Assessing Northern Gulf of Mexico Sperm Whale’s (Physeter macrocephalus) time budget using passive acoustic monitoring

Abstract

A time budget empirically measures species-specific behavior regarding the time periods spent engaging in a certain behavior. Sperm whales emit phonations categorized as either foraging or socializing, making it straightforward when creating their time budget based on acoustic observations alone. Understanding regional time budgets can help assessing habitat uses, prey availability, as well as identifying short and long-term trends across the population. Furthermore, sperm whales exhibit both high sexual dimorphism as well as sexually regulated group structures. Individualized multi-pulse echolocation click structure allows total body length as well as sex to be estimated. Apart from a case study conducted by McDonald et al., 2017, a long-term time budgets for sperm whales have not been investigated in the Northern Gulf of Mexico (NGoM). The analysis of multi-year archival acoustic data from the NGoM using a sperm whale click detector as well as CABLE software [Beslin et al., JASA (2018)] is presented to infer sperm whale’s time budget and group structures. [Data acquisition for this research was made possible in part by grants from The Gulf of Mexico Research Initiative and BOEM.]