Synchronized calling in {\it Centrolenella granulosa\/} and {\it Smilisca sila\/} (Amphibia, Anura)

Date of Completion

January 1991

Keywords

Biology, Zoology

Degree

Ph.D.

Abstract

Males of a few anuran species call in bouts separated by relatively long periods of silence. This type of synchronized calling behavior was investigated in Smilisca sila and Centrolenella granulosa in Panama.^ The vocal repertoire of S. sila consists of: (1) advertisement calls, composed of an initial pulsed "squawk" note, usually followed by 0-5 secondary "squawk-rattling" notes, and (2) aggressive calls, consisting of single pulsed notes of variable duration. A male responds to a neighbor's call by giving an advertisement call within 2-279 ms and remaining silent for several seconds. Males overlap their calls with the chorus 69-100% of the time. Males tend to alternate their notes with those of their neighbors, although 13-56% of all notes partially overlapped. Response latencies are short, but some males delay their responses to avoid signal interference. Males increase the number of notes as the number of notes in stimulus calls increases.^ Centrolenella granulosa males give: (1) advertisement calls, composed of a pulsed primary note followed by 0-5 shorter pulsed secondary notes, and (2) aggressive calls, composed of a long pulsed primary note followed by 0-3 secondary notes. A male responds rapidly (within 816 ms) to a neighbor's call by giving an advertisement call and remaining silent for several seconds. Males overlap their advertisement calls with the chorus 92-100% of the time, and overlap 17-85% of all notes. Most note overlap is out-of-phase, which is known to degrade the temporal pattern encoded in the signal. Males showed some tendency to increase response latencies as stimulus duration increased. Males did not add notes to their calls in response to multi-note stimuli. Female choice does not appear to influence the degree of call overlap in C. granulosa, but call overlap does seem to reduce the ability of males to attract mates.^ The vocal behavior of both species is unusual in that males give only one call at a time, actively overlapping it with calls of their neighbors. However, they differ in that C. granulosa males overlap individual notes within calls, whereas S. sila males usually do not. ^

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