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Playback experiments indicate absence of vocal recognition among temporally and geographically separated populations of Madeiran Storm‐petrels Oceanodroma castro
Author(s) -
BOLTON MARK
Publication year - 2007
Publication title -
ibis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.933
H-Index - 80
eISSN - 1474-919X
pISSN - 0019-1019
DOI - 10.1111/j.1474-919x.2006.00624.x
Subject(s) - sympatric speciation , biology , seasonal breeder , zoology , ecology , sympatry
A number of lines of evidence suggest that temporally segregated sympatric populations of Madeiran Storm‐petrels Oceanodroma castro breeding in the Azores are reproductively isolated and morphologically and genetically distinct from each other. Within the Galapagos Islands, similar sympatric populations may also be isolated from each other, as individuals are not known to switch breeding seasons. The taxonomic relationships among populations of this species that are seasonally and spatially separated are unclear and in need of revision. In this study, playback experiments were used to determine the level of vocal response among prospecting Madeiran Storm‐petrels at colonies in the Azores, Galapagos and Cape Verde islands to recordings from different populations. Vocalizations of all populations studied here differ in their structural characteristics and in all but one case prospecting Storm‐petrels showed far greater response to playback of burrow calls from their own colony type than to calls recorded at other seasonally or geographically distinct colonies. Additionally, the level of response to foreign colony types was no different to playback of vocalizations of an unrelated control species present at the same location. Although not all combinations of geographical and seasonal populations could be examined, the finding that prospecting hot‐season (breeding April–August) Storm‐petrels in the Azores did not differ in their response level to playback from Azores cool‐season (breeding August–March) storm‐petrels and Cory's Shearwaters Calonectris diomedea is of particular significance and suggests the existence of a pre‐mating isolation mechanism that would prevent interbreeding between these two sympatric populations. Furthermore, Azores hot‐season Storm‐petrels showed a similar absence of response to playback from Galapagos dry‐season (May–July) populations, indicating that they are also taxonomically distant from this group. Madeiran Storm‐petrels in the Cape Verde islands showed a low response rate to Azores hot‐season vocalizations, which did not differ from the response to unrelated controls. These data provide further evidence that the hot‐season Azores population represents a distinct taxon that is reproductively isolated from the sympatrically breeding cool‐season population, as well as from more distant populations in the Cape Verde and Galapagos islands.