A comment on the voice and status of Vermiculated Fishing-Owl Scotopelia bouvieri and a correction to Dowsett-Lemaire (1992) on the Maned Owl Jubula lettii

2 Pages·1996·0.84 MB·

by  Françoise Dowsett-Lemaire

Short Note
A comment on the voice and status ofVermiculated
Fishing-Owl Scotopelia bouvieri and a correction to
Dowsett-Lemaire (1992) on the Maned Owl Jubula lettii
F. Dowsett-Lemaire
n 1992 I published a paperon thevoice ofanowl Congo. The existence of this tape was previously
I
which I had identified as the Maned OwlJubula unknowntome.TheirFigure 12illustratesacallwith
lettiiforreasonsexplainedbelow.4Itappears(thanks anirregularrhythm,whichsounds(inChappuis3)like
toD. Sargeant inlitttoC. Chappuis,November1993) a rather raucous, low-pitched attempt at a double-
that it was misidentified and the species concerned note song (produced by a bird held in captivity,
was, infact, theVermiculatedFishing-OwlScotopelia probably an immature on account ofthe timbre and
bouvieri. A paper recently published by Atkinson et lack ofrhythm).
al1 reviewing knowledge on the voice of all three Ifboth ofthese song-types (often given in duet)
,
African fishing-owls including S. bouvieri, confirms and the low, raucous wail (published by Chappuis3)
thisandpromptsmetowriteacorrectiontomyearlier are uttered by S. bouvieri as all present evidence
paper. shows, then itscurrentlypresumedstatus as ascarce
Theowls,ofwhichIheardseveraldozenin 1990- bird must change intothatofanabundantspecies in
91 in the Kouilou Region of southern Congo, were certainhabitats.Theyreacheddensitiesof16duetting
neveradequatelyseenwhencalling,andplaybackof pairs/km2 in the seasonally flooded for—ests of the
the tape failed to attract one to close range. Maned Kouilou, in addition to thewailing birds ofwhich
Owlwascertainlyinthearea.Onewasseenatduskin therewasone foreverytwo pairsofduettingbirds. I
a patch ofdryland forest, where the unknown song watchedandrecordedtheauthorofthewailingcallat
was heard several times on that night and another. closerangeoveralargepoolintheMayombe(atape
Featherswerealsoidentifiedfromonewhichescaped ofwhich was spectrographed byAtkinson et al1 and
fromamistnetinfloodedforest(exactlywhereapair was unable to age the bird, who was solitary. The
ofowls producedthe unknownsongsall night), and captiveauthorofthesamecallpublishedbyChappuis3
anexperiencedhuntershotacalling/,lettiinearBena could not be aged (C. Chappuis in litt). By analogy
intheMayombe.Theidentificationofmycallingbirds withPel’sFishing-OwlScotopeliapeli(Liversedge5), it
wasbasedoncircumstantialevidence,butthishunter ispossiblethatthewailisonlygivenbyimmatures.In
certifiedthat hisbirdcalledlike the tape oftheowl I Zambia, recentlyindependent immatures(easily rec-
hadrecordedinthesameareainSeptember1990,and ognised by their plumage, which is paler than the
1believedhimashisidentificationofvarioustapesof adults’, and with a yellowish, not rufous forehead)
owlsplayedtohimcouldnotbefaulted. Incidentally, occupyterritoriesseparatefromtheadultsandwhich
someoftheowlscalledforlengthyperiods, evenfor theyadvertisewiththeirloudwailingcalls-persobs,
months, indrylandforestwhereonewouldnothave andconfirmedbymanyotherobserversincludingR.J.
expected to find fishing owls. DowsettandR.Stjernstedt.AtameS.bouvieribrought
In1991,copiesofmytapeweresenttoC.Chappuis, upasachickatBomassainnorthernCameroonisstill
C.ErardandR.Ranft.Thefirsttworepliedthattheydid only producingthewailingcall at age oneanda half
not know the authors of these calls. The song of a (pers obs April 1996).
captive female S. bouvieri recorded at Chester Zoo IntheKouilou,theauthorsoftheselower-pitched
(publishedinFigure 11 inAtkinsonetal1)issimilarto wailswereoften intermixedwiththepairsproducing
song-typeoneillustratedinFigure1ofmy1992paper, the hootingduets, inthesameareaoffloodedforest.
except that it appears lower-pitched. The middle Ifhighestdensitiesareachievedinfloodedhabitats,S.
sectionof6-8hootsfallsintherangeofvariationof4- bouvieriis nevertheless also encountered in dryland
7, occasionally more, notes heard in the forests of forest, where its food cannot be fish. The first bird I
134 - BullABC Vol3 No2 Short Note
tape-recorded in the Mayombe (and whose song is
illustrated in Figure 1 ofmy paper) was calling on a
hillside, andthestreamatthebottomwasverysmall,
onlyafewcentimetresdeepinplaces,andunlikelyto
havecontainedmuchinthewayoffish.Twomonths
latertheowlwasstillinthesamearea,callingwithits
mate. With the recent rains the valley bottom had
become rather marshy and was inhabited by large
numbers of frogs. A patch of dryland forest in Bas-
Kouilouwhere itwas heardontwo nights hadgood
populationsofbirds andbatsbut, ofcourse, no fish,
andveryfewfrogs.
Furtherinvestigations in Odzala National Park in
northern Congo in 1994-95 confirm that S. bouvieri
prefers shallow, stillwaterin pools in swamp forest.
Onceagain,thehighestnumberofowlsheardwasin
theoneextensiveareaofseasonallyfloodedforestin
thepark.Wherelocatednearbigrivers,theowlswere
alwaysinanareaofbrackishwaterandsmallswamps
onoldarmsoftheriver.RJ.Dowsett(perscomm)saw
thespeciesonceintheheadlightsofhisvehicleonthe
edgeofapoolontheroad,inanareaofseveralsquare ManedOwlJubulalettii
kilometresofdrylandforest.Thenearestsmallstream MarkAndrews
was 1 km away. It seemed likely that the owl was
huntingforfrogs,theonlyvertebratefoodinthatand References
otherpools on the road. Brosset andErard2 mention 1 Atkinson, P.W., Koroma,A.P., Ranft, R., Rowe, S.G.
that a captive S. bouvieri fed happily on chicken and Wilkinson, R. 1994. The status, identification
heads, so both birds and frogs might be alternative and vocalisations ofAfrican fishing owls with par-
foodtofish.ThetamebirdfromBomassa, mentioned ticular reference to the Rufous Fishing Owl
above, hasbeenhuntingforitselfforseveralmonths Scotopelia ussheri. Bull. ABC 1: 67-72.
andhasbeenseeneatingmice,frogsandlargeinsects 2 Brosset, A. and Erard, C. 1986. Les oiseaux des
(R. G. Ruggiero pers comm) Ercegoiloongsieforeetsticeoremspodrutenmoredn-testdedsueGsapbeocne.s.VoPla.ris1:.
Forthemoment,theconclusionisthatthesongof Societe Nationale de Protection de la Nature.
J.lettiiremainsunknown. Foranexperiencedhunter 3 Chappuis, C. 1978. LesoiseauxdeI’Ouestafricain.
to have confused it with that of S. bouvieri may Sound Supplement toAlauda. Disc 9: ALA 17 and
suggest that it is ofa similar pattern. An old wildlife 18. Societe d’etudesornithologiques, 46 rued’Ulm,
scoutIworkedwithrecentlyinOdzalaNationalPark 75230 Paris.
kneweightdifferentowlspeciesincluding/,lettiiand 4 Dowsett-Lemaire, F. 1992. On the vocal behaviour
S. bouvieri.Hedescribedtheformerassingingalsoin and habitat of the Maned Owl Jubula lettii in
duet, the song consisting ofone hoot followed by a south-western Congo. Bull. Br. Om. Club 112:
213-218
series. 5 Liversedg.e, T.N. 1980. AstudyofPel’s Fishing Owl
Acknowledgements Scotopeliapeli Bonaparte 1850 in the ‘Panhandle’
region of the Okavango Delta, Botswana. Proc. 4
I amgrateful to C. Chappuis forhiscomments and a Pan-Afr. Omitbol. Congr.: 291-300.
copy of his unpublished recordings of captive
Scotopelia bouvieri. © Rue deBois de Breux 194, B-4020 Liege, Belgium.
Short Note BullABC Vol3 No2- 135