Roars, Rumbles, and Resonance: A Systematic Review and Meta-Analysis of Crocodylian Acoustic Signals

Area of Science:

• Bioacoustics
• Herpetology
• Animal Communication

Background:

• Crocodylians exhibit complex acoustic signaling for various social behaviors.
• Existing research on crocodylian vocalizations is limited and lacks standardized methodologies and terminology.
• This inconsistency hinders cross-species comparisons and a comprehensive understanding of their communication systems.

Purpose of the Study:

• To systematically review and standardize descriptions, measurements, and terminology of crocodylian acoustic signals.
• To establish a consistent foundation for future bioacoustic research on crocodylians.
• To identify data gaps and propose future research directions.

Main Methods:

• Systematic literature review of 22 publications on crocodylian acoustic signaling.
• Compilation of 623 acoustic signaling observations and 53 distinct parameters.
• Synthesis of acoustic parameters into comparable values and units, creation of a standardized ethogram and glossary.

Main Results:

• The American alligator (Alligator mississippiensis) was the most studied species; distress calls were the most common signal.
• Significant variation was found in measured acoustic parameters across studies.
• A centralized database, standardized ethogram, and glossary were created, highlighting data gaps, especially in underwater acoustics.

Conclusions:

• Standardization of terminology and methods is crucial for advancing crocodylian bioacoustics.
• Future research should focus on a broader range of spontaneously produced signals and underrepresented parameters.
• Reanalysis of existing data and collaborative efforts can enhance insights for conservation and management, including passive acoustic monitoring.