Notes: Information relevant to lice see under section 1.2 Background, page 24
Albatrosses and petrels (Order Procellariiformes) are renowned for the huge distances they can cover at sea, and since the advent of tracking technology their pelagic lifestyles are generally well studied. However, tropical species are under-represented in the literature, and may be particularly flexible in their behaviour since tropical oceans are oligotrophic and prey availability is often patchily distributed.
Round Island petrels breed in such an environment off the coast of Mauritius in the south-western Indian Ocean. Whilst originally identified as Trindade petrels (Pteromdroma arminjoniana), it has recently been revealed that this population is in fact a mixed, hybridizing population with at least two additional species, namely the Kermadec and Herald petrels (P. neglecta and P. heraldica). However, to date no research has been conducted on the colony-based at-sea distribution of these petrels, or how their mixed ancestry may influence their distribution at sea.
In this thesis I firstly explore the possibility that Round Island may not be the only point of contact between these species and find that migration and introgression between wide-ranging Pterodroma may be more common than previously thought.
I go on to develop a novel data cleaning method to enable the analysis of geolocation data from Round Island petrels, and use that data to describe for the first time their at- sea distribution and the extensive within-population variation in these patterns.
Finally, I use a combination of tracking and microsatellite genotype data to ultimately weigh the influence of individual genetic background and the wider seasonal environment on distribution variability around the breeding colony.
The Round Island petrel population is a stronghold where seabird populations globally are in decline. This thesis adds to the limited literature on ecology of tropical petrel species, and highlights the importance of considering behavioural and genetic diversity in future conservation plans.