Amphibians from Sabah II. Acoustic Characteristics of Three Common Anuran Species

Call characteristics of Bufo juxtasPer, Rana er2thraea and Pollpedates teucom]stax recorded at Ranau, Sabah, Northern Borneo, were analyzed with a sound spectrograph. Each of the three species possessed unique call characteristics and suggested the presence of valid preisolating mechanisms. For Bufo juxtasper, characteristics of mating calls were compared with those of release calls• The mating calls of Pol]pedates leucomlstax were suggested to differ from those of the same species from Thailand and Nepal reported by the previous authors. In my previous paper, taxonomic and natural history notes on the anurans from Sabah have been made (Matsui 1979). This paper reports the results of analyses on the acoustic characteristics of the three common species from Sabah. Few paper dealt with the call characteristics of trcpcial Asian anurans, and, to my knowledge, no reports on the frogs and toads from Sabah have been made. Materials and Methods Recordings of calls were made in mid March of 1979 at the riverside, on the grass land and along ditches of the suburbs of Ranau (for detail, see Matsui 1979). Of the three species whose calls were recorded, oviposition was ascertained only for PolyPedates leuconzNstax, and the calls for this species were regarded to the mating ones. For Rana erblthraea, the callingaggregations of the males could be considered to the breeding colonies, and females with ripe eggs were collected. Therefore, the recorded calls were considered as mating. For Bufo juxtasPer, three different kinds of calls were recorded. Among them, the two were distinct from the apparent release calls emitted when males were handled, and were considered as the mating calls. Recordings were made by a cassette tape recorder (Sony TC-D5) with an external microphone (Sony ECM-23F). The air temperatures during 1) " Con'tributiens' from "The 2nd Kyoto University Biological Expedition to Sabah", No, 2. Contributions from the "Kyoto University Biological Expedition to the Malesian Tropical Rain Forest" No. 7. recordings rangedfrom 26 to 27 C. The recorded calls were analyzed by a sound spectrograph (Kay 7029A), Results and Discussion Bufo juxtasper Forty-eight calls from four males were analysed. For the mating call, two types were recognized, and the shorter type calls were more commonly uttered than the longer type, which sometimes follows the shorter. The shorter call (Fig. 1) does not form a trilL It lasts . 07 to . 16 seconds (X=.12Å}.02), and is repeated 2.0-2.8 (X=2.2Å} .2 (SE)) times per second. Each call consists of two to four (X=3.1Å} .5) notes, each of which Iasts . 02 to ,03 seconds (X=.028Å}.OO2) and includes three to five (X==4, 2Å}.4) rather clear pulses. The dominant frequency ranges between 540-730 hz (X=622Å}46). Harmonics are not evident, and the second dominant frequency is traced between 1800-2300 hz (X=2022Å}91). The longer call (Fig. 2) is a typical trill, which is widely found in many 8 fi X4 X 'g Nur k. • 2 e . 2 . 4 . 6 . 8 l.O l,2 IA t.6 II8 8 fi "4 M 2 e . X . 4 . 6 . 8 . S.e s,2 s.4 s.6 i. 's \IME IN SEefiXeS Fig. 1. Two successive mating calls cf Bufo juxtasper (short type calls), analyzed with narrow (top) and wide (bottom) band filters. ,