Abstract
Sperm whales depend on sound for nearly every part of their lives, from foraging to maintaining tight social relationships. One of their primary forms of social communication is through codas, a sequence of clicks used within and between stable matrilineal groups. Although codas have been studied in several regions, the vocal behavior of sperm whales in the Gulf of America remains poorly understood. This project analyzed acoustic recordings from three NOAA cruises (GUI 703, GU1801, and PC1805) to examine how coda types and inter-click interval (ICI) patterns varied across encounters. Codas were analyzed in Raven Lite and PAMGuard, and timing patterns were explored through statistical summaries, boxplots, dendrograms, PCA, and sequence raster plots. Across the three cruises, coda structure differed both within and among coda types. Regular and variable codas generally showed higher ICis and broader timing ranges, while creaks formed tight clusters with very short ICis. PC1805 contained the widest range of rare and longer-click variable codas, indicating either socially active groups or a greater diversity of whales. Low coda counts or the absence of certain types also provided insight into whale behavior, whether due to fewer whales in the area, limited time at the surface, or behavioral states where codas were not prioritized.
Overall, this study described clear patterns in how sperm whales in the Gulf of America used codas across different behavioral contexts and recording conditions. These findings highlight the value of passive acoustic monitoring for studying social behavior in a region where visual surveys are limited and provide baseline information for future behavioral and conservation work.