Systematics, distribution and vocalisations of Papyrus Yellow Warbler Chloropeta gracilirostris

7 Pages·2003·4 MB·

by  Ilya M D Maclean

1
Systematics, distribution and vocalisations of
Papyrus Yellow Warbler Chloropeta gracilirostris
IlyaMaclean* John Musinab NicodemusNalianyab Simon Mahood*, RobMartina
, , ,
andAchilles Byuaruhangac
Les auteurs analysent la systematique du Chloropete aquatique Chloropeta gracilirostris et
presentent quelques notes supplementaires sur son apparence et ses vocalisations. Cette espece
comprend deux ou trois populations isolees. Le taxon actuellement considere comme la sous-
espece nominale est connu principalement de lavallee du Rift albertin et de quelques marecages
au Kenya occidental. C. g. bensoni n’est connu que de la Luapula en Zambie et en Republique
DemocratiqueduCongo.IIaetesuggereauparavantquelapopulationduKenyaestspecifiquement
distinctedes deuxautres, lesspecimens decettepopulation detenus dans les museesayantun bee
considerablementplusetroit. Ceci n’esttoutefoispasconfirmeparlesmensurations prisessurdes
oiseaux vivants. Neanmoins, les vocalisations de chaque population semblent differer. Des
conclusions quantal’isolementgenetiquedeces populations nepeuvent toutefoisetre proposees
sans de plus amples recherches.
identification features in the hope that future
attention will be focused on the species and its
protectedbirds in EastAfrica9. Its habitat is under taxonomic status be clarified.
increasing threat: extensive swamp drainage has
occurred to grow crops and, more recently, to Distribution and habitat
permit dairy farming. Existing swamps are often Papyrus YellowWarbler is endemic to swamps in
encroached by farmers or degraded by over- East and Central Africa. Some confusion exists
harvesting ofpapyrus, which is used as fuel or in overthedistributionofwhatiscurrentlyconsidered
&
localcrafts.Theseproblemshavebeencompounded to bethe nominate race. Irwin Turner11 suggest
bythecollapseofLakeVictoriafisheriesasaresult that itpersists in twowidelydisjunctpopulations,
oftherapidinvasionofWaterHyacinthEichhornia whereas Urban etaPconsiderthatitsdistribution
crassipes forcinglocalpeopletoseekotherformsof iscontiguous.Inreality,thesituationisnotcertainly
,
livelihood. Elsewhere, a shortage of productive established. Itiswellknownfromseverallocalities
land as a result of rapid population growth has in theAlbertine Rift, with a stronghold in south-
resulted in the same problem. Often the only westUganda,RwandaandnorthernBurundi.This
alternative is to cut papyrus or to reclaim swamps form has also been recorded from swamps on the
to grow crops. westernborderofTanzania(withRwanda/Burundi)
Currently, Papyrus Yellow Warbler is and two areas in the eastern Democratic Republic
considered globally threatened and categorised as of Congo8,19,20. A second population of C. g.
Vulnerable4 However, arecentreviewofmuseum gracilirostriswasdiscoveredinKenyainthe 1960s6
. ,
specimenspromptedthesuggestionthattwospecies whereitisknownfromLakeKanyaboliandnearby
maybeinvolved1 andthatthepopulationendemic Yala swamp and several swamps on the Kenyan
,
towesternKenyaisprobablyCriticallyEndangered. (northern) shore ofLake Victoria2. At the time of
Itshabitatinwestern Ugandais also underserious the discovery, itwas assumed that the birdwould
threat7 Given the difficulties in observing these subsequentlybeprovedtohavealargelycontinuous
.
secretive birds in dense stands of papyrus, distribution between Kenya and south-west
comparatively little is known about them. We Uganda. However, the species appears to have a
reviewcurrent knowledge ofthe taxonomic status spottydistribution in eastern Uganda, with single
and distribution ofthe species, and present notes sight records from Lake Mburo16, Lake Nakuwa7,
on the appearance and vocalisations of those LutembeBay7andMakokobeswamp, butatthese
observedinsouth-westUgandaandwesternKenya locations it appears to be less common than
in July-August 2002. We also outline the key elsewhere. Despite extensive searches of those
94-BullABC Vol 10No2 Systematics, distributionandvocalisationsofPapyrus Yellow Warbler:Maclean etal
6
1
described the following year, is a synonym of
n
hensoni
.
The Zambian and Kenyan populations are
apparentlyconfinedtopapyrus. IntheYalaswamp
complexofKenya,PapyrusYellowWarblerprefers
tall, undisturbed papyrus, particularly nearwater,
and is absent from smaller, more isolated swamp
fragments (O Nasirwa pers. comm.). In contrast,
thewesternpopulationisnotrestrictedtopapyrus,
occurring most frequently in mixed patches of
papyrus and otherwetlandvegetation. Ithas been
suggested that this is only true at altitudes above
1,300 m, below this the species being excluded
from other types ofwetland vegetation through
competition with African Reed Warbler
Acrocephalus baeticatus which is absent at higher
,
altitudes20 InUganda,wefoundthetwocoexisting
.
inCladiumswampsat1,300m.Moreover,Papyrus
Yellow Warbler occurs in many small, disturbed
marshes that fringe lakes in south-west Uganda.
6)
Taxonomy
I7t)has recentlybeen suggested that the population
in western Kenya is specifically distinct from that
intheAlbertineRift1 basedonthemuchnarrower,
,
moreAcrocephalus-likebilloftwospecimenstaken
in Kenya6 We have examined one ofthese, in the
.
National Museums ofKenya (Nairobi), a female
collected by Peter Britton at Lake Kanyaboli on 8
(NMK We
Figure 1. Distribution ofthe threepopulations of June 1969 832). consider that this
PapyrusYellowWarbler Chloropetagracilirostris. Solid bird’sbillmayhavebeenpinchedbyover-tightening
squares indicateconfirmedrecords andopensquares the twine around the bill during preparation (Fig
unconfirmed records. a possibility supported by field measurements
,
ofonewetrappedatLake Kanyaboli,whichhada
considerably broader bill than the specimen (Fig
swamps fringing LakeVictoria, we found none in However, subtle plumage differences between
.
easternUganda,althoughamorewidespreadsearch, those we observed in Kenya and in the Albertine
particularly in the Lake Kyoga basin, may clarify Riftand, moreimportantly, totallydifferentsongs
theextenttowhichthetwopopulationsareindeed lead us to suspect that the two populations may
disjunct. It is also noteworthy that the similar indeed constitute species or at least subspecies.
African Yellow Warbler Chloropeta natalensis Recordings ofthe Zambian population and more
frequently occurs at the edges ofpapyrus swamps distinct plumage differences between this
and represents apotential identification pitfall for populationandtheothertwosuggestthatitmaybe
inexperienced observers.
specifically distinct.
Asecond subspecies, C. g. hensoniAmadon1 is
knownonlyfromLakeMweruatthemouthofthe Description
Luapula River in Zambia and from Nkole in C. g. gracilirostris (Kenya)
adjacent Democratic Republic ofCongo (Fig 1). Adult: sexes alike. General structure, apart from
Although this population has been known since the bill, recalls that of a short-winged, slightly
1938,itwasnotaffordedtaxonomicstatusuntil 1 heavily builtAcrocephaluswarbler (Fig 8). Crown
years later. C. g. bredoi Schouteden17 from Nkole, to hindneck and ear-coverts olive-brown with a
Systematics, distributionandvocalisationsofPapyrus Yellow Warbler:Maclean etal BullABC Vol 10No2-95
slight greenish wash, grading into a more rufous rump. Both lackolive tone to head and mantle of
olive-brown, lacking the greenish tinge on the Kenyan birds. As in the Kenyan population,
mantle and rump. Tail darker brown and inner underparts warm yellow but flanks and undertail-
rectrices longer than the outer ones. Secondaries coverts slightly less tawny-ochre than in Kenya.
and coverts a similar dark brown. The one we Warm yellow neck, breast and undertail-coverts
trapped had paler fringes to the feathers, but this contrastwithpaleyellowthroat.Contrastgenerally
mayhavebeenaresultofwear.Underpartswarmish more distinctive and clear-cut than in the Kenyan
yellow,washedtawny-ochreonflanksandundertail- population, contrastingwith both underparts and
coverts (Fig 5). Upper breast contrasts with paler olive-brown ear-coverts. Legs and feet dark grey
yellow throat, although this is onlyevident under and claws long. Bill similar to that ofthe Kenyan
certain light conditions. Red iris contrastingwith population, having a dark grey upper mandible
paler eye-ring and blackpupil. Legs and feet dark andpinkishlowermandible.Mensuraldatasuggest
grey,withlongclawsadaptedforclaspingpapyrus. thatthebillmaybeslightlybroader. Eyesimilarto
&
In contrast to Irwin Turner’s11 suggestion, the
bill of the one we trapped was characteristically
Chloropeta-like (Fig 7.) and considerably broader
than depicted in Urban etaP (see Table 1). The
grey upper mandible contrasts with a paler, more
pinkish lower mandible. Descriptions and
&
illustrationsinStevenson Fanshawe18andUrban
etaP are almost certainlyofKenyan birds.
Immature: readilydistinguishablefromadults,
beingtawnierbelow,andpossessingapaleririsand
paler throat with some whitish buff. The gape is
yellowish as opposed to bright orange and young
have tongue spots.
02 04 06
C. g gracilirostris (Albertine Rift) Time in seconds
Adult: plumage differences between those we
observed at Lake Bunyonyi in south-west Uganda
andatLakeKanyaboliinwesternKenyaaresubtle. Figure2. Threephrases ofPapyrusYellowWarbler
Basedonourobservations, thepopulationappears Chloropetag.gracilirostrisrecorded at Lake Kanyaboli,
moreuniformdullbrownonthemantle,rump,tail wTeescthenrincaKeAnTy8a.35RbecmoircdriongphboyneJManudsianSgoanAyuMdiWo--750V
andwing-coverts than birds in Kenya. Head dark
cassetterecorder. Sonogramsprepared using
brown, contrasting with paler brown mantle and SpectrogramVersion 2.3 software.
Table1.Comparisonofmeanbillandwingmeasurements(mm) (tS.D. whereavailable)
ofPapyrusYellowWarblerChloropetagracilirostris.
Taxon Location Number Culmen Billbreadthatnostrils Wing
C. g.gracilirostris11''12 Albertine Rift 4 16.0 6.1 61.5
C. g. gracilirostris11 Lake George 1 15.5 6.0 nodata
C.g.gracilirostris11 Lake Kanyaboli 2 16.0(+0.00) 3.0(+0.00) nodata
C.g. gracilirostris^ Lake Kanyaboli 9 nodata nodata 61.6 (+2.35)
C. g.gracilirostrisf Lake Kanyaboli 77 nodata nodata 62.3 (+2.37)
C. g. gracilirostris^ LakeSare 2 nodata nodata 62.5(+0.71)
C. g. gracilirostrisr Usenge 1 nodata nodata 62.3
C. g. gracilirostris Lake Kanyaboli 1 15.1 5.1 59.0
C.g. bensoni"’’12 Lake Mweru 1 15.5 5.0 54
C.g. bensonN Lake Mweru 1 15.0 5.5 nodata
'Basedonfield measurementsofoneatLake Kanyaboli inAugust2002.
fBasedonfieldmeasurementstaken byOliverNasirwafrom Lake KanyaboliandYalaswamp
96-BullABC Vol 10No2 Systematics, distributionandvocalisationsofPapyrus Yellow Warbler:Maclean etal
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A) 10 andslightlypalergreybillandlegs1 .Aphotograph
&
ofthis form is included in Leonard Beel14 and
suggeststhattheunderpartsaremuchpaleryellow,
although this could be attributed to lighting
Hertz conditions. Bill measurements are very similar to
in those obtained from the Kenyan bird we trapped
(Table 1).
Frequency
Vocalisations
C. g. gracilirostris (Kenya)
The bird has three main phrases, each ofwhich is
reproduced in—Fig 2.
Timeinseconds A. Cotcheeow aslightlymetallicwhistlerepeated
every c3 seconds.
—
B ChoweetChoweet twoalmostidenticalmetallic
Figure3. FourphrasesofPapyrusYellowWarbler . whistles repeated every 3.3-4.0 seconds.
Chloropetag gracilirostrisrecordedatLake Bunyonyi, —
south-westUganda. RecordingbyAB usingaSennheiser C. Cheeowow ascratchierless sibilantnote than
MKE300 directional microphone andaSonyTCM- (A) repeated every 3-4 seconds.
5000EVcassetterecorder. Sonograms preparedusing
SpectrogramVersion 2.3 software.
C. g. gracilirostris (Albertine Rift)
Fourmainphrases, eachofwhichis reproducedin
Fig 3- —
A. Gwogwogwogwogwo aseriesof4-3 sibilant
notes uttered every 4-7 seconds.
—
Hertz B. Brob brob chrip chrip a series offour rattling
in notes, the first two slightly quieter and lower
pitched, repeated every 2-4 seconds.
—
Frequency C. Cotrrrrrrrreel aquicknotefollowedbyarapid
slightly higher pitched trill, typically uttered
every 3-4 seconds, although gaps ofup to 15
seconds may ensue. Males and females often
utter this phrase in succession.
D. A variation on (C) involves a more sibilant
Timein seconds dotdweelrepeatedevery2-3 seconds, although
Figure4. FourphrasesofPapyrusYellowWarbler longer gaps can ensue.
Chloropetag. bensonirecordedatthe LuapulaRiver,
Zambia. RecordingbyBob StjernstedtusingaAKG C. g. bensoni
microphonewitha30" parabolaandaPhillips cassette Fourmainphrases, eachofwhichisreproducedin
recorder. SonogramspreparedusingSpectrogram
Version 2.3 software. Fig4. —
A. Thweet-slow-wheee a three-part musical
phrase,thecentralpartofwhichislowerpitched.
—
thatoftheKenyanpopulation: rediriscontrasting B. Phwit-slrlrlrl-ow a three-part musical warble,
with paler eye-ring and blackpupil. the middle part a higher pitched trill.
Immature: unknown. —
C. Ts-lrlrlrleeow asimilarphraseto(B)butlower
pitchedandlackingthefirstpartofthephrase.
C. g. bensoni —
D. Putdrrrrrreel similar to phrase (D) of the
Differs from the nominate principally in lacking
anyrufous or ochrewash to the flanks, rump and Albertine Rift population, but higher pitched
tail1,19.ItappearstobesmallerthanC.g.gracilirostris, and less sibilant.
hasapaleyellow1 orwhite14ratherthanreddishiris
Systematics, distributionandvocalisationsofPapyrus Yellow Warbler:Maclean etal BullABC Vol 10No2-97
1
Figure 5. PapyrusYellowWarbler Chloropetag. Figure6. PapyrusYellowWarbler Chloropetag.
gracilirostrisspecimen inNational Museums ofKenya, gracilirostrisatLake Kanyaboli, Kenya, showingthe
Nairobi (NMK852); notethetwinearoundthebill, characteristically Chloropeta-like bill (Rob Martin)
whichcouldberesponsible forcompressingit (Rob
Martin)
Figures7-8. PapyrusYellowWarbler Chloropetag.gracilirostris, Lake Kanyaboli,western Kenya (Rob Martin)
Callshavealsobeendescribedas(A) To-tslo-wee(B) slightly narrower than that of the Albertine Rift
Teeu-tschlee-wo (C) Tslo-tschlee-wo and (D) Tsclee- population of C. g. gracilirostris, but all are
ow or as a musicalpee,p-r-r-r (eeas in sweet)3. characteristicallyChloropeta-Y\kzanddonotappear
todiffertotheextentsuggestedbyIrwin&Turner1 .
Conclusions Though the bill of Papyrus Yellow Warbler,
Though we agree with Irwin & Turner11 that the irrespective of population, is narrower than its
KenyanpopulationofC.g.gracilirostrismaywarrant congeners, this is a diagnostic feature ofpapyrus-
taxonomic recognition, our reasons are quite dwelling passerines12
.
different. The bill widths ofC. g bensoni and the Thedistribution ofPapyrusYellowWarbleris
Kenyan population of C. g. gracilirostris may be poorly known, and further research should
98-BullABC Vol 10No2 Systematics, distributionandvocalisationsofPapyrus Yellow Warbler:Macleanetal
endeavourto clarifythespecies’ taxonomy. Under 5. Britton, P.L. 1978. Seasonality, densityand diver-
the Biological Species Concept, it is difficult to sityofbirdsofapapyrusswamp inwesternKenya.
determinethetaxonomicstatusofallopatrictaxa11 Ibis 120: 450-466.
.
TheextenttowhichtheKenyanandAlbertineRift 6. Britton, P.L. and Harper J.F. 1969. Some new
populations or, indeed, C. g. bensoni might be distributionalrecordsforKenya.Bull.Br. Ornithol.
considereddistinctunderthePhylogeneticSpecies Cl. 89: 162-165.
Concept is uncertain, and awaits analysis oftheir 7. Byaruhanga,A.,Kasoma,P.andPomeroy,D.2001.
molecularphylogeny.Nevertheless,ourrecordings Important Bird Areas in Uganda. Kampala:
NatureUganda.
of the songs of the Kenyan and Albertine Rift
pdiofpfuelraetntiofnrsomofeaCc.h ogt.hegrracainldirofsrtorimsCa.pgpeabrensvoenriy 8. TCaursshwaeblel,, MH..,inPopmreersso.y,ADB.iEr.d, ARtelyansoflodrs,UgJ.anadnad.
, Tring: British Ornithologists’ Club.
and we encourage other recordists to acquire
9. Fanshawe, J.H. and Bennun, L.A. 1991. Bird
additional samples ofthis species’ vocalizations to
conservationinKenya: creatinganationalstrategy.
adequately assess the extent to which these
BirdConserv. Intern. 1: 293-315.
differences mayrelateto dialecticalvariationorbe 10. Irwin,D.E.,Alstrom,P.,Olsson,U.andBenowitz-
smoonrgeassuabsctoamnptilaelmaenndtitmoptorratdaitnito.naTlhmeorrpehloelvaongciecaolf PFhryeldleorsiccokpsu,sZ.(OMl.d2W0o0r1l.Cdrylpetaficwasrpbelceiress)i.ntIhbiesge1n4u3s:
studies in assigning species rank has been widely 233-247.
acknowledged among taxonomists in recent years 11. Irwin, M.P.S. and Turner, D.A. 2001. A
(IrwinetaPandreferencescitedtherein). Inother contributiontothesystematicsofthePapyrusYellow
warbler groups, songs are considered of primary Warbler Chloropeta gracilirostris. Honeyguide 47:
importanceintaxonomy10andonthisbasis,that of 201-203.
the Papyrus Yellow Warbler warrants further 12. Keith, S. and Vernon C. 1966. Notes on African
investigation. warblers ofthe genus Chloropeta Smith. Bull. Br.
Ornithol. Cl. 86: 115-120.
Acknowledgements 13. Leisler, B. and Winkler, H. 2001. Morphological
We thank Alfred Owino and other staff and convergenceinpapyrusdwellingpasserines. Ostrich
volunteers from the National Museums ofKenya Suppl. 15: 24-29.
for much useful information and logistical help. 14. Leonard, P. and Beel, C. 1999. Two newresident
BobDowsett,Fran^oiseDowsett-Lemaire,Lincoln birds in northern Zambia. Bull. ABC6: 56-58.
Fishpool and Derek Pomeroy provided useful 15. Ogilvie-Grant, W.R. 1906. New species from
feedback on drafts of the manuscript. Bob Ruwenzori. Bull. Br. Ornithol. Cl. 19: 32-33.
SCthjaerrlniseteWditlloifafmesre(dRaSPrBe)coprrdoivnigdeodftCh.eeg.qubiepnmseonnit, 16. BRiorsdssoiunw,UgJa.nadnad.SKaacmcphia,laM:.U1g9a9n8d.aWThoeurreisttoBWoaatrcd.h
fOolrivaerreNcaorsdiirnwgaobfioCme.gt.rgircacsiloifrobsitrrdissicnauUgghatnadtaLaanked 17. SecnhovuatnedReun,anHd.a-19U5r5u.nDdie,VoVgIeIl.svPaanssBeerligfiosrcmheCson(g2)o.
Kanyaboli, as well as comments on a draft. (% Ann. Mus. Roy. CongoBeige, Sci. Zool., Ser. IV(4):
329-330.
R1.efAemraednocne,sD. 1954. A new race of Chloropeta 18. SthteevBeinrsdosn,ofT.EaasntdAfFraincsah.aLwoe,ndJ.on2,00U1K.:FieTl.dG&uiAd.eDt.o
Poyser.
gracilirostrisOgilvie-Grant. Ostrich25: 140-141. 19. Urban, E.K., Fry, C.H. and Keith, S. (eds) 1997.
2. Bennun,L.A.andNjoroge,P. 1999.ImportantBird BirdsofAfrica.Vol5.London,UK:AcademicPress.
AreasinKenya.Nairobi:EastAfricaNaturalHistory
20. Vande-weghe,J.-P. 1981. L’avifaunedespapyraies
3. SBoecnisetoyn., C.W. 1956. A contribution to the au Rwandaetau Burundi. Gerfautl1: 489-536.
ornithologyofnorthern Rhodesia. Occ. Pap. Natl. aCentre for Ecology, Evolution and Conservation,
Mus. S. Rhodesia2IB: 1-51. UniversityofEastAnglia, NorwichNR47TJ, UK.
4. BirdLife International. 2000. Threatened Birds of bOrnithologyDepartment,NationalMuseumsofKenya,
&the World. Cambridge, UK: BirdLife International POBox40658, Nairobi, Kenya.
Barcelona: Lynx Edicions.
cNatureUganda,P. O. Box27034,Kampala, Uganda.
Systematics, distributionandvocalisationsofPapyrus Yellow Warbler:Maclean etal BullABC Vol 10No2-99
Appendix 1. Listofplacenamesmentioned inthetext.
Place Country Coordinates Place Country Coordinates
Albertine Rift various 01°20’S 29°30’E LakeVictoria various 01°00*S 33°00’E
Lake Bunyonyi Uganda 01°17’S 29°55’E LuapulaRiver Zambia/
LakeGeorge Uganda 00°00’S 30°13’E DemocraticRepublicofCongo 09°26’S28°33’E
Lake Kanyaboli Kenya 00°03’N 34°10’E LutembeBay Uganda 00°12’N 32°34’E
LakeMweru Zambia/ Makokobe Swamp Uganda 00°10’N 32°21’E
DemocraticRepublicofCongo 08°55’S 28°45’E Nkole DemocraticRepublicofCongo 09°26'S 28°33'E
LakeMburo Uganda 00°40’S 30°56’E Usenge Kenya 00°03’S34°02’E
LakeNakuwa Uganda 01°10’N 33°28’E YalaSwamp Kenya 00°03’N34°05'E
LakeSare Kenya 00°02’S 34°03’E
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