Blainville’s beaked whale
(Mesoplodon densirostris)

Blainville’s beaked whale is the most frequently sighted beaked whale in Madeira and occurs regularly throughout the year. Some individuals show evidence of repeated use of the area both within the same year and across multiple years, indicating that these waters are an important habitat for this species (Dinis et al., 2017; Alves et al., 2018). Its habitat is also strongly associated with steep slopes, major canyons, and warm waters, with higher suitability in summer and early autumn (Fernandez et al., 2021).

Like sperm whales, Blainville’s beaked whales are deep-diving predators that use a similar general acoustic hunting pattern: long series of echolocation clicks during prey search, followed by rapid terminal buzzes during prey capture. However, the signals themselves differ in structure, as Blainville’s beaked whales produce high frequency-modulated clicks during deep foraging dives, typically in long series of regularly spaced clicks centred around 30–34 kHz (Baumann-Pickering et al., 2018). Search clicks are emitted mainly at depth during foraging, whereas buzz clicks are shorter and produced at much higher repetition rates as the animal closes in on prey (Johnson et al., 2006). In addition to these foraging sounds, a small number of whistle and burst-pulse sounds have been reported near surface groups, suggesting that the species is also capable of producing short communicative signals, although these appear to be far less conspicuous and much less frequently recorded than the deep-foraging biosonar signals (Rankin and Barlow, 2007; Aguilar de Soto et al., 2012). Because most of the species’ acoustic activity is produced during deep foraging rather than surface behaviour, acoustic presence is expected to reflect periods of deep feeding activity.