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) Journal ofthe Bombay Natural HistorySociety, 105 (1),Jan-Apr2008 14-18 ADVERTISEMENT CALLS OF INDIANAND SRI LANKAN FROGS1 Mitsuru Kuramoto2 and S. HareeshJoshy3 'AcceptedMay2006 23-6-15 Hikarigaoka, Munakata, Fukuoka811-3403,Japan.Email: [email protected] 'RondanoBiodiversityResearchLaboratory, St.AloysiusCollege,Mangalore575003,Karnataka,India. Acoustic characteristics ofthe advertisement calls offive Indian and one Sri Lankan frog are described, of which three(Euphlyclishexadactylus,SylviranaaurantiacaandRamanellaobscura arereportedforthefirsttime.Temporal and spectral parameters ofthe calls are given foreach species, together with field observations ofthe environment where the males were located during calling. The results are compared with available acoustic data on the same or related species. Key words: advertisementcalls, frogs, India, Sri Lanka INTRODUCTION 24 °C; and Ramanella obscura (Giinther) in Kandy, Central Province,SriLanka,onMay30,2000at23°C.Recordedcalls Callstructuresareoneofthemostimportantattributes wereanalyzedusingAvisoftSASLabLightsoftware.Voucher offrogspecies.Themostcommonfrogcall,theadvertisement specimens have been deposited in Rondano Biodiversity call,playsanimportantroleinattractingconspecificfemales ResearchLaboratory (RBRL), St.AloysiusCollege,India. andishencespecies-specific(e.g.Sullivanetal. 1995).Thus, Generally,thecallsofmanyfrogspeciesareaseriesof we can identify frog species readily based on call pulse groups, herein referred to as ‘notes’. Some calls are a characteristics, even if we cannot observe the calling frog seriesofsingle pulses, alsoreferredtohereas ‘notes’.Thus, itself.Thisisavery useful meansofsurveying anuranfauna the calls are composed ofeither multi-pulse or single-pulse inagivenlocality,andmanymorphologicallysimilarspecies notes. Note-interval means the time between the beginning havebeendescribedbasedprimarilyonacousticdifferences ofa note and the beginning ofthe next note, and the pulse (Johnson 1959; Kuramoto 1980). repetition rateisthe numberofpulsespersec. Measurement Calls of about 40 Indian frog species have been values are expressed as the mean ± standard deviation with analyzed (Kanamadi et al. 1994, 1995; Roy 1996, 1997; sample size (n) in parenthesis. Kadadevaru et al. 2000, 2002; Kuramoto and Joshy 2001). Here, we give acoustic analyses of five Indian and one RESULTSAND DISCUSSION SriLankanfrogspecies,ofwhichcallstructuresofEuphlyctis hexadactylus(Lesson),Sylviranaaurantiaca(Boulenger)and BufoscaberSchneider Ramanellaobscura (Gunther)arereportedforthefirsttime. Malecallswereheardinpaddyfieldsfromindividuals Encountercalls ofR. obscura are also reported. floating in shallow water among the rice plants. The toads were whitish in colour at night and dark brown during the MATERIALAND METHODS day.Therewere manycallingmalesofEejervaryasp.onthe bunds ofthe paddy fields. Advertisement calls of the six frog species were Thecall waslongandconsistedofmanyfast-repeated recorded in the field using a cassette-recorder (TCM-AP5) notes (Fig. 1).Thenumberofpulses inanotewas 8.0±0.67 or MD-recorder (MZ-B10). The calls of Bufo scaber (n=19), the note duration was 0.30 ±0.03 sec, and the pulse SchneiderwererecordedinMudigere,Chickmagalurdistrict, repetitionratewas23.7±0.94pulses/sec.Noteswererepeated Karnataka, on July 9, 2005 at an air temperature of 21 °C; atanintervalof0.42±0.02sec.Thedominantfrequencywas Euphlyctis cyanophlyctis (Schneider) in Kamoor, Dakshin about3kHz,andthereseemedtobeasecondharmonicband Kannada district of Karnataka, on July 10, 2004 at 27 °C; at about 6 kHz. Euphlyctis hexadactylus (Lesson) in Adyar, Mangalore, on Kanamadi et al. (1995) reported detailed analysis of July 19, 2005 at 25 °C; Sylvirana aurantiaca Boulenger in the advertisement calls of B. scaber (as B. fergusonii Karnoor (date and temperature were the same as in Boulenger).Theircalculationsoftemporalfeaturesincluded E. cyanophlyctis)andinAralam, Kannurdistrict, Kerala,on initial stages ofcalls with notes consisting ofa few pulses, July 14, 2005 at 25 °C; Ramanella montana (Jerdon) in thus their mean values were slightly lowerthan those in the Talagini, Shimoga district, Karnataka, on July 23, 2004 at present study. The pulse repetition rate was much higher in ADVERTISEMENTCALLS OF INDIAN AND SRI LANKAN FROGS TIME (sec) Fig. 1: Three successive notes in theadvertisementcall of BufoscaberSchneider Kanamadi etal. (1995), possibly, to some extent, due to the about 0.085 sec. The dominant frequencies were about highertemperaturesduring their soundrecordings. 3.5 and 1.5 kHz, and the calls showed a weak harmonic Voucherspecimen: RBRL05070925. structure. Call structures of E. cyanophlyctis were previously Euphlyctiscyanophlyctis (Schneider) described by Roy and Elepfandt (1993), Kanamadi (1996) Calling males were observed in wetland areas with andRoy(1996, 1997).Thegeneralcall patterninthe present shallow water, together with those of Fejervarya sp. and studyresembledthatofKanamadi (1996),whodocumented Microhylaornata(DumerilandBibron). Thecallswereloud, calls consisting mainly of double-pulse notes, but differed metallic andprominent among the chorusesofthe breeding remarkably in the pulse repetition rate (c. 20 pulses/sec in aggregations ofmany frog species. Kanamadi). The calls in Assam and Meghalaya (Roy and Theentireadvertisementcallwasaseriesofshortsharp Elepfandt 1993; Roy 1996, 1997) differedfrom those inthe notes.Typically,aseriesbegan with several notescomposed presentstudy, primarily due to the greaternumberofpulses of a single pulse, followed by notes composed of double inanote (mean=7). Whetherthese conspicuous differences pulses(Fig. 2),althoughtherewerevariations. Single-pulse indicate geographical or ecological variations should be notes were repeated more rapidly than double-pulse examined in future studies. Moreover, the presence of a notes (2.28 ±0.28 vs. 1.52 ±0.15 notes/sec, n=7), and the cryptic species cannot beexcluded. pulse interval between two pulses in the latter notes was Voucherspecimen: RBRL04071140. N X > O z LU oZD LU oc Li_ Fig. 2:Two successive double-pulse notes in the advertisementcall ot Euphlyctiscyanophlyctis(Schneider) J. Bombay Nat. Hist. Soc., 105 (1), Jan-Apr 2008 15 ) N X > o LDU O LU tr 0 0.2 0.4 0.6 0.8 1 1.2 1.4 TIME (sec) Fig. 3: Twosuccessive notes inthe advertisementcall of Euphlyctishexadactylus(Lesson) Euphlyctishexadactylus (Lesson) distance. Callingmaleswereobservedinrelativelyshallowwater Thecallsbeganwithaseriesofsingle-pulsenotes(0.03- amongvegetationinafloodedwetlandnearapondpreviously 0.05 sec in duration) followed by a series of double-pulse used to observe this large species. Sylvirana aurantiaca notes(Fig.4).InthecallsrecordedatAralam,thenote-interval Boulengercalls were alsoheard at this location. betweensingle-pulsenoteswas0.66±0.12sec(n=9)andthat The advertisement call was composed of slowly between double-pulse notes was0.57 ±0.12 sec (n=15). The repeatedmulti-pulse notes (Fig. 3). The numberofpulses in lengthofasingle-pulse note was 0.03-0.05 sec andthatofa anotewas5.0±1.18(n=24),thenotedurationwas0.25±0.07 double-pulsenotewasabout0.1 sec.Thedominantfrequency sec, and the pulse repetition rate was 16.8 ±0.56 pulses/sec. wasabout3.7kHz.Anindistinctharmonicstructureandweak Thenoteswererepeatedatan intervalof 1.10±0.15 sec.The frequency modulation were recognized. firstpulseinanotewasweak,witharelativelylowdominant The advertisement calls of Sylvirana aurantiaca frequency (2.09 ±0.10 kHz, n=8). The dominant frequency resembledthoseofSylviranatemporalis Gunther)(Kuramoto ( tended to decrease from the second (2.43 ±0.09 kHz) to the and Joshy 2001), but the call length was shorter and with a lastpulse(2.29±0.11 kHz),andtherewasasecondharmonic higher dominant frequency in the former. The general band at 5.20 ±0.32 kHz (second pulse) and 4.68 ±0.17 kHz similarity in thecallstructuresofthesetwomorphologically (lastpulse). similarspecies supports theirclose relationshipas members The call ofE. hexadactylus differed completely from ofthe subgenus Sylvirana. that of E. cyanophlyctis. It was rather high-pitched, which Voucherspecimen: RBRL04071136. was unexpected considering its large body size. Also unexpectedly, male calls were heard in relatively shallow Ramanellamontana (Jerdon) waters, but not in a pond. Daniel (2002) described that the Calls were heard from individuals floating on shallow eggs of this species are thought to be laid in paddy fields. waterinpaddyfields,amongloudchorusesofFejen>aryasp.; Thespawningsiteofthisspeciesshouldbeconfirmedinfuture themaleswereobservedcallingonlyfromthebank.Thecall studies. of Ramanella montana was easily recognizable due to its Voucherspecimens: RBRL05071901, 05071902. unique tune. Like B. scaber the body colourofthis species , was whitish in the night anddarkbrown during the day. Sylviranaaurantiaca Boulenger The calls were 0.20 ±0.01 sec in duration (n=14) and In Kamoor, male calls were heard on the grassy bank composed of5-6 pulses repeated at a rate 23.4 ±2.7 pulses/ of a creek, while in Aralam they were heard among low sec(pulseinterval: 0.043±0.006sec;Fig.5a).Thedominant vegetation, together with those ofFejervarya Minervarya frequencywasabout2kHz,andtherewasalwaysaseemingly ( sahyadris (Dubois, Ohler and Biju). In Mangalore, calling continuous frequency band ofabout 0.53 kHz. Frequencies males were observed near ditches around paddy fields on a higherthan4 kHz were almost lacking. hillside, where Polypedates maculatus Gray is known to Withinthe seriesofthecommoncalldescribedabove, breed. The calls were weak and could not be heard from a there were a few calls that differed in pulse structure 16 J. Bombay Nat. Hist. Soc., 105 (1), Jan-Apr 2008 ADVERTISEMENTCALLS OF INDIAN AND SRI LANKAN FROGS N X > o 2 LLI oID LU DC Ll Fig. 4: Three successive double-pulse notes in theadvertisementcall of SylviranaaurantiacaBoulenger recorded atAralam (Fig. 5b).They containedabout 10 short pulses with apulse etal. 1993). interval of 0.02 sec and a pulse repetition rate of about Voucherspecimens: RBRL04072302, 04072303. 50 pulses/sec; frequency features were similar as in the common calls. The role ofthis call is unknown at present. Rumanella obscura (Gunther) Call structuresofR. montanawerepreviouslyreported Calls of this species was heard in ditches along a byKadadevaruetal.(1998).Intheirsonogramwerecognized mountain roadside from individuals floating on the water fiveorsixpulses;theyapparentlyenumeratedthenumberof surface. Nootherfrogspecieswasobservedintheseditches, peaks in a waveform envelope as the pulse number. The whereas many Philautus species were heard calling among dominant frequency band was about 2 kHz in their report nearby bushes. and no higher frequencies were reported as in our results. The calls were 0.21 ±0.04 sec in duration (n=12; However, a rather distinct first pulse and clear fine harmonic Fig. 5c), consisting of 7-17 (1 1.9 ±2.9) indistinct irregular bands in their sonogram were not obvious in our sonograms. pulses.The pulse interval was0.02 ±0.003 sec andthepulse Differing from R. montana, R. variegata (Stoliczka) seems to repetition rate was 51.7 ±7.5 pulses/sec. The dominant haveasingle-pulsedcall ofabout0.2 secduration (Kanamadi frequency band was about 2.6 kHz with a lower frequency 1 Bombay Nat. Hist. Soc., 105 (1), Jan-Apr 2008 17 : . ADVERTISEMENT CALLS OF INDIAN AND SRI LANKAN FROGS Fig. 6: Encountercallsof Ramanella obscura(Gunther) in breeding aggregations band of about 0.75 kHz. The calls were emitted at about (Fig. 5b). Ramanella nagaoi Manamendra-Arachchi and 0.96 sec intervals. Pethiyagoda, anotherSri Lankan speciesforwhichacoustic Inbreedingaggregationswheremanymaleswereheard data are available, has a completely different call callingincloseproximity,higherfrequenciesbecameevident (Manamendra-Arachchi and Pethiyagoda 2001). (Fig. 6). This call is apparently an encountercall, which has No voucher specimens. an agonistic function. Ramanella obscura resembled R. montana in call ACKNOWLEDGEMENTS duration and frequency constitution, but differed in the number ofpulses. Regarding the number ofpulses, the call We thank P.K. Bhat andT.B.R. Hegde for theirhelp in ofR. obscura resembled the multi-pulse call ofR. montana thefield. REFERENCES Daniel, J.C. (2002): The Book of Indian Reptiles and Amphibians. Kanamadi, R.D., C.R. Hiremath & H. Schneider (1995): Vocalization BombayNatural History Society, OxfordUniversity Press. oftropicalIndiantoads,BufomelanostictusandBufofergusonii. Johnson, C. 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Bombay Nat. Hist. Soc., 105 (1), Jan-Apr 2008