Bretagnolle (1989) described three kinds of vocalizations used by Wilson's Storm-Petrel.
Most vocalizations are used on the breeding grounds. The most common call is a "grating call", utilized by both sexes and usually given from within the burrow, though males may use it from a territorial perch or rarely in the air. This call has been reported very occasionally at sea as well (Murphy 1936). Grating calls may be long, consisting of three to six syllables, or long ones of twelve or more syllables. Variation within individuals may be recognizable, but not between populations. Robb et al. (2008) suggest it may serve for aggressive purposes.
"Chatter calls" are also used by males on territory. They have more syllables than grating calls and are uttered at a faster pace. Chatter calls usually are performed from the ground and outside the burrow, though occasionally they are uttered from within the burrow, when with a mate. In this situation, chatter calls are used in tandem with grating calls.
Chicks give a "peeping call", which likely is used as an appeasement contact call. Adults use a similar vocalization as a form of distress or agitation call which may be used in the air or on the ground. Murphy (1936) described this vocalization as "sounds not unlike those made by a nest ful of young chickadees when the parent arrives with food."
There are significant differences between the vocalizations of the subspecies oceanicus, from Kerguelen Island, and those of subspecies exasperatus, from South Georgia and the South Sandwich Islands (Jouanin and Mougin 1979, Bretagnolle 1989, Brooke 2004).
Additional audio recordings of vocalizations of Wilson's Storm-Petrel can be heard at Macaulay Library.