Field acoustic playback experiments were conducted with maleEleutherodactylus coqui andE. portoricensis. Periodic tone bursts of intensities similar to natural sounds in the habitat of the frogs were used to create sonic interference. The period between tone bursts, the ‘time window’, was varied in duration and in intensity relative to the tone burst.
Males of both species suppressed vocalizations during the stimulus tone bursts. The amount of suppression decreased as the tone burst was lengthened.
Males of bothE. coqui andE. portoricensis suppressed calling in response to tone bursts of 0.40 to 2.0 kHz, a range which encompasses the principal frequency components present in their vocalizations.
BothE. coqui andE. portoricensis initiated significantly (P<0.01) more calls within the time windows between stimulus tone bursts than would be expected by chance when the window duration was as short as 0.25 s and 0.10 s, respectively. These durations are approximately 10% of the spontaneous call repetition periods for each species.
E. coqui initiated significantly (P<0.01) more calls than would be expected by chance in tone-filled time ‘windows’ which were only 4 to 6 dB less intense than the tone bursts. This ability of intensity discrimination under sonically adverse natural field conditions indicates a level of performance in the same range as that of mammals.
The ability of frogs to call preferentially during very brief silent periods or during periods of slight intensity reductions is viewed as an adaptation for avoiding acoustic interference, and thus improves the efficiency of acoustic communication in an intense and complex sonic environment.
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- SPL :
sound pressure level
- PST :
post stimulus time
- TTL :
Bucher TL, Ryan MJ, Bartholomew GA (1982) Oxygen consumption during resting, calling and nest building in the frogPhysalaemus pustulosus. Physiol Zool 55:10–22
Bullock TH, Hamstra RH Jr, Scheich H (1972) The jamming avoidance response of high frequency electric fish II. Quantitative aspects, J Comp Physiol 77:23–48
Chocholle R (1943) Relation de la latence d'une sensation auditive différentielle avec l'amplitude d'une variation brusque d'intensité. CR Soc Biol (Paris) 137:751–752
Drewry GE (1970) The role of amphibians in the ecology of Puerto Rican rain forest. In: Puerto Rican Nuclear Center Rain Forest Project Annual Report 1970. Puerto Rico Nuclear Center, San Juan, pp 16–63
Ehret G, Capranica RR (1980) Masking patterns and filter characteristics of auditory nerve fibers in the green treefrog (Hyla cinerea). J Comp Physiol 141:1–12
Ehret G, Gerhardt HC (1980) Auditory masking and effects of noise on responses of the green treefrog (Hyla cinerea) to synthetic mating calls. J Comp Physiol 141:13–18
Gerhardt HC (1981) Mating call recognition in the green treefrog (Hyla cinerea): Importance of two frequency bands as a function of sound pressure level. J Comp Physiol 144:9–16
Jesteadt W, Wier CC, Green DM (1977) Intensity discrimination as a function of frequency and sensation level. J Acoust Soc Am 61:169–177
Lemon RE, Struger J (1980) Acoustic entrainment to randomly generated calls by the frog,Hyla crucifer. J Acoust Soc Am 67:2090–2095
Littlejohn MJ, Martin AA (1969) Acoustic interaction between two species of leptodactylid frogs. Anim Behav 17:785–791
Loftus-Hills JJ (1971) The neural basis underlying acoustic behavior of the frogPseudophryne semimarmorata (Anura: Leptodactylidae). Anim Behav 21:781–787
Loftus-Hills JJ (1974) Analysis of an acoustic pacemaker in Strecker's chorus frog,Pseudacris streckeri (Anura: Hylidae). J Comp Physiol 90:75–87
McGill WJ, Goldberg JP (1968) Pure tone intensity discrimination and energy detection. J Acoust Soc Am 44:576–581
Megela AL, Capranica RR (1981) Response patterns to tone bursts in peripheral auditory system of anurans. J Neurophysiol 46:465–478
Narins PM (1982) Effects of masking noise on evoked calling in the Puerto Rican coqui (Anura: Leptodactylidae). J Comp Physiol 147:439–446
Narins PM (1983) Divergence of acoustic communication systems of two sibling species of eleutherodactylid frogs. Copeia (in press)
Narins PM, Capranica RR (1976) Sexual differences in the auditory system of the treefrogEleutherodactylus coqui. Science 192:378–380
Narins PM, Capranica RR (1977) An automated technique for analysis of temporal features in animal vocalizations. Anim Behav 25:615–621
Narins PM, Capranica RR (1980) Neural adaptations for processing the two note call of the Puerto Rican treefrog,Eleutherodactylus coqui. Brain Behav Evol 17:48–66
Narins PM, Hurley DD (1982) The relationship between call intensity and function in the Puerto Rican coqui (Anura: Leptodactylidae). Herpetologica 38:287–295
Prosen CA, Moody DB, Stebbins WC, Hawkins JE Jr (1981) Auditory intensity discrimination after selective loss of cochlear outer hair cells. Science 212:1286–1287
Raab DH, Grossberg M (1965) Reaction time to changes in the intensity of white noise. J Exp Psychol 69:609–612
Rivero JA (1978) Los anfibios y reptiles de Puerto Rico. Univ Puerto Rico Editorial Universitaria, San Juan
Rose G, Capranica RR (1983) Temporal selectivity in the central auditory system of the leopard frog. Science 219:1087–1089
Watanabe A, Takeda K (1963) The change of discharge frequency by A.C. stimulus in a weak electric fish. J Exp Biol 40:57–66
Zelick RD, Narins PM (1982) Analysis of acoustically evoked call suppression behaviour in a neotropical treefrog. Anim Behav 30:728–733
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Zelick, R.D., Narins, P.M. Intensity discrimination and the precision of call timing in two species of neotropical treefrogs. J. Comp. Physiol. 153, 403–412 (1983). https://doi.org/10.1007/BF00612594
- Silent Period
- Repetition Period
- Tone Burst
- Acoustic Communication
- Playback Experiment