Brijonnay Madrigal – bcm2@hawaii.edu
Instagram: @brijonnay
Marine Mammal Research Program
University of Hawaiʻi at Mānoa
46-007 Lilipuna Rd
Kaneohe, HI 96744
United States
Marine Mammal Research Program @mmrp_uh
Popular version of 5aAB – Acoustic behavior of endangered false killer whales (Pseudorca crassidens) using biologging devices in Hawaiʻi
Presented at the 188th ASA Meeting
Read the abstract at https://eppro01.ativ.me/appinfo.php?page=IntHtml&project=ASAICA25&id=3864165&server=eppro01.ativ.me
–The research described in this Acoustics Lay Language Paper may not have yet been peer reviewed–
Photo Credit: Grace Olson (Pacific Whale Foundation)
How do scientists better understand the communication of individual animals when we don’t know who is speaking and what they are doing underwater? For cetaceans (whales/dolphins/porpoises), passive acoustic monitoring is an important approach to study these animals that spend most of their time underwater and rely on acoustic signaling to communicate. The use of acoustic biologging tags has enabled the collection of high-resolution data to study acoustic behavior of top predators. The Main Hawaiian Islands (MHI) insular population of false killer whales (Pseudorca crassidens) is the most endangered toothed whale population in Hawaiʻi under the Endangered Species Act. Despite ongoing management efforts to address threats, the population has continued to decline to a current population size of less than 150 individuals. Therefore, it is crucial to understand the behavior of this population to better inform conservation measures critical for the protection of this species. Our understanding of the social context of individual false killer whales has generally been limited, until now.
The goal of this study was to use data recorded from non-invasive archival , suction-cup tags, to describe the acoustic behavior of MHI insular false killer whales to better understand the behavioral context of social signals. Our objectives were to (1) classify and characterize the repertoire of individual false killer whales; (2) describe nonlinear features observed in calls that enhance communication between individuals; and (3) analyze the relationship between social sound production and diving behavior. These findings can help us evaluate social context on a small scale and provide foundational information to determine the potential function of these signals.
Our results show that MHI insular false killer whales have a more diverse repertoire than previously described. Some call types are shared between individuals, and some are unique to individuals. We identified predominate call types that are repeated or favored by specific individuals and call rates vary by individual across dive states (for example – descent, ascent) (Figure 1). Most calls are biphonic, where the animals produce a call and clicks simultaneously (Audio 1). Although clicks are commonly used for echolocation to navigate and locate prey, the clicks produced by these animals occur with calls at the same time in distinct patterns, so they likely function in communication and encode additional information for individuals. This study provides invaluable insights into this species’ social behavior and by intercepting the coconut wireless of Hawaiʻi false killer whales using tag technology, our findings can inform management strategies necessary to advance conservation efforts of this top predator to the Hawaiʻi ecosystem.
Figure 1: A spectrogram of three predominate call types produced by one tagged false killer whale from the Main Hawaiian Islands insular population. Calls are biphonic which means a call and clicks are produced simultaneously, as indicated by the arrows in the first panel. A spectrogram is a visual representation of sound with time on the x-axis, frequency (or pitch) on the y-axis, and color representing the relative amplitude (loudness) of the sound.
Image credit: Grace Olson (Pacific Whale Foundation)
Customized animal tracking solutions (CATS) tags audio recording of calls produced by a tagged MHI insular false killer whale.