Molecular ecology of Round Island petrels

Round Island is a small islet off the north coast of Mauritius and is of international importance in conservation biology, with the removal of exotic species and habitat reconstruction underway. Our links with the Mauritius Wildlife Foundation have allowed us access to the island, to contribute to the ongoing conservation and biological research. Round Island Petrels were only distinguished in the 1940's, and this population is unique for several reasons: it is closed; it is on just one island; most of the birds are ringed and nearly all of the nest sites are known and marked.

The petrels on Round Island usually nest in the open, in groups (clusters), and extensive ringing data suggests that birds form long-term pair bonds. They also display a high degree of site fidelity despite frequently being close to vacant sites with hollows that are thought to have much higher hatching success. Part of the explanation for this spatial pattern of nests may involve attacks on eggs and young by conspecific intruders. Another puzzling aspect of their reproductive behaviour is that only a proportion of the population is breeding at any one time. We are using genetic markers (mtDNA and microsatellites), along with the ringing records and systematic observation, to evaluate the relatedness of group members and aggressors, and their contribution to attack and defence. Parentage analysis will also enable us to evaluate the mating system, and to investigate a  skew in reproductive success, which may be related to habitat saturation.
We are also conducting a survey of mitochondrial DNA (mtDNA) haplotypes present in the population, to distinguish and identify the species present and their relationships. In conjunction with microsatellite markers we will evaluate the extent of cross-breeding (hybridization) between these putative species, and the extent to which this leads to genetic mixing. This genetic groundwork will provide the fundamental information for evaluating the taxonomic and conservation status of these petrels, and for drafting guidelines for appropriate management.

Round Island petrel

Round Island