Ecology and Seasonal Habitat Use of Northern Bottlenose and Sowerby's Beaked Whales in the Azores

ABSTRACT Beaked whales are among the least known cetaceans, yet they are regularly observed in the Azores, a region recognized as a hotspot for deep‐diving species. In this study, we analyzed opportunistic sightings collected during 1492 whale‐watching trips, including 149 beaked whale encounters, of which 89 were Sowerby's ( Mesoplodon bidens ) and 31 northern bottlenose whales ( Hyperoodon ampullatus ). Our results reveal a clear seasonal pattern, with most sightings occurring in summer (92.7%), when habitat suitability reached its highest values. Group composition analyses consistently documented juveniles and calves, but the absence of neonates prevents firm conclusions about a possible breeding/calving ground. Foraging was the most frequently observed behavior, followed by socializing (including spy‐hopping and breaching), with short encounter durations (mean ~6 min) reflecting the constraints of opportunistic data collection. Responses to whale‐watching vessels were most often indifference (65%), but evasive reactions (21%) highlight the need for careful management of anthropogenic activities during periods of higher seasonal occurrence. Taken together, our findings suggest that the Azores represent a seasonally important habitat for beaked whales; we suggest that it is potentially linked to processes such as reproduction, molting, or reduced predator presence. Further research integrating effort‐corrected surveys, photo‐identification, unmaned aerial vehicles and satellite telemetry will be essential to clarify the ecological function of the Azores for these poorly known species.