The Seychelles Magpie Robin: first steps on the road to recovery

4 Pages·1996·2.1 MB·

by  Neil Mcculloch

The Seychelles Magpie Robin:
first steps on the road to recovery
NeilMcCulloch
T'hepredominantlyAsiangenusofchatsCopsychus,
which includes the familiar Shamas and Indian
Magpie Robin Copsychussaularis, also contains two
speciesoccurringintheAfro-Malagasyregion. These
aretheMagpieRobinsofSeychellesandMadagascar.
Whilethelatterspeciesremainscommoninarangeof
habitats6the Seychellesspecies, C.seychellarum the
,
largest of the genus, is currently one of the most
endangeredbirdsintheworld1 Oncereducedtoonly
.
arounda dozen individuals on 210 ha Fregate Island
the Seychelles Magpie Robin is staging an encourag-
ingrecoveryasaresultofarescueprogrammebeing
carried out by BirdLife International in collaboration
with the Seychelles Government and the owner of
Fregate.
Itisknownthatattheonsetofcontinuoushuman AdultmaleaStesyocnheglpleerscMha,gFprieegaRtoeb(iNneiCloMpcsCyuclhluoscshe)ychellarum
settlement ofthe Seychelles archipelago in 1770 the
MagpieRobinoccurredonatleastsevenofthecentral could be found3 At that time cats had recently been
.
granitic islands2. It is highly likely that the species introducedtothepreviouslypredator-freeislandand
inhabited all the granitic islands with tall forest but theseweretohaveadramaticeffect.Acensusin 1965
earlybiologicalrecordsarescarce. Theoriginalhabi- couldonlyfindeightMagpieRobinsanditisunlikely
tatoftheMagpieRobinappearstohavebeenmature that theworld population exceeded 12 birds8. Fortu-
coastalforestwheretheclosedcanopymaintainedan natelyacombinationofcontrolmeasuresanddisease
open, unvegetated leaf-litter in which the birds for- greatlyreducedthecatpopulationandMagpieRobin
aged for invertebrates and small reptiles. The large numbersrecoveredto41by197810 Soonafterthisthe
.
trees also provided holes fornestsites. catswere finally eradicated.
Havingevolved inanenvironmentfreeofterres- Despite the removal of the cats the hoped for
trial mammals the extremely confiding and furtherincreaseintheMagpieRobinpopulationfailed
predominantly ground-dwelling Magpie Robin was to materialise. This situation was entirely due to the
extremely vulnerable to the cats and rats which ar- degraded state of the woodland habitat on Fregate.
rivedwiththeearlyhumancolonists.Theintroduction Around 200 years of plantation agriculture had re-
ofmammalian predators and the clearance offorest sulted in the removal of 95% of the islands natural
for plantation agriculture led rapidly to the species vegetation.Theremaining,predominantlyexotic,tree-
extinction on several islands. cover produced a leaf-litter which supported few
By 1880the MagpieRobin had disappearedfrom native invertebratesandmuchoftheislandwasuna-
thelargestisland,Mahe.Thespeciessurvivedintothe vailable forforaging because ofthe development of
early years of the twentieth century on Marianne, thick undergrowth. The relatively small plantation
Aride and Fregate, as did an introduced population trees also providedfewgoodnestsites.
established around 1890 on the coralline island of The Fregate population of Magpie Robins de-
Alphonse7. During the following fifty years the pended heavilyonthe management ofthe island for
Marianne, Aride and Alphonse populations all suc- coconutproduction. Regularcuttingofgrassbeneath
cumbedtopredatorsandhabitatdestruction.Thisleft thecoconutpalmstofacilitatecollectionoffallennuts
onlythe birds on Fregate. maintained a short sward on which the birds could
forageandthepresenceofarelativelylargeworkforce
Magpie Robins on Fregate island ontheislandresultedinthecultivationofasubstantial
ThefirstestimateofthenumberofMagpieRobinson area ofvegetable gardens where the Magpie Robins
Fregatewas not made until 1959when only 20birds could obtain invertebrates from freshly turned soil.
Seychelles Magpie Robin: McCulloch BullABC Vol3 No2-81
Coconut palms also provided alternative nestsitesin
their crowns but these were often unproductive be-
cause of predation of eggs and chicks by arboreal
nativereptiles,whicharecommonamongstthefronds,
and by introduced Indian MynasAcridotherestristis.
In this situation adult Magpie Robins were able to
survive but they nested relatively infrequently and
unsuccessfully. Recruitment was barely sufficient to
compensate for mortality.
Thesituationworsenedafter 1982whencoconut
production became uneconomic and the Fregate
plantations were virtually abandoned. This led to
encroachmentofdenseherbaceousgrowthunderthe
palms and in most of the formerly cultivated areas.
Theresultwasalossofapproximately50%ofthemost Juvenile(front)andadultSeychellesMagpieRobinstaking
productiveforagingareasandtheMagpieRobinpopu- cockroachesfromfeedingtable,Fregate(NeilMcCulloch)
lationunderwentacorrespondingdecline. Inthelate
1980s numbers averaged around 20 individuals. of the existing habitat9 There were then 22 Magpie
.
Robins.
The Recovery Programme The recovery project aims to increase Magpie
Itwasobviousthatthesituationhadreachedacritical Robin numberson Fregate usingtechniquesthatwill
stageandthatrelativelysmall-scalelocaleventscould enable a largerpopulation to be self-sustaining. The
precipitatetheextinctionofthespecies.Itwasequally initial increase is being promoted by provision of
evidentthattherehabilitationofabirdwithaverylow supplementaryfoodandartificialnestsitesthatcanbe
reproductive rate, the Seychelles Magpie Robin lays protected against predators. It is hoped that habitat
onlya single eggat each nestingattempt, in anenvi- restoration through the planting ofnative woodland
ronment where the population already appeared to and suppression of invasive exotic vegetation will
beatcarryingcapacitywouldnotbeeasy.Atwo-year eventuallyraisenaturalfoodavailabilitytoalevelthat
research programmewas initiated in 1988 to investi- willallowsupplementaryfeedingtobediscontinued.
gate the biology of the Magpie Robin and identify A further long-term aim is to reduce the species vul-
possible ways ofcounteracting the threats to its sur- nerabilitybyre-establishingbreedingpopulationson
vival5.Onthebasisoftheinformationgatheredduring otherislands within Seychelles.
thisstudyBirdLifeInternational(thenICBP)launched
a recovery programme in 1990 to tackle the major Management Techniques and Results
threatsoflow productivity, relatively high adult mor- Sincethebeginningoftherecoveryprogrammenest-
talityandthelimitedextentandgenerallypoorquality ingMagpieRobinsandthoseinthepoorestterritories
havebeensupportedbyprovisionofadditionalfood.
In late 1992, however, a programme ofdaily feeding
inallterritorieswasbegun.Thebirdsaregivenfreshly
killed cockroaches equivalent to approximately 20%
of their daily food requirement. This is sufficient to
promote more frequent nesting and improve chick
survival butdoesnotsignificantlydisruptnaturalfor-
agingbehaviour. Duringtheperiodofsupplementary
feeding pairs have produced, on average, morethan
three eggs per year compared to 1.7 eggs per year
previously.Nestlingmortalityhasalsofallenfrom40%
to9-6%.
Inordertocounteracttheshortageofnaturaltree-
holesandprovidemoresecurealternativestothenest
sites available a total of 63 nestboxes have been
erected to date. These are readily used by Magpie
JuvenileSeychellesMagpieRabinCopsychusseychellarum, Robins. Fittingbroad polythenestripsabove and be-
CousinIsland,October1995(NeilMcCulloch)
82 BullABC Vol3 No2 Seychelles Magpie Robin: McCulloch
lowboxeswilldetermostclimbingreptiles.Boxesare onneighbouringCousineanditislikelythatprospec-
now used for approximately 50% of all nesting at- tive mates will be moved from Fregate soon.
tempts. The fledging rate from eggs laid in boxes is Transfers toAride have, unfortunately, been less
10%higherthaninothersitesbut, moresignificantly, successfuldespiteitsvegetationalsimilaritytoCousin
only 17% of nests in boxes are abandoned before and its recordofhavingheld a natural population of
laying while 31% ofnests begun in coconut crowns MagpieRobinsintothiscentury.Ninebirdshavebeen
never reach the egg stage because of disturbance. moved to Aride since 1992 but only two currently
Nest predation by Indian Mynas continues to be a survive there. Both disease and predation, probably
problemandmeasuresare regularlytakento control byintroducedBarnOwls Tytoalba havecontributed
,
numbers ofthis abundant introduced species which to losses. Aride appears to present a more complex
alsocompeteswithMagpieRobinsfornestsitesand, situation to that on Cousin. Research and habitat
tosome extent, forfood. improvementarecontinuingandthelessonsfromthe
There is strong circumstantial evidence that the pastsetbacksarebeingassessed inanefforttorefine
high adultmortality foundamong Magpie Robins on procedures for future transfers to the island. Despite
Fregate intheearlyyearsoftherecoveryprogramme the problems eggs have recently been laid on Aride
mayhavebeenatleastpartlyattributabletothebirds andhopesarehighforsuccessfulbreedinginthenear
eatinginsectskilledbyhouseholdpesticidesandsim- future.
ply swept out of dwellings. In 1991 agreement was
reachedwith the islandmanagementthat insecticide
sprayswould no longerbe made generallyavailable
on Fregate. Birdlife International subsequently initi-
ated trials with safe, hormone-based, insecticides
whichweresuppliedtoislandresidentsfreeofcharge’.
Since the implementation of the pesticide ban the
annual adult mortality rate of Magpie Robins has
dropped from an average of20%to 3% in 1995. The
reducedmortalityandincreasedproductivityachieved
bytheimplementationofconservationmeasureshad
resulted in the growth of the world population of
SeychellesMagpieRobinsto60individualsbytheend
of 1995, an increase of 173% since the start of the SeychellesMagpieRobinbeingloadedontoahelicopterfor
project. transporttoCousinIsland,November1994(AdrianSkerrett)
Fromthe startofthe recoveryprogramme efforts
have been made to clear substantial areas ofdense, Rat Threat
scrubbyundergrowthfromthewoodlandon Fregate Despitetheincreaseinnumbersbroughtaboutbythe
using local labour. Where possible areas are being recovery programme, the vulnerability of the Sey-
replanted with indigenous trees. More than 4,000 chelles Magpie Robin was again emphasised in
treeshavebeenplantedtodatebutthiswilltakesome September 1995 when itwas discoveredthat Fregate
time to bring significant benefit to the Magpie Robin Island had been invaded by Brown Rats Rattus
population. norvegicus. These appear to have gained access via
boatcargofortheplantationandtheirarrivalisamajor
Translocations
setback for the project. Unless the rats can be eradi-
The recent increase in Magpie Robin numbers on cated quickly there is a dangerthat as theirnumbers
Fregateandtheshortageofsuitablehabitatthere has increasetheywillturntonestpredation.Egglossfrom
allowedtheexperimentaltranslocationtothreesmall othercausesisalreadyhighandfurtherpressurefrom
islands free of mammal predators (Cousin, Cousine rats would seriously endanger the Magpie Robins
andAride). ResultsfromCousinhavebeenextremely recovery. It is probable that incubating females and
encouraging. Thetwo pairs introduced inNovember newlyfledged juvenileswouldalsobe at risk. A poi-
1994havesinceproducedsixoffspring,allsurviving, soningandtrappingprogrammeisalreadyunderway
and a more recently transferred pair has also begun but,whilethisappearstobeexertingsomecontrolon
nesting. Supplementaryfeedinghasprovedunneces- theratpopulation,totaleradicationisunlikelyunless
saryinCousin’spredominantlynativewoodland.Two substantial additional funding can be obtained. The
maleMagpie Robinshaveadaptedwelltoconditions dangersofsecondarypoisoningofbirdsduringafull-
Seychelles Magpie Robin: McCulloch BullABC Vol3 No 2-83
scale eradication campaign present serious logistical sion to transferMagpie Robins to Aride and Cousine
problems, however, and would make it necessary to respectively. The author thanks Rob Lucking, Vicki
remove a substantial numberofMagpie Robins from Ayrton, Stella Le Maitre, Lisa Shorey, GeoffMorgan,
the island ortake them temporarily into captivity. Andy Bunton, Jim Glover, Chris Skinner, James
Wolstencroft, DebbieLochhead, KristofferSorensen,
The Future Robbie Bresson and the Cousin staff for their dedi-
The Seychelles Magpie Robin population is now in a catedassistanceinthefield.MikeRands,DonMerton,
healthier state than it has been for several decades. Nirmal Jivan Shah, Adam Gretton, Jan Komdeur,
NumbersonFregatearethehighestrecordedandthe Victorin Laboudallon, Jeff Watson, Jim Stevenson,
speciesisnowbreedingagainonotherislands.How- John CollieandJudyJackson all providedinvaluable
ever, the success ofthe last five years has yet to be advice and support. ®
consolidated.Problemsremain.Itisuncertainwhether
the rat threat on Fregate can be fully controlled. Nor References
canityetbeassessedquitehownewtourismdevelop- 1. Collar, N.J., Crosby, M.J. and Stattersfield, A.J.
ments on Fregate will affect the birds. Landscaping 1994. Birdsto Watch2: theworldlistofthreatened
associated with a new hotel on the island has the birds. Cambridge: BirdLife International.
potentialtomakeasignificantcontributiontohabitat 2. Collar, N.J. and Stuart, S.N. 1985. ThreatenedBirds
rtehsetoprlaatniorneimfacianrsrieudncoluetars.ymTphaetheptoitceantlilayl,bfourtmreu-icnhtroo-f DofatAafrBiocoak,anPdartre1l.atCeadmbisrliadndgse-,: Itnhteer1nCaBtPio/n1aUlCCNoRuen-d
cil for Bird Preservation.
ductions ofMagpie Robins to other islands has been 3. Crook,J.H. I960. The present status ofcertain rare
demonstrated but suitable predator-free islands are land birds of the Seychelles Islands. Seychelles
few and some may be too small to support self- Government Bulletin.
sustaining populations. More resources are urgently 4. Edwards, J.P. 1992. Report on the use of environ-
needed for the removal of introduced species from mentally compatible insect control agents in the
islands which could provide refuges for native wild- conservation of the Seychelles Magpie Robin. In-
life.Thetechniquesandexpertiseneededtosavethe ternal report: ICBP.
Seychelles Magpie Robin already exist. What is most 5. Komdeur, J. 1988-1990. The Seychelles Magpie
Robin Copsychussechellarum: Progress Reports 1-
needed, however, is commitment and long-term vi-
13. Internal reports: ICBP.
sionfromallthoseinvolvedintheconservationofthis 6. LangrancI, O. 1990. GuidetotheBirdsofMadagas-
fascinating component of a unique avifauna. Much car. New Haven and London: Yale University
remainsto be done but the outlook isoptimistic and Press.
the project has demonstrated the potential of inten- 7. McCulloch, N. 1994. Rescuing the Seychelles Mag-
sivemanagementofwildpopulationsasaninitialtool pie Robin. RSPB Conservation Review 8: 88-94.
intheconservationofcriticallyendangeredrestricted- 8. Penny, M. 1968. Endemic birds of the Seychelles.
range species. Oryx 9: 267-275.
9. Rands, M.R.W. and Komdeur, J. 1989. Saving the
Acknowledgements Seychelles Magpie Robin Copsychus sechellarum:
TheSeychellesMagpieRobinRecoveryProgrammeis a recovery plan for one ofthe worlds most threat-
funded by the Royal Society for the Protection of ened birds. Internal report: ICBP.
Birds. BirdLife International is indebted to the Gov- 10. WV.at1s9o9n2,.J.T,hWearSmeyacnh,elSl.e,sToMdadg,piDe. aRnodbiLnabCooupdsaylclhonu,s
ernment ofSeychelles for its active collaboration in sechellarum: ecology and conservation of an en-
theproject.Theco-operationofDrO. Happel,owner dangered species. Biological Conservation 6l: 93-
ofFregate Island, and his staffis gratefully acknowl- 106
.
edged. Thanks are also due to the Royal Society for
NatureConservation and toMrF. Keeleyforpermis- BirdLife International, Wellbrook Court. Girton Road,
Cambridge, CB3 ONA, UK.
84 - BullABC Vol3 No2 Seychelles Magpie Robin: McCulloch