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The Western Ghats region of India has been identified as one of the 18 biodiversity hot spots of the world (WCMC 1988), and harbors 205 species of amphibians (Daniels 1992). Kaloula pulchra is a medium-sized burrowing frog (mean male SVL = 67.3 mm, N = 10) distributed in parts of Western Ghats. Although K. pulchra is a common microhylid of this region, we have limited knowledge about this species from the Western Ghats. In particular, very little is known about its reproductive biology. We investigated the breeding period and advertisement call of this species.
Both field observations during the breeding season and characterization of the male call parameters were conducted near Dharwad (15 deg 27'N, 75 deg 05'E). From 1989 to 1997, we recorded male calls with directional microphones (AKG, D- 707/190 C, D- 1000 I) and tape recorder (AKAI AJ 490 FS, 4.8 cm/s) at water temperatures of 19-21 deg C and relative humidities between 90 and 93%. We used a LUTRON SL 4001 SPL meter (fitted with Bruel & Kjaer multi-function acoustic calibrator, 4226) to measure the sound pressure level (re 20 #Pa, "fast" root-mean-square [RMS], C weighing) from a distance of 1 m. Calls of 20 males were analyzed by the acoustic analyzer computer program MOSIPO(R) spectro analysis V6 8, 41/89, MEDAV GmbH, at Zoological Institute, University of Bonn, Germany; statistical analysis was carried out with Statgraphics (STSC, Statistical Graphic Corp., Knoxville, Tennessee, USA).
Calling activity began after the first two to three heavy premonsoon showers (April/May) during 1990, 1991, 1992 and 1996. When the pre-monsoon rains failed to occur during 1993, 1994, 1995, and 1997, the calling began with the onset of monsoon rains (June/July) and continued until August. Observations over a period of eight years indicated that the males emit the advertisement call from April to August. During the same period amplected pairs also were observed in the field. Hence, in the absence of reports on the gonadal cycles, we suggest that April to August may be the breeding period of K. pulchra. The calls were given while males floated on the water surface. Calling was in chorus, however adjacent calling males alternated their calls (N = 50). Advertisement calls were emitted in series with variable...