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.Abstract

Advertisement calls of Rana pipiens. (A) Sonogram of three successive advertisement calls, where a call is a group of notes in close temporal proximity (internote intervals ≤ 5 seconds). (B) Expanded view of call 2, highlighting the individual snore (S), grunt (G), and chuckle (C) notes comprising the call. (C) Oscillogram of call 2. Subscripts indicate the number of subnotes per chuckle

Kinematic representation of transition probabilities between note pairs in advertisement calls of Rana pipiens. The diagram is based on a total of 7857 note pairs, averaging values from 39 males. Arrow thickness is approximately proportional to first-order transition probabilities (see Table 3), with probabilities less than 10% represented by dotted lines. All arrows leading away from each note sum to 100%
Contributor Notes
Department of Biological Sciences, Purdue University, 915 West State Street, West Lafayette, Indiana 47907–2054. klarson@bilbo.bio.purdue.edu