*Author ([email protected]) for correspondence Israel. theNegev,University of SedeBoqerCampus84990, MidreshetBen-Gurion, Energy Research, Research, Jacob Ben-Gurion Blaustein Institutesfor Desert Ecology, Desert Environmental SwissInstitutefor and Dryland of Department 3028 Received 22November 2013;Accepted10June2014 1 echolocating batsintotwogroups:‘loud’ aerialinsectivoresthat specialised ears(Griffin, 1944). environment andreturningechoesaredetectedbythe ’ Teeling, 2006).Thissound isreflectedbyobjectsintheir either thenoseormouth(SchnitzlerandKalko,2001;Jones and ultrasound callsbypushingairthroughthelarynxandout outgoing signal.Allecholocatingbats(except can controlthesensoryinputtheyreceivebymanipulating the cetaceans (Griffin, 1958;Thomas etal.,2004).Echolocatinganimals returning echoes,asusedbymostmembersofChiropteraand some emit echolocationpulsesandgainsensoryinformationfromthe more important.Anothersolutionisbiosonar, wherebyindividuals environments, othersensessuchasolfactionorhearingbecome is oftenthedominantsense;however, foranimalsinpoorlylit with theirenvironment,particularlyregardtoforaging.Vision All animalsrequireaccuratesensoryinformationinordertointeract Foraging guilds,Sourcelevel KEY WORDS:AcousticTracking, Arthropodprey, Echolocation, level tothosetypicalofatrueaerialhawker. switch betweenforagingguildswiththerespectivechangesinsource insects onthewing,inpresentstudyweshowafullbimodal Although whisperingbatshavebeenknowntoopportunisticallycatch from passivegleaningtocapturingairborneinsects(aerialhawking). species werecapableofflight.We concludethatthebatsswitched indicated thattheirdietdiffered frompreviousstudiesandthatprey (compared with75 source levels,wherebatscalledatameanof119 found differences inallvariableswiththestrongestdifference in gleaning individualspreviouslyrecordedusingthesamesetup.We speed, callduration,pulseintervalandsourcelevelswiththoseof foraging anddrinkingsitescomparedtheirflightheight, Using anacoustictrackingsystem,werecordedindividualsflyingat whispering batpreyingonterrestrialarthropodssuchasscorpions. Otonycteris hemprichii,hasbeensaidtobeapassivegleaning the amplitudeoftheirecholocationcalls.Thedesertlong-earedbat, in multiplewaysandothershavedemonstratedlimitedflexibility aerial hawkersorwhisperinggleaners.Somebatspeciescanforage Echolocating batshavehistoricallybeenclassifiedaseitherloud Talya D.Hackett from gleaningtoaerialhawkinginthedesertlong-earedbat A whisperingbatthatscreams:bimodalswitchofforagingguild RESEARCH ARTICLE © 2014.PublishedbyTheCompanyofBiologistsLtd|JournalExperimentalBiology(2014)217,3028-3032doi:10.1242/jeb.100362 INTRODUCTION ABSTRACT School of Biological Sciences, University of Bristol,BristolBS81UG, UK. BiologicalSciences, University of School of Recording frombatsinthehand,Griffin (Griffin, 1958)classified dB 1 , CarmiKorine peSPL whengleaning).Batfaecalanalysis 2 and MarcW. Holderied Rousettus) emit

dB peSPL 2 Mitrani 1, whispering bats, emitcallslouderthanpreviously thought(Brinkløv M. macrophyllum al., 2005;Nørumet2012). Followingtheinitialdiscoverythat has beenwelldocumented(Boonman andJones,2002;Holderiedet 2010) andthedecreaseinsource levelsduringthetarget approach decreases callintensityduring the landingapproach(Koblitzetal., produced bybatsthanpreviously understood. Miller andTreat, 1993).Thereisalsogreaterflexibilityinthecalls between 77and102 bats (e.g.gleaning al., 2005;SurlykkeandKalko,2008),whilequieterpassivegleaning and Jones,2002;HolderiedvonHelversen,2003; et (peSPL) (Surlykkeetal.,1993;JensenandMiller, 1999;Boonman the rangeof103to137 of thebat).Aerial-hawkingbats(e.g.Eptesicus of thesoundintensityat10 allowed formoreaccuratemeasurementsofsourcelevels,ameasure species areabletousedifferent tacticswhennecessary. foraging guildsinbatsarenotmutuallyexclusiveasatleastsome al., 1991;SchummetWeinbeer etal.,2013).Hence, including aterminalbuzz,dependingonthetacticinuse(Krullet macrophyllum, whichwilluseoromitdistinctecholocationphases pulse durationandinterval), emarginatus, whichchangethetemporalstructureoftheircalls(e.g. tactics (Ratcliffe andDawson,2003).Thisisalsotrueof ( labelled asanaerialhawker( and Barclay, 1994).Two furtherspeciesof echolocation callschangedependingonthemodeofattack(Faure aerial-hawking flyingmoths,andthedurationfrequencyoftheir evotis strategies frommultipleguilds(Fenton,1990).Forexample, This istruealsoforinsectivorousbats,whichmaychooseforaging have dietsconsistingofbothnectarandarthropods(Pyke,1980). 2012). Hummingbirds(Trochilidae) andhoneyeaters (Meliphagidae) (wave washing)andhuntinginopenwater(PitmanDurban, strategies includingcreatingwavesthatknocksealsfromicefloes conditions. Orca( switch strategiesdependingonpreyavailabilityorenvironmental 1990). of thebatsineachguildconformtosimilarproperties(Fenton, water surfaces(Norberg andRayner, 1987).Theecholocationcalls echolocation (activegleaners),andtrawlersthatcatchpreyfrom listening forprey-generatedsounds(passivegleaners)orby gleaners thattakepreyoff thesubstrate,whichtheydetectbyeither including aerialhawkersthatcatchflyinginsectsonthewing, More recently, batshavebeen classifiedintobroadforagingguilds nectarivores, carnivoresorgleaninsectsoff theground/vegetation. catch insectsonthewingand‘whispering’ batsthatarefrugivores, * M. septentrionalis Modern advancesinultrasoundrecordingtechnologyhave However, foragingmodesarenotalwaysfixedandanimalsmay is equallyadeptatgleaningmothsfromthesubstrateand ), arebothcapableofcatchinginsectsusing Orcinus orca ) willuseavarietyofhunting

dB Myotis and peSPL (Faure etal.,1990;Faure1993;

dB Artibeus jamaicensis

cm fromthesourceofacall(i.e.mouth spp.) onlycallwithasourcelevelof peak-equivalent soundpressurelevel M. lucifugus ) andtheotheragleaner Myotis , bothsaidtobe spp.) emitcallsin , onetraditionally Eptesicus fuscus Macrophyllum Myotis M.

The Journal of Experimental Biology occasion, 106.6–142.9 frontal on-axiscallswere 124.2±9.0 al., 2011), havingadifferent flightheight( typical searchpatternasdescribedinHolderiedetal.(Holderied et 1.Thebatsrecordedheredidnotflyinthe are presentedinFig. and willrefertoitasthedrinkingsite. behavioural context,sowedidnotpoolZefirawiththeothersites (Holderied etal.,2011). foraging: drinking–gleaning: al 1)andflightspeed( Table gleaning attacksandintherangeoftypicalaerialhawkers. source level,whichweexpecttobesignificantlyhigherthanduring call behaviour, namelycallduration,pulseintervaland,inparticular, speed. We alsoexpectthataerial-hawkingindividualswillaltertheir change theirflightbehaviourwithregardtoheightand hawking. We thereforepredictthataerial-hawkingindividualswill between foragingmodes,namelypassivegleaningandaerial observations). pattern thanistypicallyreported(T.D.H. andC.K.,personal 75.25±6.9 harmonic echolocationcallstypicalofawhisperinggleaningbatat microphone arrayandrecordedfrequencymodulated(FM)multi- hemprichii surface. Holderiedetal.(Holderiedal.,2011) recorded environment withechoescomingfromanon-uniformground al., 2011); thusthesebatsforageinabackground-cluttered flight 3–7 consumed whilethebatadoptsaslow, glidingandwidelycircling (40–100 Qumsiyeh, 1995).GleaningO.hemprichii long ears,lowwingloadingandaaspectratio(Gharaibeh 2011; Hackettetal.,2013).Aswithmostgleaningspecies,ithas Fenton etal.,1999;KorineandPinshow, 2004;Holderiedetal., environments (Arlettazetal.,1995;GharaibehandQumsiyeh, feeds primarilyonnon-aerialarthropodsindry, sparselyvegetated of 118.8±7.7 a battypicallyconsideredtobe whisperingwithanoverallmean All recordedcallswereofahigher sourcelevelthanexpectedfor by palm garden).We didnotrecordorobserveanydrinkingattempts Moshav Hatzevapoolareaand32fromthedate from foragingsites(oneNahalBitaron,seventhe path; range:4–76):20pathsfromZefira(naturalpool)and40 paths fromfourdifferent sites(mean:15.38±11.25 callsperflight In total,werecorded849individualecholocationcallsin60flight during open-spaceforaging. semi-cluttered foraging,withtheloudestcallsbeingproduced levels inM.macrophyllum et al.,2009),Brinkløval.(Brinkløv2010)foundthatsource RESEARCH ARTICLE drinking–foraging: HSD; drinking–gleaning: both thedrinkingsiteandforagingsitesflewhigher(Tukey’s Flight behaviourFlight RESULTS Echolocation behaviour Two typicalflightpathsfrom foragingsitesinMoshavHatzeva Here wetestthehypothesisthat Otonycteris hemprichii O. hemprichii cm) andlandfor2–5

O. hemprichii dB m abovetheground(Arlettazetal.,1995;Holderied P gleaning tetheredscorpionsfromthegroundusinga =0.34; Table dB dB peSPL. However, anecdotalevidencesuggeststhat,on peSPL; 86calls from32individuals)andthemean peSPL (range:93.5–140.5 at Zefira,butcannotfullyexcludethisasthe P P =0.004, foraging–gleaning: =0.001; Table calls louderandadoptsadifferent flight Peters 1859isadesertpassivegleanerthat

1) thanduringgleaningatParkSapir F increased fromflyinginaflightroomto 2,120 P <0.001, foraging–gleaning: =13.893,

s tocatchprey, whichare then

1) andslower(Tukey’s HSD; O. hemprichii P <0.001; Table F

fly closetotheground dB 2,120

dB peSPL). Themean P =17.577, <0.001, drinking– peSPL (range: can switch

1). Batsat P P <0.001; =0.01, O. gleaning: and louder(Tukey’s HSD;drinking–gleaning: drinking–gleaning: drinking andforagingsites,butcallswerelonger(Tukey’s HSD; source levels(Tukey’s HSD; and sourcelevels(F interpolated inB. approach orabandonedbuzz.Sixteencallsthatcouldnotbelocalisedwere B theredcallsareinspectrogramFig. circles arethefirstcallinflightpath.(A)Searchflight.(B)Aerialattack.In call. Thegreypathsarethe2Dprojectionsoforiginal3Dpaths.solid the MoshavHatzevadategarden. contained 75% Hymenoptera and25%Lepidoptera. Lepidoptera, IsopodaandColeoptera each–andonepellet consisted ofonlyoneprey type –100%byvolumeDiptera, on threenightsattheMoshav Hatzevasites.Fourofthepellets We collectedfivefaecalpelletsfromindividual females, caught foraging sitesandwhilegleaninginpulseduration( overall echolocationcallsdiffered betweenthedrinkingsite, (range: 109.7–132.3 lateral (perpendiculartoon-axis)callswere119.8±6.4 Fig. difference inpulseduration(Tukey’s HSD; sequence decreasingto18 approach phaseofanaerialattack,withthepulseintervalin this consisting ofshort-durationFMsweeps,resembledthat the ground (Fig. abandoned aerialattackonaninsectataheight3.5 Table HSD; drinking–gleaning:P but atthedrinkingsitepulseintervalwasgreater(Tukey’s gleaning andattheforagingsite(Tukey’s HSD; Individuals showednodifference inthepulseintervalbetween P Diet analysis <0.001; Table

.Two three-dimensionalflightpathsof 1.

1). Oneoftheflighttrajectoriescontainedanapparent Z (m) Z (m) 2.0 2.5 3.0 3.5 4.0 10 12 14 16 4 6 8 P 6− 2 2 6 4 2 0 −2 −4 −6 The JournalofExperimentalBiology(2014)doi:10.1242/jeb.100362 . . . . 2.5 2.0 1.5 1.0 0.5 0 B A <0.001; Table 1B). Thecorrespondingecholocationbehaviour,

1), pulseinterval( ● ● ● ● ● ● ● ● ● ● P 2,120 ● ● ● ● ● ● ● ● dB ● ● ● ● ● ● ● ● ● <0.001, foraging–gleaning: ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● X (m) ● ● ● ● ● ● ● ● =635.39, ● ● ● ● ● peSPL; 68callsfrom24individuals).The ● ● X (m) ● ● ● ● ● ● ● ● ● ● ● ● ● ●

● ● ●

● ● ● ● 1) thancallsrecordedwhilegleaning. ● ●● ● s(i.2). (Fig. ms ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● <0.001, drinking–foraging:P ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● Points areeacharecordedecholocation ● ● ● ● ● ● ● ● ● ● ● ● ● ● P P ● ● ● ● ● ● F <0.001; Table =0.29; Table ● ● ● ● ● ● ● ● 2,120 ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● ● =10.37, ● ● ● ● ● ● −5 ● ● Otonycteris hemprichii ● ● ● ● ● ● ● ● 0 ● ● ● ● ● ● ● ● ● ● 1 ● ● ● ● ● ●●●●● ● ●

● ● ● ● 5 2 representingalate ● ● P ● ● ● ● ● ● 2 P ● ● ● ● =0.29; Table ● ● 10 P <0.001, foraging– P

P Y (m)

1). Therewasno 1) betweenthe 3 <0.001; Table <0.001; Table =0.96; Table Y (m) 15 F 4 2,130 20

m fromthe

dB 25 5 =33.064, <0.001; peSPL 6

3029 1) or at

1),

1) 1)

The Journal of Experimental Biology out thepossibilitythattheseweregleanedfromsubstratesratherthan feeding atleastpartlyonwingedinsects,althoughthisdoesnotrule in themajorityoffaecalpelletsindicatesthat that Thus itisinlinewithpreviousresearchonbats’ foragingadaptability shown tocatchinsectsonthewingopportunistically(Howell,1974). In fact,evenprimarilyfrugivorousandnectarivorousbatshavebeen most batswillcatchinsectsonthewingwhenpossible(Fenton,1990). Ratcliffe andDawson,2003;Levinetal.,2009),itislikelythat been showntousemultipleforagingtactics(FaureandBarclay, 1994; and pre-buzzcallintervals(BrittonJones,1999).Otherbatshave a terminalbuzzofanaerial-hawkingbat,butsimilartolate-approach interval to18 et al.,1995;Fenton1999;Daniel,2005).A decreaseincall while gleaning,anddietarydifferences frompreviousstudies(Arlettaz levels) behaviourbetweenbatsrecordedhereandthose in flight(speedandheight)echolocation(durationsource 3030 RESEARCH ARTICLE calls ofasecondindividual arevisible. recordings ofgleaning individuals(Holderiedetal.,2011). Inthetoprow, faint short-duration frequencymodulated sweepisconsistentwithprevious applied afiniteimpulseresponsefilter withtheinversenoisespectrum.The in theMoshavHatzevadategarden. abandoned buzzecholocationcall sequenceofOtonycterishemprichii 100%, overlap98.43%,windowflat top)ofalateapproachor Fig. feeding buzzataheight3.5 hawker, assupportedbyalateapproachorpotentialabandoned Our resultsindicatethat Different superscriptsineachcolumnindicatesignificantdifferences (inallcases Foraging sites Drinking site Behavioural context sites indesertareasofIsrael Table DISCUSSION Frequency (kHz) 2.19±1.0 23 Gleaning

.Spectrogram (fastFouriertransformwindowsize=1024,frame 2. 25 50 75 25 50 75 25 50 75 O. hemprichii 1. Mean±s.d.flightandecholocationparametersforOtonycterishemprichii

ms isslightlylongerthantypicalpulseintervalsduring is abletoaerialhawk.Thepresenceofinsectwings 03.61±2.1 5.35±4.2 40 20 N O. hemprichii

m fromtheground,consistentdifferences lgthih m Flightspeed(m Flight height(m) Time (s) To reducebackground noise,we c b a can operateasanaerial 2.32±1.0 2.68±0.9 3.52±1.3 O. hemprichii 100

ms b b a

s are − 1 us uain(s us nevl(s Sourcelevel(dB Pulseinterval(ms) Pulseduration(ms) ) P Molossus flight speedthanduringgleaning. Aerial-hawkingbatsofthegenus hemprichii agility (Gardineretal.,2008;Gardiner etal.,2011). Interestingly, aerial hawking,whichisassociated withhigherflightspeedsand such asO.hemprichii slower flight(Norberg andRayner, 1987).Hencealong-earedbat carry heavyloads.Butthesefeaturesincreasedragandarelinked to detection offaintsoundcuesandlowwingloadingtoallowthem to foraging mode.Gleaningbatsusuallyhavelongearsfor the pressure levelofitscall. O. hemprichii in thesamespecieswithoutaconcurrentchangehabitatclutter, and knowledge showingalinkbetweensourcelevelandforaging mode of passivegleaningandaerialhawking.Thisisthefirststudyto our hemprichii changes inflightandecholocationbehaviour, weconcludethat from themeanofallcallsasusedhere.Inconjunctionwithconcurrent better comparison,andeventhelateralcallswereonly1 personal observation),lateralratherthanon-axiscallsmayprovidea ears pointingforwardwhilesearchingforterrestrialprey(M.H., (Holderied etal.,2011). Actually, as measurements andthosefromgleaningindividualsinHolderiedetal. would haveartificiallyinflatedthesourceleveldifference betweenour calls. On-axisrecordingswere5 al. (Holderiedetal.,2011), weincludedallcalls,andnotjuston-axis Holderied, 2007).UsingthesameselectioncriterionasHolderiedet towards amorenarrowband,lower-frequency call(Jonesand from thisspecies’ typicalshort-duration,broadband,FMsweep that mightservetoincreasedetectionrangeevenfurther, i.e.away same level.Interestingly, thereisnoapparentchangeincalldesign hemprichii between 120and130 2012). Thetypicalon-axissourcelevelsofaerial-hawkingbatsare recorded duringtarget approachin environments (Brinkløvetal.,2010)aswellthe30 reported forM.macrophyllum differences. Thisadaptabilityisconsiderablygreaterthanthe11 (Holderied etal.,2011), sothisisnotanartefactofexperimental methods asusedtodeterminegleaning of 141.We usedthesametrackingequipmentandidenticalcalculation those previouslyreportedfor 1995; Fentonetal.,1999;Daniel,2005). Diptera, Hymenoptera,LepidopteraandOrthoptera(Arlettazetal., Solifugidae, ScorpionidaeandAraneae),onlyoccasionally higher prevalenceofnon-flyingarthropods(e.g.Coleoptera, taken inflight.Previousstudiesonthisspecies’ diethavefounda are flyingslower thantheoptimalspeed predicted bytheir manoeuvrable flightinconfined spaces,presumablybecausethey than 43 (Holderied etal.,2011). Thisspeciesadjustsitssourcelevelbymore <0.01). GleaningdataarefromHolderiedetal.(Holderiedal.,2011). 3.80±1.0 4.13±0.8 2.46±1.1 There aretrade-offs inmorphology whenspecialisinginone The sourcelevelsthatwereporthereareconsiderablylouderthan

dB, correspondingtoanincreaseinsoundpressurebyafactor b b a have greatermetaboliccosts associatedwithmore is indeedabletoswitchbetweenthetwoforagingmodes in therecordingspresentedherearecallingatalmost The JournalofExperimentalBiology(2014)doi:10.1242/jeb.100362 recorded hereduringaerialhawking adoptedaslower while gleaning,atthedrinkingsiteandforaging shows thelargest knownadaptability inthesound

dB (HolderiedandvonHelversen,2003); that specialisesingleaningislessadaptedto 136.16±45.1 216.25±93.0 131.6±82.0

dB louder, sorejectingoff-axis calls a moving fromopentocluttered O. hemprichii Myotis daubentonii a b O. hemprichii O. hemprichii 116.8±5.3 119.0±7.7 75.3±6.9 during gleaning looks downwith a (Nørum etal., dB difference b b source levels

dB different

peSPL)

dB O. O. O.

The Journal of Experimental Biology prey byO.hemprichii common inthestudyareaand,whenpresented,arereadilytakenas active. BothS.mauruspalmatus nights, whenambushpredatorssuchasdesertscorpionsareless to alternativepreyandthusadifferent foragingmodeonmoonlit behaviour. However, itispossiblethat this study, soitisunlikelythatthiswasaffecting thescorpions’ was initsfirstquarterandsettingbetween22:0000:15 tend toambushfromundervegetation(Skutelsky, 1996).Themoon ( Additionally, onmoonlitnights,adultcommonyellowscorpions village gardenswherewerecorded(Hackettetal.,2013). habitats andrarelyinartificialsuchasthedatepalms Indeed, different foragingmodeintimesofscarcityitstypicalprey. artificial irrigationorattacksdifferent preyandthenadoptsa is thereforepossiblethat more inactiveduringdryconditions(ShachakandBrand,1983).It scorpions (e.g.Scorpiomauruspalmatus),forinstance,become days, soitislikelythatusualpreyitemswerescarcer. Desert exceptionally hotanddrysummerwithmultiplerecord-breaking availability. Thetimeofrecording wastowardtheendofan adopting anotherischangesinenvironmentalconditionsorprey in ourstudyweremostlikelyexclusivelyaerialhawking. flying searchtactics(Holderiedetal.,2011). Thus,theindividuals their echolocationbehaviourthanpreviouslyunderstood. in anybatspecies,indicatingthatperhapsbatsaremoreflexible The malleabilityinsourcelevelsisthemostextensivechangeseen doing sotheydrasticallyalterboththeircallandflightbehaviour. hemprichii behaviour andwedidnotobserveanyclassic flight pathsconsistedofloudcallsthatareatypicalusualgleaning 2007). However, itdoesnotappearthatthisiswhatwerecorded;all aerial hawkingdependingonpreyavailability(Todd andWaters, for instance, hawking fromtheirnormalforagingmodeiftheydetectflyingprey; chase moremanoeuvrableflyingprey. movements of We usedanarray of2×4microphones(Knowles, BT1759) totrackflight 30°49′ Deserts, Israel:onenaturaldesertareawithnowater(NahalBitaron, We collecteddatainAugust2010atfoursitestheAravaandJudean hemprichii and Holderied,2012).Thesloweraerial-hawkingflightof physiology andincreasedcentripetalaccelerationincurves(Voigt RESEARCH ARTICLE which waslocatednexttoaswimmingpool(30°46 Study site MATERIALS ANDMETHODS Flight andecholocationFlight behaviour the otherinanorchardofdatepalms(30°46 30°20′ natural poolwhereweobservedotherspeciesofbatsdrinking(Zefira, from NahalBitaron,arelativelyopensitein200 flying lessthan5 (Holderied etal.,2011) recordedsourcelevelsofgleaning Hatzeva arelocated~20 in MoshavHatzevawith8 bed) with10 Buthus occitanusisraelis One possiblereasonforabatadaptedtooneforagingmode It isthoughtthatmostbatswillopportunisticallyswitchtoaerial The evidencethatwepresenthereindicatesnotonlydoes 4N, 35°16′ 00N, 35°17′ O. hemprichii m betweenthetreeandcliff edge,tothedatepalmorchard might thusallowforabruptinitiationoftightturnsto switch foragingmodestoaerialhawking,butwhen O. hemprichii Myotis daubentonii 58E); twovillagegardensinMoshavHatzeva,oneof m fromverticalstructures,butsitesrangedinopenness 00E). Allsitescontainedbackgroundclutterwithbats (Holderied etal.,2011). in theregionaretypicallyfoundnatural

km fromParkSapir, whereHolderiedetal. O. hemprichii

m betweentrees.NahalBitaronand Moshav ) arelessactive,andthosethatactive as describedinHolderied andvonHelversen switches betweentrawlingand and enters different habitatswith O. hemprichii B. occitanusisraelis ′ 11N, 35°16′

m widewadi(dryriver ′ O. hemprichii 08N, 35°16′ O. hemprichii. also switches 39E); andone

h during 44E) and low- are O. O. We calculatedsourcelevelsfrom thefundamentalfrequencyindB the sametrackingapparatus;seetheirpaperforfurtherdetails. echolocation behaviourof Germany). Holderiedetal.(Holderiedal.,2011) measuredflightand Tokyo, Japan,withQuadmicamplifier, RME,AudioAG,Haimhausen, with acalibratedmicrophone(CO-100K,SankenMicrophoneCo.Ltd, to startoftwoconsecutivecalls),weadditionallyrecordedecholocationcalls speed. To measuresourcelevels,calldurationandpulseinterval(fromstart Erlangen). Fromtheseflightpaths,wedeterminedheightand microphones usingthecustom-writtensoftwareBatSonar(Universityof the timeofarrivaldifferences ofecholocationcallsbetweenthese (Holderied andvonHelversen,2003).We constructedflightpathsbasedon Dryland ResearchSpecificSupportAction Plan(toT.D.H.). C.K.), TheExplorersClubExploration Fund (toT.D.H.) andEuropeanCommission This studywassupportedbytheIsraeli MinistryofScienceandTechnology (to M.W.H. and capturelicenses.T.D.H. wrotethepaperwithassistancefromC.K.and and analysedthedata.M.W.H. providedequipmentandC.K.accesstofieldsites T.D.H., C.K.andM.W.H. conceivedtheresearchideaandconductedfieldwork The authorsdeclarenocompetingfinancialinterests. Department ofDesertEcology. Lauren Holtassistedwithdatacollection.Thisispublicationno.842oftheMitrani using R2.7.1(RFoundationforStatisticalComputing). et al.,2011). Allstatisticaltestswerecomputedandgraphscreated sites comparedwithgleaningdatapublishedinHolderiedetal.(Holderied duration, pulseintervalandsourcelevelsbetweenthedrinkingforaging post hoc allowing theuseofparametricstatistics.We usedanANOVA withTukey all parameters.Alldatawerenormallydistributedandhomoscedastic, individual flightpaths,wecalculatedameanvalueforeachpath To removepseudoreplicationcausedbydifferent numbersofcallsin Israel NatureandParkAuthority. by volume. remains andreportcontentsaspercentageofarthropodtype(oftenorder) Leica Microsystems,Wetzlar, Germany),recorded anyidentifiableinsect Hatzeva. We inspectedallpelletsvisually(LeicaEZ5OEMmicroscope, droppings fromfivebatscaughtinmistnetsatsiteswithinMoshav On nightswhenwewerenotrecordingflightpaths,collectedfaecal retz . adie,G,Ksbkv . ilt .M,Rbn .adZm,J. Zima, and S. Rybin, J. M., Pillet, E., Kasybekov, G., Dandliker, R., Arlettaz, was ±20 only callsina±20 ±20 comparisons); (2)onlythosecallson-axis,i.e.wherethemicrophonewas including thosethatwerenoton-axis(theseusedforthestatistical than fourcallsandemployedthreedifferent selectioncriteria:(1)allcalls following Bazley(Bazley, 1976).We analysedallflightpathswithmore Yverdon-les-Bains, Switzerland),wecompensatedforspreadingloss temperature andhumidity(SkywatchGEOSNo.11, JDCElectronicSA, the calibratedmicrophonefromflightpathsand,usingmeasured using thesonarequation(Møhl,1988).We determinedthebats’ distanceto − Calculation of source levels source Calculation of References Funding Author contributions Competing interests Acknowledgements Statistical analysis Diet analysis 110 (Chiroptera, ). (1995). Feedinghabits ofthelong-eareddesertbat, captureswereconductedunderlicenseno.34615giventoC.K.bythe deg inazimuthandelevationrelativetoflightdirectionvector;(3)

deg inazimuthrelativetotheflightdirectionvector. deg inelevationandbetween70110 tests todeterminedifferences inflightheight,speed,call The JournalofExperimentalBiology(2014)doi:10.1242/jeb.100362

deg rangeoflateraldirections,i.e.wherethemicrophone O. hemprichii J. . 76, 873-876. gleaning tetheredscorpionsusing

deg orbetween tncei hemprichi Otonycteris −

70 and peSPL 3031

The Journal of Experimental Biology esn .E n ilr L.A. Miller, and M.E. Jensen, oel D.J. Howell, G. Jones, and S. Robson, S., Parsons, M.B., Fenton, C., Korine, M.W., Holderied, odre,M .advnHlesn O. vonHelversen, and M.W. Holderied, odre,M,Krn,C n oiz T. Moritz, and C. Korine, M., Holderied, 3032 RESEARCH ARTICLE akt,T . oie .adHleid M.W. Holderied, and C. Korine, T. D., Hackett, D.R. Griffin, rto,A .C n oe,G. Jones, and A.R.C. Britton, rnlv . ak,E .V n ulke A. Surlykke, and E.K.V. Kalko, S., Brinkløv, E.N. Bazley, ona,A n oe,G. Jones, and A. Boonman, rnlv . ak,E .V n ulke A. Surlykke, and E.K. V. Kalko, S., Brinkløv, ail S. Daniel, ar,P . ulr,J .adDwo,J.W. Dawson, and J.H. Fullard, P. A., Faure, R.M. Barclay, and J.H. Fullard, P. A., Faure, etn M.B. Fenton, R.M. Barclay, and P. A. Faure, etn .B,Samn .adMkn D. Makin, and B. Shalmon, M.B., Fenton, adnr .D,Dmtids . elr,W .adCd,J.R. Codd, and W. I. Sellers, G., Dimitriadis, J.D., Gardiner, hrie,B .adQmie,M.B. Qumsiyeh, and B.M. 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