The conservation status of Echo Parakeet, Psittacula eques, of Mauritius

5 Pages·1998·3.9 MB·

by  Mike Thorsen

The conservation status of Echo Parakeet
Psittacula eques of Mauritius
MikeThorsenaandCarlJonef
Introduction and background
O
n human colonisation of Mauritius, three en-
demicspeciesofparrotwerenoted:Lophopsittacus
mauritiana a large, crested and heavybeaked grey
parrotthatbecameextinctaround1680,Lophopsittacus
bensoniasmallergreyparrotthatbecameextinctinthe
1760s, and the still extant Echo Parakeet Psittacula
equesl
.
The Echo Parakeet is a medium-sized parakeet
weighing 130-190 g. It is similarin size to the intro-
duced Ring-necked ParakeetPsittaculakrameribut
is heavier, more solid in appearance and the tail is
almostequalinlengthtothebody.EchoParakeetsare
alsoadarkergreencolour, havelowerpitchedcalls,
slower flight, and females have a dark beak. It has
beentreatedasasubspeciesofRing-neckedParakeet
but was considered specifically distinct by Jones4
.
Thisseparationappearstobevalidbasedonecologi-
cal observations and breeding biology. An
investigationintothe evolutionarydivergence ofthe
Indian Ocean Psittacula species is underway (J
Groombridge pers. comm.). Juvenile Echo ParakeetPsittacula eques, Mauritius,January
EchoParakeetsareherbivorous,eatingfruit,flow- 1997(RobertLucking)
ers,leaves,budsandbarkofawiderangeofspecies.
Theyforagewidelyandtargetdifferentplantspeciesat hatchingandgrowquickly, peakingataround 170g
certaintimesoftheyear5. beforefledgingatcl50g,53-63daysaftertheyhatch.
Nests are in cavities ofemergent endemic trees. Twoyoungisthemaximumnumberknowntofledge
Theclutchsizeisnormally2-3eggs(range1-4)which fromanest.
are laidfrom September-December. Eggs are laidat EchoParakeetswereformerlycommononMau-
two-day intervals. Incubation starts with the first, or ritiusbutbegantodeclineinnumbersandrangeinthe
sometimes second, egg and lasts 21-25 days. Only mid-1800s, until by 1986 the population was esti-
femalesincubate.Chicksweighbetween8.5-11gupon matedatonly8-12 individuals5,6. Theyarenowonly
found in c50 km2 of remnant native upland forest6
.
Thisareaiscontainedwithinthe7,000haBlackRiver
GorgesNationalParkcreatedin 1993- NoEchoPara-
keetsarepresentinanyotherareaofMauritius.
Only 1.27% ofMauritius’ native forest remains3
.
Thisforest,whichtheEchoParakeetinhabits,contin-
uestobehighlydegradedbycyclones, theinfluence
ofpastforestrypracticesandbythe spreadofexotic
plants especiallyGuavaPsidiumcattleianum, Privet
Ligustrum robustum and Jamrosa Syzygium
jambos1’2'5’6. Many alien feral mammals are present
including Ship Rat Rattus rattus and Norway Rat
Rattus norvegicus, Macaque Monkeys Macaca
BlackRiverGorgesNationalPark,Mauritius,January1997
(RobertLucking)
122-BullABC Vo!5No2 ConservationstatusofEchoParakeetofMauritius: Thorsen&Jones
Population growth
ThetotalEchoParakeetpopulationhasgrownquickly
overthepastthreebreedingseasons.Amajorreason
forthis is the intensivemanagementprogramme.
The discoveryofnewbreedinggroups in recent
yearshasalsoraisedthepopulationtotal.Someofthese
were almost certainly present in previous years but
withoutintensivesearchingremainedundetected.
Achangeintheproportionofbreedinggroupsthat
attempttobreedeachyearhasalsoplayedaroleinthe
population increase. For the period 1973-1994 only
42-60%ofthe knownbreedinggroups attemptedto
breed.Overthelastthreebreedingseasonsthisfigure
has risen to 92%. The reason for the increase in
Fig.1.EchoParakeetPsittaculaequespopulationtrend5.wu2 breedingattemptsisunknown. Currentmanagement
techniquesdonotincludemethodsforincreasingthe
proportionofbreedinggroups.Anincreaseinavailable
fascicularis, domestic Cats Fells cattus, Mongooses food supply due to increasing utilisation of exotic
Herpestes auropunctatus, Pigs Sus scrofa and Rusa species may be the answer. Prior to the 1994-95
DeerCervustimorensis,whichhaveasignificantnega- breedingseasonexoticspeciescomprisedveryfewof
tCiovememffoecntoMnyinnadiAgcernioduosthfelorreasatnridstfiasuannad15R6.iInngt-rnoedcukceedd cfoenetdriansgtsowbistehrva2t6i%onisn (149%955,—936%11 iannd193931—%94in7).19T9h6is—
ParakeetarenestsitecompetitorswiththeEchoPara- 9712 Particularlyimportantcould,betheexceedingly
.
keet1. commonGuavawhichcanfruitveryheavilyinJuly-
ThedeclineoftheEchoParakeethasbeenattrib-
uted to habitat destruction and degradation, exotic
predators,competitionfornestcavities,seasonalfood Tsaubmlmear1.yWsiilndceEc19h7o35.P6,a8r,1a1k,1e2etPsittaculaequesbreeding
shortages,nestflyinfestationsandgenetic/demographic
reasons56. Year Number Number Number Number
ConservationeffortstorecovertheEchoParakeet of known of groups of groups ofyoung
wereinitiatedbytheMauritianWildlifeFoundationin breeding laying fledging fledged
1973 and intensified in 1987. Many techniques have groups eggs young
successfully
beenusedincludinghabitatprotectionandimprove-
ment (fenced and weeded forest plots), rat control 1973 _ 7(11) 2(7) 2-4 (11)
aroundnestsites,manipulationofnests,supplemen- 1974 -11 -7 6(4) 11 (5)
taryfeedingandprovisionofnestboxes6 1975 - 6(6) 1 (2) 2(4)
Between 1993-1993, theprogramme.wasfurther 11997767 -6-11 (-) --(-) -3(0) -5(0)
refinedandcurrenteffortsarebasedonthismethod- 1978 3 1 0 0
ology.Themainemphasisisnowonpredatorcontrol, 1979 3 0 0 0
nest cavity improvement, clutch manipulations and 1980 2 1 0 0
daily examination of active nests. As a result, Echo 11998812 21 01 00 00
Parakeetisoneofthemostintensivelymanagedavian 1983 1-2 0 0 0
speciesintheworld. 1987-88* 4 1 1 5
Sincethe 1994-95breedingseasontheminimum 1988-89 4 1 0 0
EchoParakeetpopulationhasbeenincreasingrapidly 1989-90* 4 2 2 5
1990-91* 4 3 2 5
(by 47% in 1994-95, 47% in 1995-96, and 68% in 1991-92* 4 3 3 7
1996-97).Attheendofthe 1996-97breedingseason 1992-93* 5 2 1 4
the total population was 84-95 individuals12. Forty 1993-94 5 3 0 0
chicks have now fledged fromwild eggs in the past 1994-95* 6 6 4 8
1995-96* 7 6 5 11
three breeding seasons. However, only 12 of these 1996-97* 13 12 10 21
have fledged into the wild. The following is a more
focusedexaminationofthecurrentthreatstotheEcho * Figures include wild eggs and nestlings harvested and
Parakeetand current conservation methodology. reared in captivity.
a second estimateforthe season.
( )
ConservationstatusofEchoParakeetofMauritius: Thorsen&Jones BullABC Vol5No2- 123
— —
September,whenbreedinginitiationprobablyoccurs heldbysomewildlifemanagers.Attemptscontinueto
in Echo Parakeets. A grove of introduced Starfruit introducewildadultstosupplementaryfoodbutwith
Averrhoa carambola trees is much-utilised by Echo little success to date. Released captive-reared juve-
Parakeets fromJanuary-March13 This use of exotic nilesaretrainedtousesupplementaryfoodprovided
. —
foodsourcesisapromisingsigninthatitcouldrelease in parrot feeders as used on the Kakapo project
EchoParakeetsfromoneoftheirmajorconstraints whichexclude otherbirdspecies andrats.
food shortage due to habitat deterioration.
Rejuvenation ofthe breeding population by recruit- Clutch manipulations and rescues
ment ofyoung birds could also have increased the Aspartofthemanagementprogramme,thefirstclutches
breeding proportion. ofselectedbreedinggroupsareharvestedtoincrease
productivityvia double clutching. Fostering ofeggs
andnestlingsisalsoutilisedtospreadrisksandcircum-
The role offood supplies ventparentingproblems.Rescuingofatriskclutches
Seasonalfoodshortageshaveoftenbeendiscussedas andstarvingnestlingsisverysuccessfulatmaintaining
one of the reasons for the Echo Parakeet’s rarity5,6. productivity.Thisisanessentialtechniqueinyearsof
Results from the past four breeding seasons suggest poorfoodavailabilityoradverseweather.Dailyinspec-
foodshortageasthemajorcauseofnestfailurewithin tionofnestlingsallowsproblemstobedetectedearly
themanagementprogramme.Duringsuccessfulbreed- andremedied.Harvestingeggsandrescuingclutches
ing seasons, eg 1994-95, most breeding groups, over the past three years has bolstered the captive
managed or not, can successfully fledge young, but population at the Gerald Durrell Endemic Wildlife
during‘normal’breedingseasonsmostnestsfailorare Sanctuary (GDEWS).
onlyabletofledgeareducednumberofyoung.
Thereasonforthisfoodshortageisdeterioration Management of nest cavities
ofthe native forest. All areas where Echo Parakeets Nestliningsconsistingofwood-shavingstreatedwith
nowbreedcontainonlypatchesofnativevegetationin afungicideandinsecticideareusedinallaccessiblenest
a sea of Guava and Privet. While these exotics can cavities.Thishasbeenveryeffectiveinthatnonestsare
provideaveryabundantfoodsourceitisnotavailable knowntohavefailedduetonest-flyorfungalinfesta-
year-roundoreventhroughoutthebreedingseason. tionsinthepastthreeseasons. Inthe1993-94season
Normalfruitinglevelsofnativespeciesarepatchyin nest-flypredationwasresponsibleforoneofthreenest
distribution and frequency with only some species failures. Aspergillosus infection has been noted as a
fruiting eachyear. This is demonstrated bythe little cause ofnestfailure at GDEWS inthe past8.
overlapinnativespeciesrecordedinfeedingobserva- ManyofthecavitiesusedbyEchoParakeetsare
tions from breeding season to breeding season. becomingoldandunusable. Theremaybe a lackof
Macaquesalsostripmuchofthefruitfromtrees,often alternative cavities due to the limited numbers of
beforeitripens. mature cavity bearing trees in the highly degraded
Cyclones can stimulate the native vegetation to forest. Competitionalsoexistsforcavities(seeCavity
fruitabundantlythe followingyear, which increases competition).Weatherproofingandcavitymaintenance
breedingsuccess areongoingactivities.
Supplementary feeding Cavity competition
Supplementaryfeedingcanbeveryusefulinremoving Competition for nest cavities appears high with 14-
food limitations onbreeding output. Mostconserva- 19%ofEchoParakeetnestcavitieslosttocompetitors
tion programmes with a supplementary feeding eachyear12 Themainculpritsare(inorderofimpor-
.
component report an increase in breeding attempts tance): Ring-necked Parakeet, Common Myna,
(eg Kakapo Strigops habroptilus10 Seychelles Mag- White-tailedTropicbirdPbaetbonlepturusandbees.
,
pie-Robin Copsychus sechellarum (R Lucking pers. Not included in the above figures are take-overs of
comm.) and of course the Mauritius Pink Pigeon cavities notactivelyinuse orbetweenbreedingsea-
NesoenasmayeriandMauritiusKestrelFalcopunctatus sons.Termitesandratshavebeenresponsibleforthe
(CJ pers. obs.). Supplementary feeding programmes former. Other potential nest competitors are wasps
havetobedesignedintelligentlyandmonitoredclosely andMauritiusKestrels.
toavoidproblemssuchasinfertility,femaleburn-out Cavitylossduetocyclonesandgeneraldeteriora-
and an increased disease risk, which are concerns tionduetoagealsotakesitstoll.Jones&Duffy6found
124-BullABC Vol5No2 ConservationstatusofEchoParakeetofMauritius: Thorsen&Jones
a lossof18%percavityyear. Cavitymaintenance as Known causes of mortality of nestlings include
partofthemanagementprogramme probablyslows ten instances of starvation, three instances each of
the rate of cavity loss due to deterioration as no disease, nest-fly parasitism, cavity take-over, deser-
cavitieshavebeenlostsincethe1993-94season.Two tion, and one instance each of drowning during a
cavities (3.4% per cavity year) are known to have cyclone andgrowth abnormality12
.
beenlostincyclonessince198768 Temple(inJones&
.
Duffy6) describes nine of 23 (38%) cavities being The role of surplus males
destroyedina cyclone in 1975. Most breeding groups have 1-3 ‘surplus’ males in
Cavity competition may not yet be a limiting attendance.Debatecontinuesastowhethertheseextra
factorfortheEchoParakeetpopulationasallknown malesare ‘helpers’ or‘hinderers’. Atthestartofnest-
breedinggroupsareinpossessionofacavity.Ifpres- ing,subdominantmalesareusuallychasedoffbythe
suretofindbreedingsitesexistedthensomeofthe57 dominantmaleorthefemale.Astheseasonprogresses
nestboxesinstalledsince1974shouldhavebeenused, andtheparentsareabsentforlongerperiodsoftime,
butnonehasyetbeenusedbythespecies(pers.obs.). someoftheextramalesenterthenestcavityandfeed
AstheEchoParakeetpopulationincreases, competi- thenestlings.Occasionallyextramalesarealsoknown
tionfornestsiteswillprobablyincrease. tofeedtheincubatingfemaleifthedominantmaleis
absent.Theseextrafeedingsprobablybenefitboththe
Rodent control femaleandthenestlings.Howeverwildfledgingsuc-
The large number of rats present in the Mauritian cessappearstobeindependentofgroupsizeandmay
forestswillbothpredateeggsandnestlingsandcom- infactbemorecloselyrelatedtothedominantmale’s
petewithEchoParakeetsforthelimitedfoodsupplies experience.
available. Current efforts to control rats around nest Some examples ofhindrance are documented.
sitescentreontwotechniques: a 200m2poisongrid Jones5 quotes an instancewhen a male replacedthe
centred on the nest site, or surrounding the cavity dominantmaleatanestwhichthenfailedaweekorso
entrancewithphysicallyinsurmountablePVCsheeting. later.Inthe1994-95season,twonewlyhatchednest-
Thelattertechniqueisstillbeingdevelopedandneeds lingswerefoundwiththeirheadscrushedeitherbyan
specialcaretobeeffective. extramaleorbyCommonMynas(whichwerenesting
1 mbelowthecavity)8.
Capture and banding Withonlytworecordedinstancesof’hindrance
Captureofadultbirdsinthenestcavityasatechnique thebalancestronglyfavourssurplusmalesbeingben-
has allowed the ringing ofadults as well as fledged eficialorneutral.
juveniles.Theringingprogrammehasbeeninvaluable Surplusmalesatnestsmaybearecentphenom-
in determining movements and breeding success of enonasitwasnotobservedbyFStaubinthe1960sor
individualsandnestsiteoccupation. intwonestsin1971,butitwasrecordedbySTemple
inthe 1974breedingseason5.Jones5theorisedthatit
Mortality and sex ratio of wild birds wasdueeithertotheskewedsexratiotowardsmalesor
Mortality of adult Echo Parakeets is very low. Only tonon-breedingbirdsdisplacedbyforestclearance.A
4.2% per annum ofbanded females and no banded skewedsexratioprobablyencouragesmalestojoina
maleshavedied,althoughthesefiguresoriginatefrom breedinggroupwheretheyhaveachanceofsecuring
averysmallsample12 Jones&Duffy6alsonotehigher eithercopulationsoramatebydisplacingthedominant
.
mortalityinfemales.Thisdifferentialmortalityifcar- male.Suchdisplacementwasobservedinthe1995-96
riedoverseveralyearscouldresultinthebiasoftwo seasonwhenthedominantmalefromabreedinggroup
malesforeveryfemaleinthepopulation. washeldincaptivityovernight.Beforeitwasreleased
Juvenilemortalityappearstobec20%perannum12 thenextdaytheothermalehadstartedattendingand
.
However, thishasagainbeencomputedfromavery feedingthe female. Once the male was releasedthe
small sample. There are no documented causes of normaldominancehierarchywasre-established11
.
mortalityofadultbirds.Jones5postulatesdirect(through Howthepresenceoftheextramalesistranslated
destructionofbirdsincavities)andindirect(starvation to helping behaviour such as feeding the nestling
duetoloweredfoodsupply)cyclone-relatedmortality. (feedingthefemalecouldbeexplainedasadisplaced
AmacaquehasbeenobservedcarryinganadultRing- courtship ritual) is unknown. Perhaps the males are
neckedParakeet(SRoypers.comm.). simplyrespondingtobeggingstimuliwhilehormone
levelsarehigh.
ConservationstatusofEchoParakeetofMauritius: Thorsen&Jones BullABC Vol5No2-125
Disease and inbreeding 7. Lovegrove,T.G.,Wadum,L.A.andNieuwland,A.B.
Diseasescreeningshowsthatdiseasesareeitherpreva- 1994.ManagementoftheEchoParakeet(Psittacula
lent throughout the population (Polyoma Virus and equesecho) ofMauritius, 1993-94 season. Unpub-
lishedreporttotheJerseyWildlifePreservationTrust
HerpesVirus)orareentirelyabsent(Psittacenebeak &MauritianWildlifeFund.
andfeatherdisease, bloodparasites) (AGreenwood
8. Lovegrove,T.G.,Nieuwland,A.andGreen,S. 1995.
pers. comm.). There is little evidence to date of in- ManagementoftheEchoParakeet(Psittaculaeques
breedingandfertilityis96%9, buttheoccurrenceofa echo)ofMauritius,1994-95season.Unpublishedre-
softboneconditioninsomenestlingscouldbedueto port to the Jersey Wildlife Preservation Trust &
inbreeding. MauritianWildlifeFund.
9. Murray,K.A. 1998.Thesupplementationofthewild
Releases of captive birds populationwithcaptive-bred,hand-rearedEchoPara-
Thefirstreleaseintothewildofthree captive-reared keets(Psittaculaeques)intonativeforestofMauritius:
Echo Parakeets successfully occurred inJuly 19979 afirstrelease.UnpublishedreporttoMauritianWild-
Most captive-reared individuals from eggs and nest-. lifeFoundation.
10. Powlesland, R.G. andLloyd, B.D. 1992. Useofsup-
lings removed from wild nests, supplemented by
plementaryfeedingtoinducebreedinginfree-living
captive-bredindividuals,willbereleased.Thesebirds Kakapo Strigopshabroptilus in New Zealand. Bio-
aretaughttousesupplementaryfeedingstationsand logicalConservation69: 97-105.
niendsitvbiodxueasls.tItoiussheoptheedsethbayttahsesyocwiialtlioinn.tu:'rpntrainwild 11. S1h9o9r6t.eMn,anR.a,gTehmoresnetn,ofM.wi,lGdreEecnh,oS.PaarnadkeBeutcsh.aInnanM,anG-.
agementoftheEchoParakeet{Psittaculaeques)of
References Mauritius, 1995-96 season. Unpublished report to
1. Cheke, A.S. 1987. An ecological history of the JerseyWildlifePreservationTrust,MauritianWildlife
Mascarene Islands, with particular reference to Fund &World ParrotTrust.
extinctionsandintroductionsoflandvertebrates.In 12. Thorsen,M.,Shorten,R.,Buchanan,G.,Williams,S.
Diamond, A.W. (ed) Studies ofMascarene island andJones,V.1997.Thewildpopulation.InTheEcho
birds. Cambridge, UK: CambridgeUniversityPress. Parakeet{Psittaculaeques)ManagementReport,1997.
2. Cheke, A.S. 1987. The ecologyofthe smallerland- Unpublished report to World Parrot Trust, Jersey
birdsofMauritius.InDiamond,A.W.(ed)Studiesof WildlifePreservationTmst&MauritianWildlifeFoun-
Mascareneislandbirds.Cambridge,UK:Cambridge dation.
UniversityPress. 13. Wadum, L.A., 1995. Habitat use, breeding biology
3. Duffy,K.1994.Reproductivebehaviourandbiology and management of the Echo Parakeet Psittacula
oftheEchoParakeetCPsittaculaeques).Unpublished equesecho.Unpublishedthesis.Denmark:Roskilde
MScthesis. Canterbury: UniversityofKent. University.
4. Jones, C.G. 1980. Parrot on the way to extinction. a159B Ocean ViewRd, MtMaunganui, NewZealand*.
Oryx 13: 350-354. hJersey WildlifePreservation Trust, BlackRiver, Mauri-
5. Jones,G.C. 1987.Thelargerland-birdsofMauritius.
InDiamond,A.W. (ed)StudiesofMascareneisland tius.
birds. Cambridge, UK: CambridgeUniversityPress. *correspondingauthor
6. Jones, G.C. andDuffy, K. 1993. Conservationman-
agementoftheEchoParakeetPsittaculaequesecho.
Dodo29: 126-148.
126-BullABC Vol5No2 ConservationstatusofEchoParakeetofMauritius: Thorsen&Jones