Authors who wrote about Bermuda Petrel in the early days of European exploration and colonization of the New World used much poetic license, but many accounts point to an abundant, highly vocal, and very confiding bird—and one easily captured. Little was published about the species after 1620 and before the species' rediscovery in 1951, but the few who did write about Bermuda Petrel (e.g., Lefroy 1877, Verrill 1902, Bent 1922) had neither type specimen nor careful descriptions of plumage, voice, or behavior.
At sea, normally detected in flight; travels by sinusoidal arcing flight typical of small gadfly petrels, particularly during brisk winds (> 10 kts). Not attracted to ships. Presumably feeds by seizing prey at or just beneath the surface, as do other species of gadfly petrels, though direct observation of foraging Bermuda Petrels has not been reported. When not feeding, foraging, or flying, birds often rest on water; on rare occasions, individuals have been seen resting with other small gadfly petrel species. Birds waiting offshore of breeding islands occasionally gather in small rafts (2-6 individuals); these are thought to be nonbreeding subadults. Adults come to nest burrows only under the cover of darkness; subadults also return to breeding islets during hours of darkness, often vocalizing and practicing courtship flights.
Courtship in adults similar to other gadfly petrels: male and female duet in flight, calling (often antiphonally) while one pursues the other closely. Typically the male selects and prepares the nest site and entices female to inspect the site with him. Both adults spend most of December at sea, the female foraging heavily in preparation for egg-laying, which usually occurs in January.
Behavior at nest widely observed through public "nest-cams," broadcast via internet, and also by conservation officer and staff through tops of artificial burrows. Pair engages in some allopreening when both are at the nest. Female is fed by male when preparing to lay egg; both parents forage at sea to provide food for chick, which fledges by May or early June. Fledgling remains on its own for the last month or so, acquiring juvenile plumage (very similar to adults) and shedding natal down; older fledglings frequently sit at burrow entrance at darkness, appearing to observe the sky for long periods, and exercising wings. As in other gadfly petrels and other small tubenoses, fledgling departs burrow by itself.