The vocal repertoires of Grey, White-chinned. Parkinson’s and Westland Petrels are compared with the aid of sonagrams. All species have some very loud calls built from short, staccato notes, often given at very high rates to produce rattles, cackles and brays. These appear to advertise the bird’s availability as a partner and/or possession of a territory, but some also seem to serve as threats. Other calls composed of longer notes are produced both when breathing in and when breathing out – as with Puffinus and Calonectris shearwaters. The recorded repertoire of the Grey Petrel is the smallest, that of the Westland Petrel the most extensive. There are indications that in some species there are sexual differences in their calls, but experimental verification is needed to confirm this.