Identifying behavioral states and habitat use of acoustically tracked humpback whales in Hawaii

Although humpback whales have been well‐studied on their Hawaiian breeding grounds, it is difficult to track individual animals over long distances without tags, particularly when they move offshore. Here, singing humpback whales were localized in three dimensions on the Pacific Missile Range Facility off Kauai, Hawaii, located between 20 km and 80 km offshore, from January 2011 through June 2014. Detailed behavioral analyses were conducted on the resulting tracks. One hundred and eight individual tracks were identified and metrics of these tracks were examined. Using these metrics, the tracks were classified into four behavior categories, described herein as Directed Travel, Repeated Stationary Dives, Mill, and tracks with Combinations of behavioral states. Some diel and seasonal patterns were identified, with Mill tracks occurring more at night than the other behaviors, Repeated Stationary Dive tracks occurring more during the day, and Directed Travel occurring only at the start and end of the breeding season. These results provide detailed insights into the movement of singing humpback whales, particularly in offshore waters where they may be migrating into or out of breeding grounds. This also contributes valuable information on the baseline behavior of humpback whales on a US Navy training range.