Not really known. Chicks give a soft “peeping,” known as Rhythmic Call in Leach's Storm-Petrel (Oceanodroma leucorhoa; 3). Adults and chicks sometimes give a Screech or Squawk, if disturbed or handled (1).
Vocal Array; Repertoire and Delivery of Songs
At least two distinct vocalizations are given by adults. The one most frequently issued while in the burrow or sometimes on the ground near the burrow is an extended twitter, chattering, or trill—Burrow Call (2) or Purr Call, as in other storm-petrel species (3; Figure 4A). Consists of a continuous series of rapid chirps broken abruptly every 10–12 s by a louder “wheezier” portion as the bird takes a breath. After each breath, chirps resume softly but increase in volume rapidly (10). Call first described by D. R. Dickey and A. van Rossem (A. B. Howell in 73), who likened the sound to the song of the Wrentit (Chamaea fasciata). Crossin (30) also reported this vocalization from his visits to Islas Coronado in 1968.
The Flight Call (Chatter Call of Huntington et al. ) is common among storm-petrels in flight at night over the colony (Figure 4B). Occasionally answered by individuals (which may be mates) calling from nest. This is the song or territorial call given in the vicinity of (mostly above) the nest (see description of likely context for closely related Ashy Storm-Petrel in 2) given in response to other calling individuals. A weird, raspy shriek, not at all musical. A. B. Howell (in 73) reported, “This [call] I am unable to describe, except in that it consists of four notes.” Raspy nature similar to analogous call of Least Storm-Petrel and Ashy Storm-Petrel (O. homochroa) (cf. 2; DGA), but fuller and more emphatic. Much harsher than Leach's, which is close to being melodious (cf. sonograms in Ainley , Huntington et al. [ 3]). Howell and Webb (10) attest to its shrieky quality, describing it as “kreeih kreehr kree-kree-kree-kreehr, or kriih, krri, krri, ki-ki-kihr.”
Early descriptions of sounds were wrong. Palmer (18) described the Flight/Chatter Call as “puck-a-ree, puck-puckaroo,” quoting Anthony (71), who apparently described, without knowing, the Flight/Chatter Call of Leach's (Socorro) Storm-Petrel, as “tuc-a-ree, tuc-tuc-a-roo,” heard in an area where Black Storm-Petrels also nested on Islas Coronado. Murphy (8) and Crossin (30), too, apparently made reference to this same rendition of the call, without specifically hearing it themselves. Anyone who has heard this call of Black Storm-Petrel specifically from known individuals could not refer to their raspy shrieks in this way. Indeed, this is a better description of the calls of Leach's Storm-Petrel (75).
It is not known if these calls in this species exhibit sexual or geographic variation, but sexual variation in the Flight/Chatter Call is likely given such variation exists in other petrels (76, 74, 3).
Does not call at sea. Calls given just during nesting season, especially during pair-formation period. Vocalizations heard rarely during chick-provisioning period.
As calling occurs only at colonies, and the species is active on land only at night, calls are largely restricted to the hours of darkness, especially soon after arrival. Rarely, calls can be heard during the day, especially in the case of Burrow/Purr Call, at times when both mates remain together.
Places of Vocalizing
Assuming similarity to Ashy Storm-Petrel (cf. 2), Flight/Chatter Call given each time the bird circles above nesting cavity or chases intruders away. Burrow/Purr Call given only from nest cavity or on ground near nest.
Social Context and Presumed Functions
Prospecting nonbreeders most likely to give Flight/Chatter Call, as this is the “song,” or territorial announcement. Burrow/Purr Call given by mated birds in or near burrow, perhaps as a part of pair formation or recognition.