Western Black-headed Batis Batis erlangeri: a separate species consisting of two subspecies

2005·4 MB·

by  Michel Louette

,
Western Black-headed Batis Batis erlangeri a separate
:
species consisting of two subspecies
MichelLouette
Batis erlangeri: une espece distincte composee de deux sous-especes. La distribution, la taille et
les vocalisations du taxon traditionnel Batis minor (Pririt a joues noires) suggerent que celui-ci
merited’etrediviseen deuxespecesapartentiere: B. minoretB. erlangeri. Lapluspetite, B. minor
sensu stricto, est composee de deux sous-especes: B. m. minor et B. m. suahelicus. B. erlangeri
comprend egalementdeuxsous-especes. L’examen despecimens, principalementau Musee Royal
de l’Afrique Centrale, Belgique, a en effet permis la distinction morphologique de ces deux
populations. Celledelaregionausuddelaforetequatorialeen RD Congo meridionaletleszones
limitrophes, B. e. congoensis a le bee legerement plus court que celle de la population nominale
septentrionale.
T
hegenus Batisis endemic toAfricaand com- of two subspecies, minor and suahelicus, and
prises a group of small, contrastingly Western Black-headed BatisB. erlangeri, also com-
coloured flycatcher-like birds with relatively large prising two subspecies, erlangeriand congoensis.
heads, broad bills, short legs and short tails. It is a
genus of great uniformity in general appearance Material and methods
andbehaviour. Opinionsconcerningspecies limits I studied all specimens held at the Royal Museum
havevariedgreatly: in recentworks, thenumberof for Central Africa, Tervuren, Belgium (RMCA)
recognised species has varied from 16 (e.g. Urban (minor. 2; suahelicus: 4;perkeo: 9; erlangeri: 31 and
et al. 1997, hereafter BoA; Harris & Franklin congoensis: 119) and several dozen ofothers, espe-
2000) to 19 (e.g. Sibley & Monroe 1990). The cially oftaxa less well represented in the RMCA,
systematicstudies ofLawson (1986, 1987) are not in The Natural History Museum, Tring, UK,
generallyaccepted: someauthorities have incorpo- Museum National d’Histoire Naturelle, Paris,
rated part ofhis conclusions and data (e.g. BoA, France, Naturhistorisches Museum, Vienna,
Harris & Franklin 2000), whilst others (e.g. Austria, and Zoologisches Forschungsinstitut und
Dowsett & Dowsett-Lemaire 1993) have not Museum Alexander Koenig, Bonn, Germany.
accepted his conclusions. Given the lackofmolec- Standard mensural data (flattened wing-chord,
ular research, the external morphology, ecology tail, tarsus and total culmen) were taken with rule
RMCA
and distribution (sympatry or allopatry) are and callipers forthe material. I also under-
importantin definingspecies limits amongstthese took a complete literature research and compared
extremely similar birds, and such factors, supple- dataonvoice and habitat (all references in Louette
mented by differences in voice and habitat, guid- in press).
ed me whilst preparing the Platysteiridae chapter
Zoogeography
for Handbook ofthe Birds ofthe World(Louette in
Where two or more Batis species occur together,
press). Future research in contact regions should
produce additional clues concerning some they are usually ecologically segregated by habitat
relationships. preferences. R. J. Dowsett (in litt. 2003) noted
minoBroAasanad Hsaprerciises&—BFlraanckkl-ihnea(d2e0d00)Battriesa—t Bwaittihs itnhastoamenucmasbeesrevoefnBabteiysosnpdecitehserseapmlaecesuepaercshpeoctiheesr.,
three subspecies, minor suahelicus and erlangeri. Nevertheless, B. minorsensu lato is narrowly sym-
On balance, however,, I find the differences patricwith fourofthe five paraspecies oftheBatis
between erlangeri and minor!suahelicus—sufficient [senegalensis] superspecies (named B. [molitor] in
BoA; the International Code of Zoological
to warrant recognition of two species Eastern
Black-headed Batis B. minor (named East Coast Nomenclature, fourth edn, 1999, indicates thatthe
oldest species name must be used for super-
Black-headed Batis by Jackson 1938), consisting
species), respectively Senegal Batis B. senegalensis,
WesternBlack-headedBatis:aseparatespeciesconsistingoftwosubspecies:Louette BullABCVol12No2(2005)-99
ChinspotBatisB. molitor EastCoastBatisB. soror The ranges ofthe populations ofBatis minor
,
andGrey-headed BatisB. orientalis(thefifth being sensu lato are disjunct (Fig. 1). No other bird
the extralimital Pririt Batis B. print). Thus, B. species shares a similar distribution pattern.
erlangeri seems to overlap with B. senegalensis in Because the eastern forms, minor (in southern
Cameroon (Languy submitted); although the Somalia) and suahelicus (from Kenya and
specimens listed by Good (1953) from Yaounde, Tanzania), are not in geographical contact with
BafiaandMeigangaare all erlangeri notsenegalen- the rest ofthe population, their relationship can-
,
sis. It is also known to overlap with B. molitor at notbefield-tested. PygmyBatis B.perkeooccupies
one locality, Djambala, in Congo (Rand et al. part ofthe range between erlangeriand minor/sua-
1959), at a few localities in DR Congo (Louette helicus in arid and semi-arid East Africa, where it
1987, Demey et al. 2000) and somewhat more generallyprefers drierhabitat (seehabitatcompar-
&
widely in western Kenya (Lewis Pomeroy ison). Nevertheless, given that it is vocally more
1989). B. minor over&laps with B. soror on the like B. minor, not B. molitor, and that it too is
Kenyan coast (Lewis Pomeroy 1989). Overlap locallysympatricwithB. orientalis(Zimmermanet
ofB. minorsensulatowithB. orientalisisverymar- al. 1996), B. perkeo cannot be considered part of
ginal in Kenya (see Zimmerman etal. 1996, who the B. [senegalensis] superspecies. Although B.
admit only one locality, confirmed by D. A. perkeo maybe related to either minor!suahelicusor
&
Turner pers. comm., contra Lewis Pomeroy erlangeri or to both, it is not conspecific with
,
1989), but that ofB. erlangeriwith B. orientalis is them, as it overlaps geographically (albeit margin-
claimed to be very extensive in Sudan (Nikolaus ally) with both (Fig. 1). At present, the distribu-
1987). This, however, requires further study, tion ofthe three forms, fromwest to east, western
because few specimens have been correctly identi- B. minorsensu lato B.perkeo and eastern B. minor
,
fied beyond doubt. Although the existence of a sensu lato suggests they are three separate
cline between orientalisand ‘minor (= erlangeri) in (para)species. There is no apriori reason for con-
Chad and the Central African Republic was sug- specificity ofthe western and eastern forms. It is
gested by Vielliard (1972), he, and subsequently indispensable to include all three in the analysis.
also Lawson (1987), may have been confused.
Indeed, theform minorwas originallydescribed as Voice
a subspecies of B. orientalis and the subspecies Batis erlangeri
chadensis, now in B. orientalis was placed in B. Ringing, monotonous, pure and clear penetrating
,
minor sensu lato by Rand (1953). The identifica- whistles, the pitch of each note rising. Varies
tion ofspecimens must be made with great care regionally in modulation (Zimmerman et al.
(see Zimmerman etal. 1996) and I suspect, from 1996, Dowsett-Lemaire 1997, Chappuis 2000).
the material in Vienna and Paris, that Grey-
Batis minor
headed Batis (of which the female has a more
Drawn-out, piping, high-pitched notes, usually in
brownish, not greyish tone to the neck) generally
groups of2-3, first note lower, clear and ringing.
occurs north ofthe range ofWestern Black-head- &
Slower, longer than B. erlangeri (Harris
ed Batis, probably with restricted overlap. Thus,
Franklin 2000).
the northern limit ofthe range ofWestern Black-
headedBatis (Fig. 1) mustbe considered tentative. Batisperkeo
Vocalisations seem to be oflimited importance to
Penetrating piping notes, sharper, more ringing
study relationships in Batis (F. Dowsett-Lemaire andless drawn-out than inB. minor which itsug-
pers. comm.). Their comparison (from Chappuis gests, in series ofup to 20 notes (Z,immerman et
2000) suggests nevertheless that orientalis belongs
al. 1996).
to the Batis [senegalensis] superspecies and that
Batis minorsensu lato cannot be its close relative. Habitat
The local variation in vocalisations in the latter is Batis erlangeri
&
important (Harris Franklin 2000, F. Dowsett- Secondary forest, woodland, wooded grassland,
Lemaire pers. comm.); the briefvoicecomparison, large gardens.
as deduced from the literature, is given here for
general information.
100-BullABCVol12No2(2005) WesternBlack-headedBatis:aseparatespeciesconsistingoftwosubspecies:Louette
,
Batis minor does not necessarily prove their relationship. In
WoodedsteppewithAcaciaand Commiphora also congenerics that do form a clear taxonomic unit,
;
riverine habitat (occasionally in woodland and such as the Batis [senegalensis] superspecies, such
along small watercourses in Tsavo East, Kenya). morphological uniformity does not exist (female
On Mt Endau present in semi-deciduous forest B. senegalensis have much brown dorsally and
and patches ofmist forest. female B. molitor B. soror and B. print have a
,
brown throat patch, whereas B. orientals is ‘stan-
Batisperkeo dard’). Some ofthe forest batises, such as Angola
Trees and scrub in arid regions, woodland and Batis B. minulla and Bioko Batis B. poensis also
wooded grassland. Thorn scrub, Acaciawoodland have ‘standard’ plumages.
and Commiphora country. All habitats with trees,
except riverine (competition with B. minor) in Size and plumage
Tsavo East. Tolerates arid conditions. Batis erlangeri
11 cm; 8.3-14.0 g. Male: crown and mantle dark,
Morphology normallydarkerthanB. minor jetblack, butsome
,
The form erlangeri (including congoensis\ see individuals more greyish. There is a very dark
below) is significantly larger (wing-chord being specimen (RMCA 63028), from Lusambo, Kasai,
used as a parameter for size) than minor and sua- DR Congo (Figs. 4-3). Female: breast-band
helicus', Pygmy Batis is the smallest of the genus maroon (Fig. 6).
(Figs. 2-3; Tables 1-2; for additional measure-
ments, see Lawson 1987). Batis minor
Compared to minorand suahelicus, erlangeriis 10 cm; 9.3-13.8 g. Male m. minor, crown and
also darker on the mantle, but less blackon top of nape blackish or dark grey (crown colour easily
thehead. Femaleshave moreolivewash. However, confused with B. orientalis m. suahelicus: head
);
variation in plumage details between specimens of greyer black. Female m. minor, breast-band dark
the same population is occasionally considerable, chestnut, dorsally tinged brown/olivaceous; m.
sometimes being as great as that between species. suahelicus breast-band narrower.
This is the case for the darkness of the crown in
Batisperkeo
the group under discussion here.
The conventional grouping of all ‘black- 8-9 cm; 3-9 g. Male: forehead, crown and back
headed’ batises into asinglespecies, B. minorsensu bluish grey; top ofhead less black than B. minor
but mantle generallydarker. Female: washed more
lato, is perhaps because all exhibit the ‘standard’ olive than B. minor, dorsally paler and browner;
Batisplumagepattern, consistingofablackbreast-
bandinmalesandabrown breast-band in females. supercilium, throat and, in some, neck tinged
This, however, may be due to coincidence and rustyoryellowish; breast-band rufous or buff, not
deeply saturated.
Table 1. Mean ofmeasurements (in mm) ofthewing of Geographical variation
adultBatisspp. specimens in RMCA: samples(n). Batis erlangeri
Tableasupe1c.iMmoeynesnandeuldteessmdeensBautriastisoppn.sa(ummM)RAdeC.I’ailede TeqhueatoirsioallatefdorpeostpuliantisoonutohcecrunrriDnRg sCouotnhgoofatnhde
neighbouring countries (Fig. 1, see details in
n Wing-chord Louette 2005) was described as subspecies con-
Males goensis by Neumann (1907), based mainly on the
B.perkeo 4 51.3 paler grey back of the female. Other subspecies
B.m.minor 1 53.5 (nyansae and hatesi) have been proposed, but I
B.m.suahelicus 2 55.0 consider the limited material I have seen indistin-
Females
guishable. Chapin (1953) accepted congoensiswith
8.perkeo 4 51.0 misgivings, ‘the status of B. m. congoensis seems
B.m.minor 1 53.0 very doubtful’ (p.66l) and ‘I very much doubt
B. m.suahelicus 2 54.3
that B. m. congoensis can really be distinguished
WesternBlack-headedBatis:aseparatespeciesconsistingoftwosubspecies:Louette BullABCVol12No2(2005)-101
1
102-BullABCVol12No2(2005) WesternBlack-headedBatis:aseparatespeciesconsistingoftwosubspecies:Louette
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Figure 1. DistributionofBatise. erlangeri(red), B. e.
congoensis(green), B. minor(blue) andB.perkeo (yellow).
LarepartitiondeBatise. erlangeri(rouge), B. e. congoensis
(vert), B. minor(bleu) etB.perkeo (jaune).
Figure2.Ventralviewofspecimens of(fromleftto right
andfrom topto bottom) Batisperkeo, B. m. minor, B. e.
congoensisandB. e. erlangeri(Alain Reygel). © Royal
MuseumforCentralAfrica,Tervuren, Belgium
VueventraledespecimensdeBatisperkeo, B. m. minor
,
B. e. congoensisetB. e. erlangeri(degaucheadroiteetde
hautenbas) (Alain Reygel). © RoyalMuseumfor
CentralAfrica,Tervuren, Belgium
Captions continuedonpage 104
WesternBlack-headedBatis:aseparatespeciesconsistingoftwosubspecies:Louette BullABCVol12No2(2005)-103
Table2. Measurements (in mm)ofthewing, tail, culmen andtarsusofadultBatiserlangerispecimens in RMCAfrom DR
Congo: samples (n). Mean ±standard deviation. Mann-Whitneystatistical comparisons between northern (= north ofthe
equatorialforest) B. e. erlangeriand southern (= south oftheequatorialforest) B. e. congoensispopulations.
Tableau 2. Moyenneetdeviation standard des mensurations(mm)de I’aile, de la queue, du culmen etdutarsedespeci-
mensadultes provenantde la RD CongodeBatiserlangeriau MRAC. Comparaison statistique Mann-Whitneyentre les
populationsdu nord de laforetequatoriale (B. e. erlangeri) etdecellesdu sud de laforetequatoriale (B. e. congoensis).
n Wing-chord Tail Culmen Tarsus
Males
B. e. erlangeri 18 59.8+ 1.8 42.4±1.5 13.0±0.4 16.4±0.9
B. e. congoensis 32 59.9±1.6 40.8±1.2 12.4±0.5 15.5±0.7
U-tests:P-levels .7541 .0005 .0007 .0033
Females
B.e. erlangeri 19 58.1 +1.5 40.3±1.1 12.7±0.5(18) 15.1 ±0.7
B. e. congoensis 33 58.8±1.3 40.3±1.1 12.2±0.5(32) 14.9±0.6
U-tests:P-levels .0964 .9243 .0045 .4586
from nyansae...ln size theyare equal, and I cannot goensis. However, as birds ofthis population have
confirm the statement by Neumann that females a statistically significant shorter bill and shorter
ofcongoensis are clearer gray above’ (p.663). BoA tail (in males only) than those of the northern
&
and Harris Franklin (2000) did not accept con- population (Table 2), I here restore this sub-
species. The biological meaning of these differ-
ences is unknown. They are sufficiently small not
ceptions to figures onpage 103 to suggest a difference at species level.
Figure3. Dorsalviewofspecimens of(fromleftto right Batis minor
aconndgofernsoimstaonpdtBo.boe.tteorlma)ngBeartiis(AplearikneoR,eyBg.elm)..m©inoRro,yaBl. e. The suahelicus population differs from the nomi-
MuseumforCentralAfrica,Tervuren, Belgium nate race in having a greyer black head and a nar-
VuedorsaledespecimensdeBatisperkeo B. m. minor B. rower breast-band in the female. This difference is
e. congoensisetB. e. erlangeri(degauche,adroiteetde, considered to be small and not attaining species
hautenhas) (AlainReygel). © RoyalMuseumfor level.
CentralAfrica,Tervuren, Belgium
RMCA Batisperkeo
6Fi3g0u2r8ef4.roVmenLtruaslavmibeow(olfefat)bearnrdantnomramlael’spBeatciismee.ncongoen- No variation described.
sismale (right) (Alain Reygel). © RoyalMuseumfor
CentralAfrica,Tervuren, Belgium Conclusion
Vueventraleduspecimen aberrantMRAC 63028 de Distribution ofthe batises (and ofbirds in gener-
B(aatdirsoie.tec)on(gAoleanisnisRe(yaggealu)c.h©e)Reotyda’luMnusspeecuimmefnor«Cneonrtmraall » salu)ggienstnotrhtaht-cBe.ntrmailnoAfrriscean,susizleatoanmderviotcsaldiisvaitsiioonns
Africa,Tervuren, Belgium
into two species. Specimen mensural data more-
RMCA
Figure 5. Dorsalviewofaberrantmalespecimen over provide sufficient evidence to consider B.
s6i3s0m2a8lef(rroimghtL)us(AalmabinoR(elyefgte)l)a.nd©‘nRoorymaall’MBuastiesuem. cfoonrgoen- erlangeri (which is larger than B. minorsensustric-
CentralAfrica,Tervuren, Belgium to) as comprising two subspecies. Especially the
VuedorsaleduspecimenaberrantMRAC63028 de bill is, in series, smaller in the population south of
Batise. congoensis(agauche) etd’unspecimen « normal» the equatorial forest in south-west DRCongo and
(adroite) (Alain Reygel). © RoyalMuseum forCentral adjoining areas (subspecies congoensis than in the
)
Africa,Tervuren, Belgium nominate northern B. e. erlangeripopulation.
Figure 6. FemaleofWestern Black-headedBatis Batis
erlangerion its nestin Cameroon (RogerFotso) Acknowledgements
LafemelledeBatiserlangerisurson nidauCameroun I thank the following curators: Robert Prys-Jones
(RogerFotso) (Tring), Eric Pasquet (Paris), Ernst Bauernfeind
104-BullABCVol12No2(2005) WesternBlack-headedBatis:aseparatespeciesconsistingoftwosubspecies:Louette
(Vienna) and Renate van den Elzen (Bonn), as well Lewis, A. & Pomeroy, D. 1989.A BirdAtlas ofKenya.
as Marc Languy and Don Turner for their com- Rotterdam:A.A. Balkema.
ments. Ron Demeysuggested that I write this paper Louette,M. 1987.Additionsandcorrectionstotheavi-
and he, Franchise Dowsett-Lemaire and Robert fauna of Zaire. Bull. Br. Ornithol. Club 107:
Dowsett suggested corrections to its draft. Alain 137-143.
Reygelassistedmyexaminationofspecimens, andhe Louette, M. 2005. Conservation priorities and geo-
and Danny Meirte prepared the map. Roger Fotso graphical variation In Huber, B. A., Sinclair, B. J.
photographed the bird in Cameroon. & Lampe, K.-H. (eds.). Afican Biodiversity.
Molecules, Organisms, Ecosystems. New York:
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