Diel pattern of activity ofLestes macrostigmaat a breeding site (Odonata: Lestidae)

2011·0.32 MB·

by  Philippe H. Lambret

InternationalJournalofOdonatology
Vol.14,No.2,June2011,175–191
Diel pattern of activity of Lestes macrostigma at a breeding site
(Odonata: Lestidae)
PhilippeH.Lambret*andAnthonyStoquert
MaraisduVigueirat,F-13104Mas-Thibert,France
(Received1March2011;finalversionreceived25May2011)
Monitoringmethodsalwaysrecommendgatheringdataduringthemaximalactivityofadults.Hencemon-
itoringthethreatenedLestesmacrostigmarequiresknowledgeofitsactivitypattern.Dragonfly“activity”
isambiguousanditsintensitycanbeassessedindifferentways,includingbythethresholdofresponse
toapredatorstimulus,i.e.“awareness”.WestudiedthedailypatternofactivityofL.macrostigmaat
thebreedingsitebymonitoringthefrequenciesofbehaviours,especiallythoseofdifferentflights,flight
durationandspeed,andawareness.Wealsoassessedtheabundancetogetherwiththeprobabilitytodetect
thespecies.Thepatternofbehaviourwascharacterizedbyreproductionbutalsofeedingandroosting.
Flightactivitywasmoreintenseinearlymorningformales,aroundmiddayforpairs,andintheevening
formalesandfemales.Flightspeedwashighestaroundmidday.Thesepatternswererelatedtoambient
temperaturesandtoatrade-offbetweentheneedstomateandtofeed.Awarenesswasalmostconstantall
daylong,suggestingnewinsightsondailyactivityvariationsintheOdonata,especiallywhenperching.
Slightdifferencesbetweenmalesandfemalesindicatedoppositetrends.Thepatternofabundancewas
singularlytrimodal.Thisabundancedependsonthetruepresenceatthebreedingsiteandtoaprobabilityof
detection.Thetimingofmonitoringisthereforenottoberelatedtotheactivityperse,buttotheabundance
ofadults.WerecommendgatheringdataonL.macrostigmaduringearlymorning.
Keywords: Lestesmacrostigma;Odonata;activity;dielpattern;flight;reproductivebehaviour;postural
adaptation;detectionprobability;survey;monitoring
Introduction
Lestes macrostigma (Eversmann, 1836) is a threatened stenotopic species (see Lambret, 2010;
Lambret, Cohez & Janczak, 2009) inhabiting a disappearing ecosystem in the Mediterranean
(Zacharias&Zamparas,2010).Lambret(2010)underlinedthat,acrossitsrange,twoofthemajor
conservationactionsforthisspeciesaretoimproveknowledgeofitsdistribution–usingsurveys–
andtoassesswhetherpopulationtrendsareincreasingordecreasing–usingmonitoringbasedon
thetransectmethod(e.g.Pollard&Yates,1993)ortheoccupancymethod(McKenzieetal.,2002).
Withinentomologicalsurveyandmonitoring(ESM)itisusuallyrequiredtocollectdatawithin
thepeak(s)ofactivityoftheconsideredtaxon(Odonata:Ketelaar&Plate,2001;Smallshire&
Beynon2010;Rhopalocera:Manil&Henry2007)andwhenESMfocusesonasinglespecies,the
*Correspondingauthor.Email:[email protected]
ISSN1388-7890print/ISSN2159-6719online
©2011WorldwideDragonflyAssociation
DOI:10.1080/13887890.2011.592134
http://www.informaworld.com
176 P.H.LambretandA.Stoquert
dailytimespanisrestrictedbyspecificactivitypattern(Thompson,Purse&Rouquette,2003).
Identifyingapeakofactivityimpliesthatonecanmeasureitsintensity.
Howeverwhatexactlyconstitutes“activity”isnotalwaysclearlydefinedwithinESMmethods
(Bouwman,Groenendijk,Termaat&Plate,2009;Brooks,1993;Dolný,2005;Ketelaar&Plate,
2001;Pont,Faton&Pissavin,1999;Smallshire&Beynon,2010;Thompson,Purse&Rouquette,
2003). According to odonatological studies, activity can be understood in different manners.
Firstitiswhatdragonfliesaredoing(e.g.perching,fighting,mating,foraging,movingfromone
habitattoanother,dispersing),andthefrequencyordurationofeachactivitytypecanbestudied
(Higashi,Nomakuchi,Maeda&Yasuda,1979;Norma-Rashid,1999;Rehfeldt,1989;Watanabe,
Matsuoka, Susa & Taguchi, 2005). Second, it can reflect flight frequency or duration (Hilfert-
Rüppell,1998;Norma-Rashid,1999;Watanabe&Matsunami,1990).Activityisimplicitlyrelated
to flight behaviour (Corbet, 2004). Recently, Corbet and May (2008) emphasized that perchers
(seeCorbet,1962),forinstancewhenfeeding,canperchandbeactive,whichimpliesthatonly
usingflightstoassessactivitymaybeinappropriate.Theysuggestedthatanalterationofresponse
to a predator disturbance defines whether an individual is inactive. A third way to approach
activityintensityisthereforetoassessthethresholdofresponse–whichonecancall“awareness”
–using,forinstance,thedistanceatwhichadragonflyisdisturbed.Toourknowledge,thishas
neverbeenusedbefore.Fourth,activitycouldbeassessedusingflightspeed:atemperatezone
Zygopteranflyingfasterinthemiddleofthedaycertainlyappearsmoreactivethanwhenflying
slowlyinthemorning.Fifth,activityiscommonlyrelatedtothenumberofindividualspresentat
thebreedingsite(Bick,Bick&Hornuff,1976;Conrad&Pritchard,1988;DeMarco&Resende,
2002; Gorb, 1992, pers. comm; May, 1980; Rehfeldt, 2003; Robinson & Frye, 1986; Testard,
1975;Utzeri,Falchetti&Carchini,1983).Corbet(2004)highlightedthatstudyingOdonataonly
at water can provide a misleading idea of their activity pattern. This fifth measure of activity
focusesonreproductivebehaviourbutclearlymakessensebecauseESM’sareusuallycarriedout
atthebreedingsite,whereoviposition,larvalgrowthandemergencesoccur,andthereforewhere
theautochthonyofpopulationscanbeexplored.
Recentstudiesemphasizetheneedtotakeintoaccounttheprobabilityofdetectingaspeciesin
ordertoestablishrealistictrendsovertheyearsorcomparisonsbetweensites(Bonifait,Defosdu
Rau&Soulet,2008;Kéryetal.,2010;vanStrien,Termaat,Groenendijkb,Mensingb&Kéryc,
2010).Odonateactivitydependsonambienttemperature,T (e.g.DeMarco&Resende,2002;
a
Hilfert-Rüppell,1998;May,1980;McKay&Herman,2008;Pilon,Pilon&Caron,1995;Sformo
& Doak, 2006) and during the day, lestids adapt to T and regulate their body temperature T
a b
by behavioural and postural adaptations (McKay & Herman, 2008; Robert, 1958;Watanabe &
Tagushi,1993).Weexpectthoseadaptationstohaveanimpactonthedetectabilityofthespecies.
The aim of this study was to assess throughout the day, at the breeding site, the following
parameters: (i) the nature and frequency of L. macrostigma activities and their related flight
intensity;(ii)theintensityofactivityintermsofflightspeedandawareness;(iii)presence;and
(iv) exposure to the sun and height of perch, i.e. postural adaptations. We thereby wanted to
identifythemostfavourabletimeofdayforalong-termESMofL.macrostigma.
Materialsandmethods
Studysites,timingandweatherconditions
The study took place in two protected areas of the Camargue, Southern France: the Marais du
VigueiratandtheTourduValat.TheformerbelongstotheConservatoiredulittoral,i.e.theFrench
coast conservatory, a public establishment. The area is centred on coordinates 43◦32(cid:3)10(cid:3)(cid:3)N /
04◦45(cid:3)15(cid:3)(cid:3)E and covers 1200ha, consisting mainly of marshes. One of these, the Baisse des
DielpatternofactivityofLestesmacrostigma 177
Marcels,isaplotsurroundedbydams.Thesurfaceofitssouthernpartisc.1.5haanditsbottom
ismoreorlessflat,varyingbetween15and28cmasl(median=24cmasl,n=35).Thewater
managementconsistsintheinflowoffreshwaterfromthecanaloftheVigueiratfromc.October
toApril(valvesofditchesbetweenthecanalandtheplotareopen)andevaporationtherestof
the year (valves are closed) because of the hot temperature and strong wind of the Camargue
(Picon,1980).Thismanagementresultsinatemporarybrackishswamp;duringthestudyperiod,
thewaterdepthvariedbetween25and0cm(drysoil).DozensofLestesmacrostigmahavebeen
seen in the southern part of the Baisse des Marcels every year since 2005. Other encountered
ZygopteraareL.sponsaHansemann,SympecmafuscaVanderLinden,IschnuraelegansVander
LindenandI.pumilioCharpentier.Thevegetationisgrazedfromspringtoautumnandincludes
Bolboschoenusmaritimus(L.)Palla,JuncusmaritimusLam.andJ.subulatusForssk,aswellas
Schoenoplectus tabernaemontani (C.C.Gmel) Palla, Eleocharis palustris (L.) Roem. & Schult.
andPhragmitesaustralis(Cav.)Steud.;bordersarecolonizedbyTamarixgallicaL.,J.acutusL.
andArthrocnemumspp.
Thesecondisanareacovering2560ha,ofwhich1845hahasRegionalNaturalReservestatus.
Located5kmwestoftheMaraisduVigueirat(43◦30(cid:3)30(cid:3)(cid:3)N/04◦40(cid:3)00(cid:3)(cid:3)E),bothsitesareseparated
bytheriverRhône.Overthecenturiesthisriverhasshapedtheareaintoasetoftemporarybrackish
pondsandmarshesofdifferentsizes.L.macrostigmaisoneofthemostabundantOdonataand
breeds in at least 30 sites in the Tour duValat. One of them, the Relongues, covers more than
20ha and its water level depends on rainfall. Other Zygoptera are the same as above but L.
barbarus (Fabricius) is also present. The vegetation is grazed during winter and consists of B.
maritimus,P.australis,S.litoralis(Schrad.)Pallaand,onthebanks,J.maritimus,T.gallicaand
Arthrocnemumspp.
Dataweregatheredbetween9and30June2009andbetween6Juneand21July2010,when
populations were mature (Lambret, 2010), as it is known that sexual maturity of an individual
affects its activity (Mayhew, 1994).Activity may also depend on the age of individuals (May,
1980)butsinceitwasnotpossibletoassesstheageofstudiedanimalsandsincetheemergence
periodlastedin2010from7to30May(Lambret,unpubl.),ourdatasetreflectsamixtureofage
classes.
IntheCamargueduringthestudyperiod,solarnoonwasatc.13:45hlegaltime.Insummerin
France legal time equals solar time plus 2hours. Hereafter times are given as legal time minus
2hours. During the study period, the earliest and latest sunrises were at 03:59h and 04:02h
respectively;theearliestandlatestsunsetswereat19:19hand19:27h,respectively.Wetherefore
assumedthatthedifferenceofdurationbetweentheshortestandthelongestday–8min–was
negligibleregardingactivity.Timeofdaywasdividedinto1-hintervalsfrom04:00hto19:00h.
Duringeachalternateinterval,centredon04:30h,06:30h,08:30h,etc.,werecordedinformation
onbehaviourandnumbersofindividualsandpairspresent(seeAssessments,below).
MeteorologicalconditionsaffectOdonataactivity(Joseph&Lahiri,1989;Pilonetal.,1995;
Robinson&Frye,1986).Thus,dayswithrainand/orwithcloudcoverageover25%wereavoided.
Zygopteracanflyintoawindupto3.5ms−1(Hilfert,1994inCorbet,2004,p.312)butthestudy
sitewasshelteredbyTamarixtrees,resultinginawindspeedthatwasloweratthelevelofthe
groundthanatthelevelofthetrees,aconditionwhichallowsflightactivityduringwindydays
(Hilfert-Rüppell, 1998; Pilon et al., 1995).Thus, data were gathered with a wind force up to 3
Beaufort(5.5ms−1).
Assessments
ThreecategoriesofL.macrostigmawererecognized:males,femalesandpairs,hereafternoted
(cid:2),(cid:3)andP,respectively.Westudiedinall636animalsorpairs(Table1).
178 P.H.LambretandA.Stoquert
Table 1. BehavioursofLestesmacrostigmathroughouttheday:frequencies(%)ofeachbehaviourdisplayedwithin
5minutes.Cru&Patr=cruisingandpatrollingflights,Disp&Dist=wingthreatdisplayanddisturbancebyacon-
specific,SpTr&Cop=spermtransferorcopulation.Forpairs,onlyfemalegroomingisshownastheywerealways
thememberofthepairwhichdisplayedthisbehaviour,exceptasingleinstancewhenthemaledidalso(n=25).
Category Behaviour 04:30 06:30 08:30 10:30 12:30 14:30 16:30 18:30h
♂ Groom 20.69 60.00 26.67 9.68 18.75 20.00 3.33 23.33
Cru&Patr 72.41 86.67 82.76 45.16 61.29 46.67 60.00 66.67
Encounter 31.03 36.67 36.67 54.84 25.00 16.67 0.00 20.00
Disp&Dist 6.90 0.00 3.33 0.00 6.25 0.00 0.00 6.67
Feed 3.45 36.67 30.00 61.29 62.50 50.00 63.33 83.33
n 29 30 30 31 32 30 30 30
♀ Groom 13.33 13.33 35.48 29.03 5.88 20.69 23.33 10.00
Cru&Patr 10.00 23.33 35.48 77.42 23.53 41.38 30.00 66.67
Encounter 3.33 0.00 3.23 12.90 11.76 3.45 0.00 13.33
Disp&Dist 0.00 3.33 6.45 6.45 2.94 0.00 0.00 0.00
Feed 0.00 16.67 48.39 58.06 58.82 62.07 76.67 76.67
n 30 30 31 31 34 29 30 30
P Groom♀ 10.34 20.59 4.44 13.33 22.22
Cru&Patr 13.79 29.41 42.22 65.52 100
Encounter 3.45 5.88 4.44 6.67 44.44
Disp&Dist 27.59 17.65 20.00 20.00 11.11
Feed 0.00 2.94 2.22 6.67 22.22
Reproduction
Wait 100 100 93.33 26.67 33.33 0.00
SpTr&Cop 0.00 0.00 4.44 53.33 0.00 0.00
Oviposit 0.00 0.00 2.22 20.00 66.67 100
n 29 34 45 30 9 2
Animalswerefoundbywalkingandsearchingamongthevegetationwheretheyusuallyperch.
At first sight, we noted whether or not the animal was exposed to the sun and we assessed the
heightatwhichitperchedfromthewatersurfaceorthesoil.Itwasthenobservedwithbinoculars
for 5min. If our approach had disturbed the animal, we waited 2min before starting the 5min
observation.Eachbehaviourwasrecordedonafielddataformfixedtotheforearm,thusallowing
theobserveralsotooperateachronometer.Wesortedflightbehavioursascruisingandpatrolling
(sensuWatanabe&Matsunami,1990),feeding,andencounteringasinglezygopteranorapair,
disregarding for this last type of flight whether or not the focal animal returned to its original
perch.Iftheanimalencounteredanotherinthecourseofcruising,thebehaviourwasrecordedas
cruising.Thedurationofeachflightwasrecorded,andforeachinstanceofcruising,thedistance
between departure and arrival was estimated. Flight speed was calculated by dividing cruising
flightdistancebyitsduration.Disturbancewasestablishedwhenthefocalanimal,oroneorboth
membersofthefocalpair,displayedthewingthreatorleftitsperch,apparentlyduetoharassment
(e.g.Joseph&Lahiri,1989;Lutz&Pittman,1968;McMillan&Arnold,2003;Robinson&Frye,
1986);insomecaseswewerenotabletoseeifadisturbedanimaldisplayedthewingthreatbefore
flyingaway.Thedurationofeachinstanceofgroomingwasalsorecorded.Forpairs,wenoted
spermtransfer,copulationandoviposition.Attheendofthe5min,wewalkedseveralstepsfurther
fromthestudiedanimalbeforewestartedtosearchforthenextinordertoreducethebiasassociated
withobservingthesameanimalmultipletimes,i.e.toavoidpseudo-replication(Hurlbert,1984).
Awarenesswasstudiedbyfindingaperchedanimalwithbinocularsasdescribedabove.When
an animal was localized, we walked toward it until it escaped by flight, and we measured the
“disturbingdistance”,i.e.fromitsinitialpositiontous,usingarollingmetalruler.
Abundance at the breeding site was assessed by walking a transect across the southern part
of the Baisse des Marcels plot. This transect was 100m long and divided into two subsequent
segmentsof50m.Ateachsightingofananimal,werecordedifitwasaloneorpaired,inorder
DielpatternofactivityofLestesmacrostigma 179
to calculate the ratio of individuals in pair to the total number of individuals; we also assessed
itsdistancefromusinordertoassessthedetectability,i.e.theprobabilityofdetection,assuming
thatthefurtherwewereabletodetectananimal,thehigherthedetectability.
Air temperature and solar radiation were recorded by a Davis Vantage Pro meteorological
stationwhichissetintheMaraisduVigueirat.
Statisticalanalysis
Behaviouraldataweretreatedasbinary:animaldisplayatypeofbehaviour(seeabove)ornot.
Corresponding results are given as relative frequencies (sum =100%). Flight duration results
are given as median and sample size (n), considering all animals recorded at a given time of
day.Subsequently,wefocusedonanimalswhichflew,andwegivetherateofeachkindofflight
relativetothesumofflightdurationofallanimalsofthesamecategory.Becauseabundanceatthe
breedingsitewasstudiedoverseveraldaysandthemaximumnumberofindividualswasnotthe
sameoneachday,dataaregivenasfrequenciesrelativetothedailymaximum(sum =100%).
Significanceofcontingencytableswastestedusingχ2orG-tests.Thenormalityofdatasetswas
testedwiththeKolmogorov–Smirnovtest.InthecaseofaGaussiandistribution,weusedone-
wayANOVA; otherwise, we used the Kruskal–Wallis non-parametric test.Tukey’s and Dunn’s
multiplecomparisonposthoctests(MCTs),wereperformedinordertodeterminewhichclasses,
i.e. categories or times of the day, were responsible for significance in one-way ANOVA and
Kruskal–Wallistests,respectively.CorrelationsweretestedwithSpearmanranktests.Weexpected
aquadraticpatternofposturaladaptations;wethereforeusedageneralizedlinearmodeltostudy
the effect of time of the day t (in minutes) and its squared value t2, the category of animal C,
andtheinteractiontConexposuretosolarradiationE andtheheightatwhichanimalsperched
H.Theequationofthemodelisgivenwiththevaluesoftheestimatesandtheirstandarderror
betweenbrackets.
Statistical tests were performed with GraphPad Prism software but the GLM tests
with Statistica software and G-tests with an Excel spreadsheet available from http://udel.
edu/∼mcdonald/statgtestind.html(accessed16January2011).
Results
Flightdurationandbehaviourfrequencies
Grooming
Changesingroomingfrequencythroughoutthedayweresignificantlydifferentbetweenmales
andfemales(Table1;G-test:G=21.60,df =7,p <0.0001).Thepeakofgroomingfrequencies
occurredat06:30hformalesand08:30hforfemalesand,atthosetimes,thedurationdevoted
to this behaviour was significantly higher for males than at other times (Kruskal–Wallis test:
H =37.23,df =7,p <0.0001;Dunn’sMCT:06:30hversus10:30h:differenceinranksum =
65.12, p <0.01; 06:30h versus 16:30h: difference in rank sum =72.00, p <0.01), but not
significantlyhigherforfemales(one-wayANOVA:F =1.198,df =7,df =237,p =0.2519).
1 2
Peakgroomingfrequencyformaleswasalmosttwicethepeakforfemales.
Reproduction
Thefrequencyofpairsvariedsignificantlythroughouttheday(Kruskal–Wallistest:H =48.23,
df =7,p <0.0001).Itrapidlyincreasedfrom04:30htoreachthehighestfrequenciesbetween
180 P.H.LambretandA.Stoquert
Figure 1. FrequenciesofLestesmacrostigmapairsthroughouttheday:ratioofpairedindividualstothetotalnumber
ofindividualsatagiventimeoftheday.Inordertoincreasethenumberofreplicatesbothsectionsofthetransectwalks
werecountedseparatelyaswellaseachdatetocalculatethemedians(8≤n≤11,regardingtimeoftheday).
Table 2. Significant multiple comparison posthoc tests (MCTs): Dunn’s MCT for Kruskal–Wallis tests,
Drs=Differenceinranksum;Tukey’sMCTforone-wayANOVA:(a)proportionofpairedindividuals;(b)totalflight
duration;(c)feedingdurationper5minutes;(d)singlefeedingflightduration,excluding04:30hdatabecauseofsmall
samplesize;(e)abundanceatthebreedingsite;(f)detectability.
MCT Drs p MCT q p
(a) 06:30hvs14:30h 34.56 <0.05 (c) 04:30hvs16:30h 7.543 <0.001
06:30hvs16:30h 37.50 <0.01 06:30hvs16:30h 7.120 <0.001
06:30hvs18:30h 37.50 <0.01 08:30hvs16:30h 6.129 <0.001
08:30hvs14:30h 40.89 <0.01 10:30hvs16:30h 6.087 <0.001
08:30hvs16:30h 43.83 <0.001 12:30hvs16:30h 5.702 <0.01
08:30hvs18:30h 43.83 <0.001 14:30hvs16:30h 5.251 <0.01
10:30hvs16:30h 33.25 <0.05 04:30hvs18:30h 9.631 <0.001
10:30hvs18:30h 33.25 <0.05 06:30hvs18:30h 9.205 <0.001
(b) Category MCT Drs p 08:30hvs18:30h 8.243 <0.001
♂ 04:30hvs14:30h 60.29 <0.05 10:30hvs18:30h 8.210 <0.001
06:30hvs10:30h 66.00 <0.01 12:30hvs18:30h 7.861 <0.001
06:30hvs12:30h 73.54 <0.001 14:30hvs18:30h 7.368 <0.001
06:30hvs14:30h 108.6 <0.001 (d) MCT Drs p
06:30hvs16:30h 86.61 <0.001 08:30hvs12:30h 112.5 <0.05
08:30hvs14:30h 72.52 <0.001 10:30hvs18:30h −146.0 <0.001
14:30hvs18:30h −67.51 <0.01 12:30hvs16:30h −74.26 <0.05
♀ 04:30hvs10:30h −90.27 <0.001 12:30hvs18:30h −156.6 <0.001
04:30hvs12:30h −62.05 <0.05 14:30hvs18:30h −126.4 <0.001
04:30hvs14:30h −72.12 <0.01 16:30hvs18:30h −82.35 <0.001
04:30hvs16:30h −89.93 <0.001 (e) MCT Drs p
04:30hvs18:30h −130.4 <0.001 04:30hvs10:30h 46.25 <0.001
06:30hvs10:30h −70.05 <0.01 04:30hvs12:30h 35.50 <0.01
06:30hvs16:30h −69.72 <0.01 04:30hvs14:30h 43.94 <0.001
06:30hvs18:30h −110.1 <0.001 (f) MCT Drs p
08:30hvs18:30h −76.68 <0.001 04:30hvs08:30h 59.24 <0.05
12:30hvs18:30h −68.31 <0.01 04:30hvs12:30h 63.81 <0.05
14:30hvs18:30h −58.24 <0.05 04:30hvs14:30h 80.73 <0.05
P 04:30hvs10:30h −38.46 <0.01 04:30hvs16:30h 54.95 <0.05
04:30hvs12:30h −74.39 <0.001
06:30hvs08:30h 4.721 >0.05
06:30hvs10:30h −18.75 >0.05
06:30hvs12:30h −54.68 <0.01
08:30hvs10:30h −23.47 >0.05
08:30hvs12:30h −59.40 <0.01
DielpatternofactivityofLestesmacrostigma 181
Table 3. FlightactivityofLestesmacrostigmathroughouttheday:totalflightdurationper5minutes[median(n)]and
percentageofthedurationofeachkindrelativetothetotalflightdurationofallanimalsofthesamecategoryandsame
timeoftheday.Notethatthesepercentagescanbegivenevenifthemedianequalszero.Abbreviationsarethesameas
thoseinTable1.
Category Flights 04:30h 06:30h 08:30h 10:30h 12:30h 14:30h 16:30h 18:30h
♂ Duration 6.6(25) 22.88(24) 8.69(26) 2.72(29) 2.53(30) 0.69(30) 1.55(30) 5.12(27)
Cru&Patr 87.37% 85.76% 81.18% 39.56% 39.92% 38.42% 38.03% 44.37%
Encounter 10.87% 12.68% 15.73% 51.82% 40.92% 21.87% 0.00% 4.41%
Feed 1.76% 1.56% 3.09% 8.62% 19.16% 39.70% 61.97% 51.23%
♀ Duration 0(30) 0(30) 0.84(30) 1.91(30) 1.02(34) 1.4(29) 1.86(30) 6.38(27)
Cru&Patr 35.71% 67.80% 55.16% 56.07% 33.33% 47.54% 23.49% 55.56%
Encounter 64.29% 0.00% 0.84% 23.12% 21.16% 4.46% 0.00% 3.05%
Feed 0.00% 32.20% 44.00% 20.81% 45.51% 48.00% 76.51% 41.39%
P Duration 0(28) 0(34) 0(44) 1.13(28) 6.00(8)
Cru&Patr 100% 82.65% 95.13% 93.72% 84.94%
Encounter 0.00% 16.07% 2.46% 3.95% 13.50%
Feed 0.00% 1.28% 2.42% 2.33% 1.55%
06:30h and 10:30h, and then decreased until 14:30h (Figure 1,Table 2a). No pairs were ever
seenafter14:30h.Pairshadthreesuccessivereproductivebehavioursoverthecourseoftheday
(Table1).Afterthemalehadseizedthefemale,thepairdidnotshowanyfurthermotionforseveral
hours,butoccasionalgroomingandchangesofperch,anintervalwecalledthe“waitingphase”.
Pairsthencopulatedbetween08:30hand10:30h.Ovipositionstartednotlongaftercopulation
(1.5toc.10min,n=3observations)whilethemaleandfemalewerestillpaired.Femalesrarely
depositedeggsalone(14.29%,n=14).Non-contactguardingwasneverobserved.
Flights
Disregarding time of the day, the total flight duration per 5min was higher for males than for
femalesandpairs(Table3;one-wayANOVA:F =18.32,df =2,df =412,p <0.0001;Tukey
1 2
multiplecomparisonposthoctest:(cid:2)versus(cid:3):q =7.753,p <0.001;(cid:2)versusP:q =6.055,
p <0.001; (cid:3) versus P: q =0.2597, p >0.05). It varied significantly throughout the day for
allcategories(Table1;Kruskal–Wallistest:(cid:2):H =52.24,df =7,p <0.0001;(cid:3):H =74.42,
df =7, p <0.0001; P: H =32.11, df =4, p <0.0001; Table 2b). For males, flight duration
rapidlyincreasedfrom04:30htoreachitsmaximumat06:30handthendecreasedtoward14:30h;
it then increased again toward the evening. Females flew for longer periods at 10:30h, 16:30h
and18:30h.Pairsflewforlongerperiodsat12:30h.
Cruising flights were much more abundant than patrolling flights (respectively 93.71% and
6.29%,n=795).Mostpatrollingflightswereexecutedbymales(76.00%,n=50)buttheirrate
relativetoallflightsofbothtypes–cruisingandpatrolling–didnotdifferbetweensexes(χ2 =
1.129, df =1, p =0.288). Pairs rarely patrolled (0.69%, n=145). Taking both cruising and
patrollingflightstogether,thepatternoftheirfrequencyvariedsignificantlybetweencategories
(Table1;G-test:G=357.68,df =14,p <0.0001).Malescruisedandpatrolledmorefrequently
andforlongerperiodsfrom04:30hto08:30hthanduringtherestoftheday(Tables1,3).Females
cruisedmorefrequentlyat10:30hand18:30handlongerat18:30h.Pairscruisedmorefrequently
andforlongerperiodsat12:30h.
The pattern of encounter flight frequencies differed significantly among categories (Table 1;
G-test: G=118.54, df =14, p <0.0001). The highest frequencies of encounter flights were
observedinmales,especiallyinthefirsthalfofthedaywithapeakat10:30h,inpairsat12:30h
and,toasmallerdegree,byfemalesat10:30h(Table1).Encounterflightsrepresentedahigher
proportionoftotalflightdurationat10:30hformales(Table3).Theyweretargetedatconspecifics,
182 P.H.LambretandA.Stoquert
seldomatLestessponsa(respectively90.57%and9.43%,n=106)andneveratSympecmafusca
oratIschnuraspp.Focusingonconspecificencounteringflights,individualsweremorefrequently
targetedthanpairs(respectively79.17%and20.83%,n=96).
Feedingflightsofpairswereinfrequent,initiatedbythemale,andsometimessuccessful.The
patternoffeedingflightfrequencieswasthesameformalesandfemales(Table1;G-test:G=
19.82,df =7,p =0.0060).Thisbehaviourwasmorefrequenttowardtheeveningand,pooling
male and female durations, the time devoted per 5min to catch prey was higher at 16:30h and
18:30h(one-wayANOVA:F =12.35,df =7,df =471,p <0.0001;Table2c).Furthermore,
1 2
thedurationoffeedingflightswashigherintheeveningthantherestoftheday(Kruskal–Wallis
test, excluding 04:30 h data because of small sample size: H =67.81, df =6, p <0.0001;
Table2d).
Disturbance
Pairs were more frequently disturbed by conspecifics or triggered to display the wing threat
– by at least one member of the pair – than were unpaired individuals (respectively 76.56%
and23.44%,n=64).However,thesedisturbancesneverresultedinthebreak-upofpairs.The
patternofdisturbancewasdifferentamongcategories(G-test:G=56.91,df =14,p <0.0001):
disturbanceofpairsdecreasedfrom04:30hto14:30h,thatoffemalesincreasedfrom04:30hto
08:30handdecreasedfrom10:30untilevening,andthatofmaleswasirregular.
Postures
Males,femalesandpairschangedtheirexposuretodirectsunlight–andthereforetosolarradia-
tion–duringtheday(Figure2a).Focusingonmalesandfemalesonly,thebestmodelresultedin
Logit(E)=at2+bt +ctC+d+e(cid:3),withestimatesa =40.710(6.871),b=−48.405(8.124),
Figure 2. PosturaladaptationsofLestesmacrostigmathroughouttheday(black:♂,lightgrey:♀,darkgrey:pairs).(a)
Proportionofanimalsexposedtosolarradiation;(b)heightatwhichanimalsperchedatfirstsight(median).Samplesizes
aregiveninTable4.Exposuredataarescarcefor04:30hbecausethesunwaslowintheskyandTamarixtreesshaded
muchofthebreedingsite.From14:30h,pairsweretoorareorabsent.
DielpatternofactivityofLestesmacrostigma 183
c=3.378 (1.069), d=14.378 (2.331) and e=−1.803 (0.627), where d is the ordinate origin
and e its correction for females, the model being based on males. The significant interaction
tC suggests that males and females behaved differently: in the morning males perched more
in the sun than did females, a situation that was reversed after 12:30h. However the pattern
was similar: exposure frequency was higher in early morning, decreased toward solar noon,
then increased toward the evening. When pairs were included in the model, no reliable esti-
mates of a, b, c, d and e were obtained, probably because the size of the dataset was not
large enough. Univariate analysis suggests that pairs tended to behave differently from males
and females (G-test: G=21.97, df =6, p =0.012): their exposure frequency also decreased
from 06:30h to 08:30h but then increased toward solar noon, i.e. from copulation toward
oviposition.
RegardingtheheightofperchH (Figure2b),thebestmodelresultedinLog(H)=at2+bt +
c +d, with estimates a =5.672 (0.534), b=−6.449 (0.599), c=5.255 (0.147) and d(cid:2) =
C
−0.044(0.027),d(cid:3) =0.129(0.025),d =0,wherecistheordinateoriginandditscorrection
P
regarding the category; d =0 because the model was based on pairs and no correction to the
P
ordinateoriginwasthereforeneeded.Malesandpairsbehavedsimilarly(d(cid:2) 95%CIincluded
zero).Incontrast,dwashigherforfemales,indicatingthattheyperchedatgreaterheights.There
wasnoinfluenceoftC,indicatingthatmales,femalesandpairsfollowedthesamepattern:the
heightatwhichanimalsperchedwashigherat04:30h,decreasedtowardsolarnoon,andincreased
toward18:30h.
Ambienttemperatureandsolarradiationvariedsignificantlyduringtheday(Kruskal–Wallis
test:T :H =232.7,df =7,p <0.0001;SolRad:H=378.9,df =7,p <0.0001.Spearman
a
rankcorrelation:r =0.6269,p <0.0001,n=447)bothincreasedfrom04:30hto10:30–12:30h
andthendecreasedtoward18:30h(Table4).
Flightspeedandawareness
Flight speed was highest when temperatures were highest, i.e. 12:30h (Table 4 and Figure 3).
Flight speed was positively correlated with ambient temperature in males, females and pairs
(Spearmanrankcorrelations:(cid:2):r =0.5531,p =0.0001,n=148;(cid:3):r =0.3846,p =0.0002,
n=87;P:r =0.3705,p =0.0036,n=60).
Thedisturbingdistanceofmalesandfemalesshowedsignificantvariationsthroughouttheday,
while it remained constant for pairs; furthermore, for males, awareness was highest at 04:30h
anddecreasedtowardtheevening.Bycontrast,awarenessforfemalesincreasedtoward16:30h
(Figure4;Spearmanrankcorrelations:(cid:2):r =−0.2950,p <0.0001,n=242;(cid:3):r =0.3813,
p <0.0001,n=220;P:r =0.068,p =0.4418,n=131).
Table 4. VariationofenvironmentalconditionsthroughoutthedayforLestesmacrostigmaindividualsforwhichheight
ofperchandexposuretodirectsunlightwererecorded.Resultsaregivenasamedian.
Environmentalparameter 04:30h 06:30h 08:30h 10:30h 12:30h 14:30h 16:30h 18:30h
Ta(◦C) Height 16.3 19.5 22 24.9 26.6 23.7 23.95 21.4
Exposure 16.8 19.4 22 25 26.7 23.7 23.8 21.7
Solarradiation(W/m2) Height 36 304 653 888 925 709 398 31
Exposure 72 318 664 890 939 743 419 47.5
UVdose(μW/lumen) Height 0 0.1 0.4 0.71 0.74 0.39 0.1 0
Exposure 0 0.1 0.41 0.73 0.75 0.42 0.11 0
n Height 86 94 104 91 75 61 60 60
Exposure 13 73 97 83 61 45 41 34
184 P.H.LambretandA.Stoquert
Figure 3. FlightspeedofLestesmacrostigma:linearregressionsofflightspeedagainstambienttemperature(♂:triangle
andsolidblackline;♀:circlesanddottedline;pairs:squaresandsolidgreyline).
Figure 4. Activityperse,i.e.“awareness”(responsivenesstodisturbance)ofLestesmacrostigmathroughouttheday:
linearregressionsof“disturbingdistance”againsttimeofday.(a)Males;(b)females;(c)pairs.
Abundanceatthebreedingsiteanddetectability
Thenumberofadultspresentatthebreedingsitevariedsignificantlythroughouttheday(Kruskal–
Wallistest:H =36.53,df =7,p <0.0001)andwashighestonaverageat04:30h(Table2e).
Furthermore,thedailymaximumalwaysoccurredat04:30h,thoughsometimesthesamevalue
wasalsorecordedat12:30hand18:30h(Figure5).
Thedistancetowhichtheobserverwasabletospotanimalsvariedsignificantlythroughoutthe
day(Kruskal–Wallistest:H =32.75,df.=7,p <0.0001):detectabilitywashigherat04:30h
(Table 2f). Very few animals were spotted while in flight (1.82%, n=275), even at 04:30h,
06:30hand18:30h,whenflightactivitywasmoreintense.
Discussion
Notsurprisingly,mostbehaviourofLestesmacrostigmaatthebreedingsitewasrelatedtorepro-
duction.Thetemporalpatternofreproductionwasunimodal,whichiscommonamongOdonata
(e.g.Doerksen,1980;Utzeri&Ercoli,2004).Reproductioninvolvedthefollowingphases:seizure