Table Of ContentOxpeckers, the genus Buphagus
Randall Breitwisch
Resume: Les deux especes de pique-boeufs -le Pique-boeufa bee jaune Bughagusafricanus et le
,
Pique-boeufa bee rouge B. erythrorhynchus- occupent la savane et les habitats de bois ouverts en
Afriquesub-saharienneetchevauchentl’Afriqueaustraleetl’Afriquede l’Est. En raisonde la presence
decaracteristiquescommunes du squeletteetlamusculature, ilssont classescommedes membresde
lafamilledel’etourneau,lesSturnidees,dont111especes setrouventprincipalementenAfriqueetdans
lesuddel’Asie.Toutefois, alorsqu’ungrandnombredetourneauxafricainsontunplumagechatoyant
et des couleurs vives, ce n’est pasle cas des pique-boeufs.
The two species ofoxpeckers (or tickbirds) - the
Yellow-billedBuphagusafricanusandRed-billed
B. erythrorhynchus- occupy savanna and open
woodlandhabitatsinsub-SaharanAfrica,over-
lapping in southern and eastern Africa.
Owingtothepresenceofsharedcharac-
teristics ofskeleton and musculature
theyare classified as members of
the starling family, Sturnidae,
the111speciesofwhichare
found primarily in Africa
and southern Asia. How-
ever,whilemanyAfrican
starlings have richly
coloured, iridescent
plumages, oxpeckers
donot.Onthebasisof
morphological, ana-
tomical,andbehavioural
distinctiveness,
oxpeckershavepreviously
been accorded subfamily
Buphaginae or even family
Buphagidae status, a classifi-
cation nowout offavour.
Themorphologyandbehav-
iourofbothspecieshavebecome
adaptedtoexploitthe arthropods
that live on the skin of large her-
bivorousmammals-onwhichboth
species depend. Oxpeckers are cooperative breed- providesupportwhen thebirdclingstothesideofa
ers, nestingintreecavitiesandlivinginfamilygroups mammal.Theyalsohaverobust,stronglycurved,and
ofup tosixindividuals. sharpclawswhichallowthemtohanginallmannerof
postures while climbing over mammal bodies, even
Evolution
upside down on the legs oronthe belly region. The
Oxpeckersarehighlymodifiedfortheirforagingniche. bill is large and wide at the base, laterally flattened
Morphological adaptations for feeding on mammal along its length, and used in the typical mannerofa
bodiesincludeshortlegstoholdthebodyclosetothe starling, with jabbing motions followed by opening
surface of the mammal and stiff tail feathers that themandiblesandmovingthroughhairorworkinga
Oxpeckers, thegenus Buphagus: Breitwisch BullABC Vo!3 No i -31
wound site for parasitic insects or necrotic tissue.
Oxpeckersalsousetheirbills inascissoringmanner,
held sideways on mammal skin and moved through
the hair. The bones of the palate are modified in
association with this foraging niche. Behaviourally,
oxpeckershaveevolvedanintimaterelationshipwith
large herbivores, and except when actively engaged
innestingduties,theyspendnearlyalldaylighthours
in the company of these mammals. Yellow-billed
Oxpeckers even sometimes roost at night on mam-
mals.
TheYellow-billedOxpeckerhasthebroadergeo-
graphic range, occurring from Ethiopia across the
continent to Senegal andsouth to northern Namibia,
Botswana, and South Africa (but absent from the
forested regions of West and Central Africa). Red-
billed Oxpeckers occur in East Africa from Ethiopia
andwestern Somalia south to northern South Africa.
Breeding
Oxpeckers nest in tree cavities using grasses, other Yellow-billedOxpeckerBuphagusafricanus
herbaceous vegetation, andmammal hair, as nesting MarkAndrews
material and there are also records ofmammal dung
beingused. Hairiscutfromamammal’sbodywiththe TheYellow-billedOxpeckerhasthebasal halfto
same scissoring action ofthe sharp-edged bill that is two-thirdsofthebillbrightyellow,withtheremaining
usedinforagingforinsects.Theclutchsizeisusually apical portionscarlet red. The iris is orange-red, and
2or3eggs(about23x18 nun), with a rangeof1 to 5. there is no eye-ring. Drab, dark brown dorsal and
The eggs are white to bluish-white and either im- breastplumagecontrastswithvariablylighttanplum-
maculate orspotted or blotched with brown to lilac. age in the ventral region. The rump is light tan in
Theyareincubatedforapproximately 12days,witha contrasttothesurroundingdarkbrowndorsal plum-
nestlingperiodofanother28-30days. Fledglingcare
age.
lasts in excess of two months. Fledglings ride on The Red-billed Oxpecker has a fully scarlet red
mammalsandbegforfoodfromanadultforagingon bill. The red-orange iris is surrounded by a bright
thesamemammal.Multi-brooded,oxpeckersattempt
yellow eye-ring of soft skin or wattle. Drab, dark
uptothreenestsduringthelongbreedingperiodthat browndorsalplumageblendsintolighterbrownven-
coincideswiththe rainyseason. tralplumage,notnearlyascontrastingastheverylight
Bothspeciesarecooperativebreeders,withupto ventral plumage of the other species. There is no
three or four individuals (presumably, previous off- discernible rump patch, while the bill isnotas heavy
spring)actingasreproductivehelpersandsharingthe as that ofthe Yellow-billed Oxpecker.
taskoffeedingnestlingsandfledglings. Onlyasingle
Immatures of both species lack the bright bill
pairofbirds in the familygroup breeds.
colour, beingallduskyin immatureYellow-billed. In
Identification theRed-billedOxpeckeritisdullredbasallyanddull
Unmistakable in appearance and behaviour, yellow to green apically. The iris of both species is
oxpeckers are nearly always encountered perching browntodullred-orange,andthereisnoeyewattlein
on and gleaning insects from the bodies of large the immature Red-billed Oxpecker.
herbivorous mammals. They are medium-sized
Species biology
passerines,(18-20cm long), theRed-billedweighing
The most striking aspect of the species’ biology is
about 50gand Yellow-billed about60g. Belowthey obviouslytheassociationwithlargeherbivorousmam-
are lightbrowntotan anddark, drabbrowndorsally. mals. Favoured mammals include rhinoceros
Sexesarealike.Inareasofsympatry,bothspeciescan
Rhinocerotidae, buffalo Syncerus caffer giraffe
be found not only on the same species ofmammals ,
Giraffa Camelopardalis warthogs Phacocherus
but alsoon the same individual mammal. ,
aethiopius,andshort-hairedspeciesofantelope,such
32 BullABC Vol3 No 1 Oxpeckers, thegenus Buphagus: Breitwiscb
as impala Aepycerusmelampusand some species of available body regions. There has been speculation
gazelle.Cattlearealsofavoured. Denselyhairedgraz- that oxpeckers may keep wounds open in foraging,
ing mammals, such as waterbuck Kobus perhapsfarminginsectsbutoxpeckerswouldseemto
ellipsiprymnus,arelessfavoured,asaresmall-bodied do more good than harm in ridding mammals of
species of gazelle Antilopini. African elephants ectoparasites.
Loxondonta africana appear to be intolerant of Oxpeckerssocialisewhileperchingonmammals
oxpeckers. Red-billed are more common in East Af- and even court and copulate on the backs ofmam-
rica where the two species overlap. It has been mals. Whenapproachedbyhumans, thebirdsscurry
suggestedthat,insympatry,theYellow-billedismore over the back to the opposite side of the mammal,
commononnakedorthin-hairedmammals,withthe peer over the back, and give hissing vocalisations.
Red-billed more common on thickly-haired species. Chatteringcalls similarto those ofotherstarlingsare
Despite the theoretical interest in determining how oftengivenwhenthe birds are alarmedorin flight.
two such similar species apportion resources, there Thedegreetowhichoxpeckersmayhaveasym-
are few carefully collected data on the question of biotic defensive warning relationship with large
competition and ecological niche separation. mammals has beenthe subject ofmuch speculation.
Ticksandblood-suckingfliesandtheirlarvaeare Anecdotesaboundonthemammalianalertresponse
thepreferredfoodscapturedfrombothmammalskin to the hissing vocalisations given by the birds in the
and the flesh exposed in injuries. Studies have indi- presenceofhumans(and, perhaps, otherpredators).
cated that several thousand nymphal ticks are eaten In the Kiswahili language, oxpeckers are known as
eachday. Bloodatwoundsitesisalsotaken. Mostof askariwa kifaru, the ‘guardofthe rhinoceros.’ How-
the mammals attended are largely indifferent to ever, the fascinating possibility of there being true
oxpeckeractivities,evenwhenoxpeckersclimbonto mutualism in this association remains untested.
the face orinto an earpinna. Some mammals, espe-
Relationships with humans
ciallyzebra and impala, appeartosolicitcleaningby
assuming stereotypical, upright postures that make Oxpeckers have declined in numbers over much of
theirrangeduringthiscenturywith theexpansionof
human populations and their cattle into areas once
occupied exclusively by wild game. Cattle dipping
removesmanyoftheectoparasiticinsectsthatarethe
mainstay of the oxpecker diet. The great rinderpest
epidemicsattheendofthelastcenturyalsoprobably
played an important role in killing huge numbers of
buffalo, a favoured host species. The Yellow-billed
Oxpecker had, as a consequence, been extirpated
from South Africa by the second decade ofthis cen-
tury, althoughthe species has reappearedin parts of
northern SouthAfrica in the past 10-20years. There
havebeensuggestionstoreintroduceoxpeckersinto
areassuchasnationalparkswheregameanimalpopu-
lations have been allowed to increase. A successful
reintroductionwasundertaken into RhodesMatopos
National Park in Zimbabwe.
Oxpeckers roost communally during the non-
breedingseason,sometimesinassociationwithother
species of starlings, at traditional sties. While these
sitesaretypicallynaturalelementsinahabitat,suchas
trees and cliffs, theycan also includebuildings. @
Dept of Biology, University of Dayton, 300 College
Park, Dayton, Ohio 45469-2320, USA.
Red-billedOxpeckerBuphaguserythrorhynchus
MarkAndrews
Oxpeckers, the genus Buphagus.- Breitwiscb BullABC Vol3 No 1 -33
