Bryde’s whale
(Balaenoptera edeni)

Bryde’s whale is the most frequently sighted baleen whale in Madeira and one of the most frequently sighted cetaceans overall. Its occurrence tends to peak in summer and autumn, and habitat models link it to warm waters and relatively low chlorophyll conditions (Alves et al., 2018; Fernandez et al., 2021). Marked interannual variability in habitat suitability suggests that Madeira may be used seasonally within a broader distributional range, rather than being occupied at similar levels every year, and that occurrence may also be influenced by broader circulation patterns (Fernandez et al., 2021; Steiner et al., 2008). More recent photo-identification work shows that at least some individuals show both site fidelity to the archipelago and connectivity with the Canaries, highlighting Madeira’s importance within a broader Macaronesian range (Ferreira et al., 2021).

Bryde’s whales produce a diverse but predominantly low-frequency acoustic repertoire, including tonal calls, frequency-modulated calls, pulsed moans, and discrete pulse series (Oleson et al., 2003; Heimlich et al., 2005; Širović et al., 2014). Many call types have dominant low-frequency components below 60–80 Hz, often lasting less than 3 s, including short alternating tonal phrases with tones around 29 or 37 Hz and downswept components around 25–16 Hz (Heimlich et al., 2005). Other call types occupy a somewhat higher band, particularly the Be9 downswept pulsed call, which has energy roughly in the 80–140 Hz range and lasts less than 1 s per unit, while other described calls include signals near 44 Hz with 2–4 harmonics (Oleson et al., 2003; Širović et al., 2014). Even higher frequency signals have been reported from a captive juvenile, including a growl-like pulsed moan at ~200–900 Hz and short pulse sequences with most energy between 400 and 610 Hz, showing that the broader reported repertoire can extend to nearly 950 Hz (Edds et al., 1993; Širović et al., 2014). Unlike the long, highly stereotyped songs of blue or fin whales, Bryde’s whale sounds are generally produced as short discrete calls, short repeated series, rather than extended song bouts (Oleson et al., 2003; Heimlich et al., 2005).