“…A unique FM pulse type was first recorded near Cross Seamount in the Pacific Ocean south of Hawaii, with a linear frequency upsweep from 35 to 100 kHz, duration of 932 μs, and mean IPI of 0.14 s (McDonald et al 2009). This FM pulse type, called the BWC signal (Baumann‐Pickering et al, 2013), has been recorded in a number of tropical locations throughout the central and western Pacific Ocean (Baumann‐Pickering et al, 2014) and elsewhere in Hawaii (Manzano‐Roth et al, 2023), the Mariana Archipelago (McCullough et al, 2021b), and off Baja California, Mexico (Simonis et al, 2018), but has never been definitively linked to a known species. Its acoustic features are distinctive from other beaked whale signals due to the pulse's longer duration, shorter IPI, and extremely wide bandwidth.…”