Selectivity of evoked vocal responses in the time domain by frogs of the genus Batrachyla

The leptodactylid frogs Batrachyla taeniata, B. antartandica and B. leptopus in southern Chile produce advertisement calls composed of short pulses, repeated in species-specific patterns. Batrachyla leptopus has a call with a complex structure relative to the other species, with pulses grouped in notes. Male frogs were presented with synthetic imitations of conspecific advertisement calls and variants for which different temporal components were varied systematically. Males of B. taeniata responded with fewer calls to synthetic stimuli having a low pulse rate (12.5 pulses/sec) relative to a standard stimulus imitating the natural advertisement call (50 pulses/sec). In contrast, males of B. antartandiea gave fewer responses to stimuli having a high pulse rate (8 pulses/sec) relative to the standard call of this species (2 pulses/sec). Batrachyla taeniata save weaker responses to continuous tones of the same duration as the standard call (500 msec), and B. antartandica also decreased si

Amplification and spectral shifts of vocalizations inside burrows of the frog Eupsophus calcaratus (Leptodactylidae)

A variety of animals that communicate by sound emit signals from sites favoring their propagation, thereby increasing the range over which these sounds convey information. A different significance of calling sites has been reported for burrowing frogs Eupsophus emiliopugini from southern Chile: the cavities from which these frogs vocalize amplify conspecific vocalizations generated externally, thus providing a means to enhance the reception of neighbor's vocalizations in chorusing aggregations. In the current study the amplification of vocalizations of a related species, E. calcaratus, is investigated, to explore the extent of sound enhancement reported previously. Advertisement calls broadcast through a loudspeaker placed in the vicinity of a burrow, monitored with small microphones, are amplified by up to 18 dB inside cavities relative to outside. The fundamental resonant frequency of burrows, measured with broadcast noise and pure tones, ranges from 842 to 1836 Hz and is significan

Ethanol metabolism by rat heart homogenates

Supernatant of rat heart homogenates obtained by centrifugation at 700 × g for 10 min, incubated in the presence of ethanol (25 and 50 mM) and glucose (10 mM) were found to oxidize ethanol to acetaldehyde (AcH) in such a way that after 60 minutes of incubation around 5 to 8 nmole per mg of protein were recovered. The addition of glucose oxidase (5 μg/ml), a known hydrogen peroxide generator system, to the incubation medium, significantly increased by about ten times the recovery of acetaldehyde. On the opposite, the presence of 3-amino-1,2,4-triazole (10 to 40 mM), a known catalase inhibitor, induced a concentration dependent reduction of the amount of AcH recovered during incubation even in presence of glucose oxidase. These findings support the idea that a catalase mediated oxidation of ethanol is acting in rat heart homogenates. AcH content of a medium in which rat heart homogenates were incubated in the presence of NAD (0.7 mM) decreased by 87% at 60 minutes. This effect was not o

Vocal Strategies in Confronting Interfering Sounds by a Frog from the Southern Temperate Forest, Batrachyla antartandica

Animals are communicating by sound face interference from biotic and abiotic sources. Contrasting strategies have been reported in different taxa in the presence of prolonged noises, but in particular, interactions among acoustically active species have been studied to a very limited extent. In addition, reactions of a single species to interferences having contrasting structural patterns have not been explored systematically. The vocal responses of 16 male frogs Batrachyla antartandica from the temperate austral forest in Chile were tested with conspecific calls and with the calls of two sympatric species: B. taeniata and B. leptopus, broadcast at amplitudes of 73, 79, 85, 91, and 97dB peak sound pressure level (SPL). Also, the vocal activity of the subjects during exposure to a 3-min continuous broadband noise presented at 67dB root mean square (RMS) SPL was monitored. The subjects gave significantly higher responses to the conspecific relative to the heterospecific calls but increa

Independence of evoked vocal responses from stimulus direction in burrowing frogs Eupsophus (Leptodactylidae)

Localization of a sound source is important for animals in mating contexts: females generally orient towards signalling males, and males can estimate the position and quality of potential rivals. In anurans, the effect of sound direction on evoked vocal responses has been studied in males of Rana catesbeiana, which alter their vocal responses depending on the location of the stimulus. The current study explored the effects of sound direction in Eupsophus calcaratus, a frog that calls from inside burrows having resonance that would hinder the localization of incoming sounds. The vocal responses of 11 males to synthetic imitations of the conspecific advertisement call broadcast from loudspeakers positioned in front, to the right and left from the burrow openings were similar in terms of call rate, duration and latency. The invariance of the vocal responses indicates that for burrowing male frogs engaged in chorusing behaviour, the specific location of an opponent does not alter the pers

Heterospecific Vocal Interactions in a Frog from the Southern Temperate Forest, Batrachyla taeniata

Animals using sound communication employ different strategies to overcome interferences from biotic and abiotic sources. However, interactions among acoustically active species have been studied to a very limited extent. The evoked vocal responses of 20 male frogs Batrachyla taeniata from the temperate austral forest in Chile were tested with conspecific calls and with the calls of two sympatric species: B. antartandica and B. leptopus, broadcast at amplitudes of 73, 79, 85, 91 and 97 dB peak SPL. The subjects responded actively to the conspecific call, but only responded weakly to the call of B. leptopus at the highest intensity. The preferential responses to conspecific calls could contribute to the typical segregation in monospecific choruses observed in areas where these frogs breed in sympatry. © 2010 Blackwell Verlag GmbH

Extended amplification of acoustic signals by amphibian burrows

© 2016, Springer-Verlag Berlin Heidelberg.Animals relying on acoustic signals for communication must cope with the constraints imposed by the environment for sound propagation. A resource to improve signal broadcast is the use of structures that favor the emission or the reception of sounds. We conducted playback experiments to assess the effect of the burrows occupied by the frogs Eupsophus emiliopugini and E. calcaratus on the amplitude of outgoing vocalizations. In addition, we evaluated the influence of these cavities on the reception of externally generated sounds potentially interfering with conspecific communication, namely, the vocalizations emitted by four syntopic species of anurans (E. emiliopugini, E. calcaratus, Batrachyla antartandica, and Pleurodema thaul) and the nocturnal owls Strix rufipes and Glaucidium nanum. Eupsophus advertisement calls emitted from within the burrows experienced average amplitude gains of 3–6 dB at 100 cm from the burrow openings. Likewise, the

Testosterone levels and evoked vocal responses in a natural population of the frog Batrachyla taeniata

Relationships between testosterone plasma levels and evoked vocal responses of males of the leptodactylid frog Batrachyla taeniata from southern Chile were studied. Evoked vocal responses were elicited in the field with playbacks of a synthetic imitation of the conspecific advertisement call and variants of this signal for which different temporal parameters were modified. Testosterone plasma levels were measured with radioimmunoassay in blood samples obtained from the experimental subjects immediately after the playback experiments and from nonstimulated males. Testosterone levels between groups did not differ significantly. A significant correlation between testosterone concentration and number of calls given in response to the synthetic advertisement call was found. Testosterone levels were also significantly correlated with the total number of calls given by the experimental subjects in response to the complete series of stimuli. Other measures of evoked vocal responses, i.e., num

Influence of burrow acoustics on sound reception by frogs Eupsophus (Leptodactylidae)

The effect of burrow acoustics on the reception of sounds by a leptodactylid frog, Eupsophus emiliopugini, from Southern Chile was investigated. Burrows occupied by E. emiliopugini males amplified vocalizations produced by conspecific individuals calling nearby and conspecific calls played back through a speaker positioned in the vicinity of the burrow by 5.2 dB (N = 4) and 4.3 dB (N =5) on average, respectively. The spectral contents of calls recorded from inside burrows matched the resonant frequencies of the cavities measured with pure tones. Playback calls of a sympatric species, Batrachyla antartandica, which have spectra that do not overlap E. emiliopugini calls, were not amplified inside burrows to the same extent. Amplification of conspecific calls inside burrows may influence vocal interactions in chorusing assemblages of E. emiliopugini. © 1996 The Association for the Study of Animal Behaviour