Extent and variation of sound enhancement inside burrows of the frog Eupsophus emiliopugini (Leptodactylidae)

Variation of the amplification effect of burrows of the leptodactylid frog Eupsophus emiliopugini on conspecific calls generated externally was invest igated. Advertisement calls broadcast through a loudspeaker placed in the v icinity of a burrow were monitored with small microphones positioned inside and outside the cavity. For 150 presentations of calls of 15 individuals i n 12 burrows, 134 were amplified and 16 were attenuated (range -6-13 dB). T he fundamental resonant frequency of burrows, measured with broadcast noise and pure tones, averaged 814 Hz (range 302-1361 Hz) and covaried with burr ow length. The dominant frequency of the calls of burrow occupants (average 1062 Hz, range 636-1459 Hz) was not correlated with the fundamental resona nt frequency of these cavities. In burrows with low resonant frequencies, e xternally broadcast calls with high dominant frequencies were attenuated, o r amplified to a lower extent than calls with lower dominant frequencies. T he dominant frequencies of the calls experienced shifts towards the burrows ' fundamental resonant frequencies. The amplification of calls inside burro ws of E. emiliopugini exhibits manifest variability, with considerable pote ntial for facilitating acoustic interactions in this species.