Vocalizations and species limits in the North Atlantic clade of small shearwaters (Procellariiformes: Puffinus)

Abstract

Species limits in the North Atlantic clade of small shearwaters (Puffinus lherminieri lherminieri, P. l. baroli, and P. l. boydi) have been controversial. In this study, the aerial calls of P. l. boydi are described in detail and compared with those of P. l. baroli and P. l. lherminieri. Multivariate methods were used to test for differences in seven characteristics of aerial calls among the three taxonomic groups, in a sample of 135 individuals. There were differences between males and females in five of the seven call elements studied and differences in all seven call elements among the three taxonomic groups. Discriminant function analysis provided a high degree of discrimination, with 91%–100% of the calls being assigned to the correct taxon. The overall level of acoustic differentiation between P. l. baroli and P. l. boydi was similar to that between P. l. baroli and P. l. lherminieri and twice as high as that of P. l. boydi and P. l. lherminieri. These acoustic data, in combination with previously reported patterns of morphometric and molecular divergence, support the recognition of three North Atlantic species: P. lherminieri, P. baroli, and P. boydi. This study underscores that patterns of acoustic variation provide a useful source of information for taxonomic studies of procellariiform seabirds.