The oxpeckers are two
species
In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...
of bird which make up the
genus
Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...
''Buphagus'', and
family
Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...
Buphagidae. The oxpeckers were formerly usually treated as a
subfamily
In biological classification, a subfamily (Latin: ', plural ') is an auxiliary (intermediate) taxonomic rank, next below family but more inclusive than genus. Standard nomenclature rules end subfamily botanical names with "-oideae", and zoologi ...
, Buphaginae, within the starling family,
Sturnidae, but
molecular phylogenetic
Molecular phylogenetics () is the branch of phylogeny that analyzes genetic, hereditary molecular differences, predominantly in DNA sequences, to gain information on an organism's evolutionary relationships. From these analyses, it is possible to ...
studies have consistently shown that they form a separate lineage that is
basal to the
sister clades
In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree.
Definition
The expression is most easily illustrated by a cladogram:
Taxon A and t ...
containing the Sturnidae and the
Mimidae (mockingbirds, thrashers, and allies). Oxpeckers are endemic to the
savanna
A savanna or savannah is a mixed woodland-grassland (i.e. grassy woodland) ecosystem characterised by the trees being sufficiently widely spaced so that the canopy does not close. The open canopy allows sufficient light to reach the ground to ...
of
Sub-Saharan Africa
Sub-Saharan Africa is, geographically, the area and regions of the continent of Africa that lies south of the Sahara. These include West Africa, East Africa, Central Africa, and Southern Africa. Geopolitically, in addition to the List of sov ...
.
Both the
English
English usually refers to:
* English language
* English people
English may also refer to:
Peoples, culture, and language
* ''English'', an adjective for something of, from, or related to England
** English national ide ...
and scientific names arise from their habit of perching on large
mammal
Mammals () are a group of vertebrate animals constituting the class Mammalia (), characterized by the presence of mammary glands which in females produce milk for feeding (nursing) their young, a neocortex (a region of the brain), fur or ...
s (both wild and domesticated) such as
cattle
Cattle (''Bos taurus'') are large, domesticated, cloven-hooved, herbivores. They are a prominent modern member of the subfamily Bovinae and the most widespread species of the genus ''Bos''. Adult females are referred to as cows and adult mal ...
,
zebra
Zebras (, ) (subgenus ''Hippotigris'') are African equines with distinctive black-and-white striped coats. There are three living species: the Grévy's zebra (''Equus grevyi''), plains zebra (''E. quagga''), and the mountain zebra (''E. zeb ...
s,
impala
The impala or rooibok (''Aepyceros melampus'') is a medium-sized antelope found in eastern and southern Africa. The only extant member of the genus '' Aepyceros'' and tribe Aepycerotini, it was first described to European audiences by Germa ...
s,
hippopotamus
The hippopotamus ( ; : hippopotamuses or hippopotami; ''Hippopotamus amphibius''), also called the hippo, common hippopotamus, or river hippopotamus, is a large semiaquatic mammal native to sub-Saharan Africa. It is one of only two extan ...
es,
rhinoceros
A rhinoceros (; ; ), commonly abbreviated to rhino, is a member of any of the five extant species (or numerous extinct species) of odd-toed ungulates in the family Rhinocerotidae. (It can also refer to a member of any of the extinct species o ...
es, and
giraffe
The giraffe is a large African hoofed mammal belonging to the genus ''Giraffa''. It is the tallest living terrestrial animal and the largest ruminant on Earth. Traditionally, giraffes were thought to be one species, ''Giraffa camelopardalis ...
s, eating
tick
Ticks (order Ixodida) are parasitic arachnids that are part of the mite superorder Parasitiformes. Adult ticks are approximately 3 to 5 mm in length depending on age, sex, species, and "fullness". Ticks are external parasites, living by ...
s, small insects,
botfly
Botflies, also known as warble flies, heel flies, and gadflies, are a family of flies known as the Oestridae. Their larvae are internal parasites of mammals, some species growing in the host's flesh and others within the gut. ''Dermatobia homin ...
larvae, and other parasites, as well as the animals' blood. The behaviour of oxpeckers towards large
mammal
Mammals () are a group of vertebrate animals constituting the class Mammalia (), characterized by the presence of mammary glands which in females produce milk for feeding (nursing) their young, a neocortex (a region of the brain), fur or ...
s was thought to be exclusively
mutual, though recent research suggests the relationship can be
parasitic
Parasitism is a close relationship between species, where one organism, the parasite, lives on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The entomologist E. O. Wilson has c ...
in nature as well.
The
swahili name for the red-billed oxpecker is
Askari
An askari (from Somali, Swahili and Arabic , , meaning "soldier" or "military", which also means "police" in the Somali language) was a local soldier serving in the armies of the European colonial powers in Africa, particularly in the African G ...
wa kifaru (the rhino's guard).
Taxonomy
The genus ''Buphagus'' was introduced in 1760 by the French zoologist
Mathurin Jacques Brisson
Mathurin Jacques Brisson (; 30 April 1723 – 23 June 1806) was a French zoologist and natural philosopher.
Brisson was born at Fontenay-le-Comte. The earlier part of his life was spent in the pursuit of natural history; his published works ...
with the
yellow-billed oxpecker
The yellow-billed oxpecker (''Buphagus africanus'') is a passerine bird in the family Buphagidae. It was previously placed in the starling and myna family, Sturnidae.
It is native to the savannah of Sub-Saharan Africa from Senegal east to Sudan. ...
as the
type species
In zoological nomenclature, a type species (''species typica'') is the species name with which the name of a genus or subgenus is considered to be permanently taxonomically associated, i.e., the species that contains the biological type specimen ...
. The name combines the
Ancient Greek
Ancient Greek includes the forms of the Greek language used in ancient Greece and the ancient world from around 1500 BC to 300 BC. It is often roughly divided into the following periods: Mycenaean Greek (), Dark Ages (), the Archaic peri ...
words ''bous'' "ox" and ''-'' "eating".
According to the more recent studies of
Muscicapoidea phylogeny
A phylogenetic tree (also phylogeny or evolutionary tree Felsenstein J. (2004). ''Inferring Phylogenies'' Sinauer Associates: Sunderland, MA.) is a branching diagram or a tree showing the evolutionary relationships among various biological spec ...
, the oxpeckers are an ancient line related to
Mimidae (mockingbirds and thrashers) and starlings but not particularly close to either.
Considering the known
biogeography
Biogeography is the study of the distribution of species and ecosystems in geographic space and through geological time. Organisms and biological communities often vary in a regular fashion along geographic gradients of latitude, elevation, ...
of these groups, the most plausible explanation seems that the oxpecker lineage originated in Eastern or Southeastern Asia like the other two.
This would make the two species of ''Buphagus'' something like
living fossil
A living fossil is an extant taxon that cosmetically resembles related species known only from the fossil record. To be considered a living fossil, the fossil species must be old relative to the time of origin of the extant clade. Living fossi ...
s, and demonstrates that such remnants of past
evolution
Evolution is change in the heritable characteristics of biological populations over successive generations. These characteristics are the expressions of genes, which are passed on from parent to offspring during reproduction. Variation ...
can possess striking and unique
autapomorph
In phylogenetics, an autapomorphy is a distinctive feature, known as a derived trait, that is unique to a given taxon. That is, it is found only in one taxon, but not found in any others or outgroup taxa, not even those most closely related to t ...
ic adaptations.
The genus contains two species:
Distribution and habitat
The oxpeckers are
endemic
Endemism is the state of a species being found in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also found elsew ...
to sub-Saharan Africa, where they occur in most open
habitat
In ecology, the term habitat summarises the array of resources, physical and biotic factors that are present in an area, such as to support the survival and reproduction of a particular species. A species habitat can be seen as the physical ...
s. They are absent from the driest
desert
A desert is a barren area of landscape where little precipitation occurs and, consequently, living conditions are hostile for plant and animal life. The lack of vegetation exposes the unprotected surface of the ground to denudation. About on ...
s and the
rainforest
Rainforests are characterized by a closed and continuous tree canopy, moisture-dependent vegetation, the presence of epiphytes and lianas and the absence of wildfire. Rainforest can be classified as tropical rainforest or temperate rainfores ...
s. Their distribution is restricted by the presence of their preferred
prey
Predation is a biological interaction where one organism, the predator, kills and eats another organism, its prey. It is one of a family of common feeding behaviours that includes parasitism and micropredation (which usually do not kill the ...
, specific species of
tick
Ticks (order Ixodida) are parasitic arachnids that are part of the mite superorder Parasitiformes. Adult ticks are approximately 3 to 5 mm in length depending on age, sex, species, and "fullness". Ticks are external parasites, living by ...
s, and the animal hosts of those ticks. The two species of oxpecker are
sympatric
In biology, two related species or populations are considered sympatric when they exist in the same geographic area and thus frequently encounter one another. An initially interbreeding population that splits into two or more distinct species sh ...
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.
Behaviour
Diet and feeding
Oxpeckers graze exclusively on the bodies of large mammals. Certain species are seemingly preferred, whereas others, like the
Lichtenstein's hartebeest
Lichtenstein's hartebeest (''Alcelaphus buselaphus lichtensteinii'')Wilson, Don E. & Reeder, DeeAnn M. (editors). 2005. Mammal Species of the World. A Taxonomic and Geographic Reference (3rd ed), Johns Hopkins University Press, 2,142 ppAvailable ...
or
topi
''Damaliscus lunatus jimela'' is a subspecies of topi, and is usually just called a topi. It is a highly social and fast type of antelope found in the savannas, semi-deserts, and floodplains of sub-Saharan Africa.
Names
The word ''tope'' o ...
are generally avoided. Smaller antelope such as
lechwe
The lechwe, red lechwe, or southern lechwe (''Kobus leche'') is an antelope found in wetlands of south-central Africa.
Range
The lechwe is native to Botswana, Zambia, southeastern Democratic Republic of the Congo, northeastern Namibia, and eas ...
,
duiker
A duiker is a small to medium-sized brown antelope native to sub-Saharan Africa, found in heavily wooded areas. The 22 extant species, including three sometimes considered to be subspecies of the other species, form the subfamily Cephalophina ...
s and
reedbuck
Reedbuck is a common name for Africa
Africa is the world's second-largest and second-most populous continent, after Asia in both cases. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it ...
are also avoided; the smallest regularly used species is the
impala
The impala or rooibok (''Aepyceros melampus'') is a medium-sized antelope found in eastern and southern Africa. The only extant member of the genus '' Aepyceros'' and tribe Aepycerotini, it was first described to European audiences by Germa ...
, 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 on
ectoparasites
Parasitism is a close relationship between species, where one organism, the parasite, lives on or inside another organism, the host, causing it some harm, and is adapted structurally to this way of life. The entomologist E. O. Wilson has ...
, 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.
Oxpecker/mammal interactions are the subject of some debate and ongoing research.
They were originally thought to be an example of
mutualism, but recent evidence suggests that oxpeckers may be parasites instead.
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.
[ Oxpeckers have been observed to open new wounds and enhance existing ones in order to drink the blood of their perches.] 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. [ Some oxpeckers' hosts are intolerant of their presence.] 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. Other species tolerate oxpeckers while they search for ticks on their faces, which one author says "appears ... to be an uncomfortable and invasive process.
Breeding
The breeding 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 and copulation 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 typical clutch
A clutch is a mechanical device that engages and disengages power transmission, especially from a drive shaft to a driven shaft. In the simplest application, clutches connect and disconnect two rotating shafts (drive shafts or line shafts). ...
is between two and three eggs
Humans and human ancestors have scavenged and eaten animal eggs for millions of years. Humans in Southeast Asia had domesticated chickens and harvested their eggs for food by 1,500 BCE. The most widely consumed eggs are those of fowl, especial ...
, but the red-billed oxpecker
The red-billed oxpecker (''Buphagus erythrorynchus'') is a passerine bird in the oxpecker family, Buphagidae. It is native to the savannah of sub- Saharan Africa, from the Central African Republic east to South Sudan and south to northern and eas ...
may lay up to five eggs.
Roosting
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.
References
{{Taxonbar, from1=Q644442, from2=Q13971067
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*
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Hematophages
Parasitic vertebrates