| Oxpeckers | |
|---|---|
_on_zebra.jpg) | |
| Yellow-billed oxpeckers Buphagus africanus africanus on a zebra in Senegal | |
Scientific classification | |
| Domain: | Eukaryota |
| Kingdom: | Animalia |
| Phylum: | Chordata |
| Class: | Aves |
| Order: | Passeriformes |
| Superfamily: | Muscicapoidea |
| Family: | Buphagidae Lesson, 1828 |
| Genus: | Buphagus Brisson, 1760 |
| Type species | |
| Buphaga africana[1] Linnaeus, 1766 | |
| Species | |
_on_impala_(Aepyceros_melampus).jpg)
Theoxpeckers are twospecies of bird which make up thegenusBuphagus, fromAncient Greek βοῦς (boûs), meaning "ox", and φάγος (phágos), meaning "eater", andfamilyBuphagidae. The oxpeckers were formerly usually treated as asubfamily, Buphaginae, within the starling family,Sturnidae, butmolecular phylogenetic studies have consistently shown that they form a separate lineage that isbasal to thesister clades containing the Sturnidae and theMimidae (mockingbirds, thrashers, and allies). Oxpeckers are endemic to thesavanna ofSub-Saharan Africa.
Both theEnglish and scientific names arise from their habit of perching on largemammals (both wild and domesticated) such ascattle,zebras,impalas,hippopotamuses,rhinoceroses, andgiraffes, eatingticks, small insects,botfly larvae, and other parasites, as well as the animals' blood. The behaviour of oxpeckers towards largemammals was thought to be exclusivelymutual, though recent research suggests the relationship can beparasitic in nature as well.[2]
TheSwahili name for the red-billed oxpecker isAskari wa kifaru (the rhino's guard).[3]
The genusBuphagus was introduced in 1760 by the French zoologistMathurin Jacques Brisson with theyellow-billed oxpecker as thetype species.[4] The name comes fromAncient Greek βοῦς (boûs), meaning "ox", and φάγος (phágos), meaning "eater".[5]
According to the more recent studies ofMuscicapoideaphylogeny, the oxpeckers are an ancient line related toMimidae (mockingbirds and thrashers) and starlings but not particularly close to either.[6][7][8] Considering the knownbiogeography of these groups, the most plausible explanation seems that the oxpecker lineage originated in Eastern or Southeastern Asia like the other two.[7] This would make the two species ofBuphagus something likeliving fossils, and demonstrates that such remnants of pastevolution can possess striking and uniqueautapomorphic adaptations.
The genus contains two species:[9]
| Common name | Scientific name and subspecies | Range | Size and ecology | IUCN status and estimated population |
|---|---|---|---|---|
| Yellow-billed oxpecker
| Buphagus africanus Linnaeus, 1766 Two subspecies
| most of sub-Saharan Africa | Size: Habitat: Diet: | LC |
| Red-billed oxpecker
| Buphagus erythrorynchus (Stanley, 1814) | mainly east Africa | Size: Habitat: Diet: | LC |
The oxpeckers areendemic to sub-Saharan Africa, where they occur in most openhabitats. They are absent from the driestdeserts and therainforests. Their distribution is restricted by the presence of their preferredprey, specific species ofticks, and the animal hosts of those ticks. The two species of oxpecker aresympatric over much of East Africa and may even occur on the same host animal. The nature of the interactions between the two species is unknown.
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Oxpeckers graze exclusively on the bodies of large mammals. Certain species are seemingly preferred, whereas others, like theLichtenstein's hartebeest ortopi are generally avoided. Smaller antelope such aslechwe,duikers andreedbuck are also avoided; the smallest regularly used species is theimpala, probably because of the heavy tick load and social nature of that species. In many parts of their range they now feed on cattle, but avoid camels. They feed onectoparasites, particularly ticks, as well as insects infesting wounds and the flesh and blood of some wounds as well. They are sometimes classified as parasites, because they open wounds on the animals' backs.[10]
Oxpecker/mammal interactions are the subject of some debate and ongoing research.[11] They were originally thought to be an example ofmutualism, but recent evidence suggests that oxpeckers may be parasites instead.[12] Oxpeckers do eat ticks, but often the ticks have already fed on the ungulate host, and no statistically significant link has been shown between oxpecker presence and reduced ectoparasite load.[12] Oxpeckers have been observed to open new wounds and enhance existing ones in order to drink the blood of their perches.[13] Oxpeckers also feed on the earwax and dandruff of mammals; less is known about the possible benefits of this to the mammal, but it is suspected that this is also a parasitic behaviour.[12] Some oxpeckers' hosts are intolerant of their presence.[13] Elephants and some antelope will actively dislodge the oxpeckers when they land. However there have been noted instances of elephants allowing oxpeckers to eat parasites off of them.[14] Other species tolerate oxpeckers while they search for ticks on their faces, which one author says "appears ... to be an uncomfortable and invasive process."[10]
Thebreeding season of the oxpeckers, in at least one location, is linked to the rainy season, which affects the activity of their mammalian hosts and the tick loads of those hosts. Both courtship andcopulation occur on their hosts as well. They nest in holes, usually in trees but sometimes in other types of cavity, including holes in walls. The nests are lined with grasses and often with hair plucked from their hosts and even livestock such as sheep which are not usually used. The typicalclutch is between two and threeeggs, but thered-billed oxpecker may lay up to five eggs.
Red-billed oxpeckers have been known to roost in reeds and trees. Studies of large savanna herbivores using cameras at night have shown that both species of oxpecker (but more often in yellow-billed oxpecker) may also roost on the bodies of herbivores, hanging under the insides of the thighs of giraffe and on top of impala and buffalo.[15]
_adult_(L)_sub-adult_(R)_on_impala.jpg)