Advertisement Call Complexity in Northern Leopard Frogs, Rana pipiens

The advertisement call of Rana pipiens males may be the most complex of any temperate-zone anuran. To characterize call complexity, I analyzed acoustic properties and temporal patterning of male advertisement call notes. Calls included up to three note types (snores, grunts, and chuckles) and varied in complexity from one to 65 notes/call. Four common temporal patterns of notes in calls were observed, and transition probabilities of note pairs were nonrandom. Temperature influenced spectral and temporal properties of all note types; body size only influenced snore dominant frequency. Finally, I compared R. pipiens calls to other anurans possessing complex advertisement calls. Although the function of specific call notes has been documented in these other species, the function of call notes in R. pipiens remains unclear.