Bioacoustics of Physalaemus irroratus

Call A ( Fig. 11 A–F and 4H). We examined two recordings, a total of one minute, with 29 calls from two males. Most of these calls were measured (see Table 2 ). Call duration varies from 0.489 to 0.954 s . The call rise and fall durations are similar; both are usually linear-shaped. In some calls, the rise and/or fall can be more abrupt and have a logarithmic shape. The amplitude peak is at around the middle of the call duration, except in calls with very few pulses ( e.g. , two pulses). Since both rise and fall are similar in slope and duration, the envelope of the call is fairly elliptic ( Fig. 11A, C ). More than 50 % of the call energy is concentrated in 38 % of the call duration around the amplitude peak. The call has a strong PAM (with silence intervals present between pulses; Fig. 11 A–F). The rate of the PAM is ca. 6 Hz, forming ca. four pulses throughout the call. Usually, pulses have an abrupt rise, shorter than fall, which is more gradual, with amplitude peak at the beginning of the pulse ( Fig. 11A, C, D ). However, the first pulses of the longer calls have rises similar to falls and the amplitude peak is at the middle of the pulse. In some calls, the last pulse is clearly shorter than the others. There is a long silence interval between pulses, ca. 5.5 times the pulse duration ( Fig. 11A, C, D ). Some pulses have an internal slight PAM. The call has a harmonic series ( Fig. 4H ). The fundamental frequency is ca. 400 Hz and this band can be present with low energy or absent in the audiospectrograms. The wave periods are regular and then the harmonics are clear throughout the call. However, subharmonics, deterministic chaos, and jumps of the fundamental frequency are observed at the beginning and at the end of the pulses, or even in the entire pulse (usually the last one). Short pulses can be shown as broadband clicks (instantaneously high sound-pressure effect; see Littlejohn 2001 ) in audiospectrograms at broad filter bandwidth (first pulse in Fig. 11A ). The dominant frequency varies from ca . 1250 to 1720 Hz ( Fig. 11B ). The dominant harmonic varies from the second to the ninth, but it is usually the third or fourth. There is no clear shift in the relative energy among the bands throughout the call. Most of the call energy is between 1300 and 2000 Hz (often, three harmonics). The frequency bands have a general upward FM throughout the call ( Fig. 11B ). There is PFM throughout the call, which is directly proportional to the synchronic pulse-PAM, i.e. , each pulse has an up-downward FM ( Fig. 11F ). Additionally, another PFM is present within some pulses and it is directly proportional to the synchronic slight PAM within the pulses.