically. The foundation work of these studies was that of H. Friedmann (1955), who reviewed and organized the observations of others, including those of Dos Santos, and who conducted his own extensive research on the honeyguides of Africa.
Friedmann’s report of some of the African legends surrounding the greater honeyguide suggests that a wide variety of African cultures prescribed rewarding the bird for its guiding behavior and that native Africans recognized the need for reciprocity in their interactions with honeyguides. One proverb reported by Friedmann was, “If you do not leave anything for the guide [I. Indicator], it will not lead you at all in the future.” Another proverb stated more ominously, “If you do not leave anything for the guide, it will lead you to a dangerous animal the next time.” Friedmann also observed that many African cultures forbid killing a honeyguide and once “inflicted severe penalties” for doing so. These observations suggest long association between humans and honeyguides and that the association has been consciously mutualistic on the human side of the balance sheet.