At-sea behavioural ecology of the endangered MacGillivray’s prion from Saint Paul Island: combining tracking and stable

[Michael Szabo]

These 2 maps show the at-sea distribution of 7 adult MacGillivray's Prions from St Paul Island. Of the 7 individuals, 4 spent the 'inter-breeding' period in waters between SE Australia and SW New Zealand. The inter-breeding period is roughly March–September, and the main moult period is March–May.

[Michael Szabo]

Here are two comparison photos taken by Rob Morris and posted to Facebook of a Salvin's Prion (left) and a potential MacGillivray's Prion seen on an Eaglehawk Neck pelagic trip 2nd July. Note the black on the top of the bill.

[Michael Szabo]

Independent evolution of intermediate bill widths in a seabird clade

Masello, J.F., Ryan, P.G., Shepherd, L.D. et al. Mol Genet Genomics 297, 183–198 (2022).

Abstract: Interspecific introgression can occur between species that evolve rapidly within an adaptive radiation. Pachyptila petrels differ in bill size and are characterised by incomplete reproductive isolation, leading to interspecific gene flow. Salvin’s prion (Pachyptila salvini), whose bill width is intermediate between broad-billed (P. vittata) and Antarctic (P. desolata) prions, evolved through homoploid hybrid speciation. MacGillivray’s prion (P. macgillivrayi), known from a single population on St Paul (Indian Ocean), has a bill width intermediate between salvini and vittata and could also be the product of interspecies introgression or hybrid speciation. Recently, another prion population phenotypically similar to macgillivrayi was discovered on Gough (Atlantic Ocean), where it breeds 3 months later than vittata. The similarity in bill width between the medium-billed birds on Gough and macgillivrayi suggest that they could be closely related. In this study, we used genetic and morphological data to infer the phylogenetic position and evolutionary history of P. macgillivrayi and the Gough medium-billed prion relative other Pachyptila taxa, to determine whether species with medium bill widths evolved through common ancestry or convergence. We found that Gough medium-billed prions belong to the same evolutionary lineage as macgillivrayi, representing a new population of MacGillivray’s prion that originated through a colonisation event from St Paul. We show that macgillivrayi’s medium bill width evolved through divergence (genetic drift) and independently from that of salvini, which evolved through hybridisation (gene flow). This represents the independent convergence towards a similarly medium-billed phenotype. The newly discovered MacGillivray’s prion population on Gough is of utmost conservation relevance, as the relict macgillivrayi population in the Indian Ocean is very small.


https://link.springer.com/article/10.10 ... 21-01845-3

https://doi.org/10.1007/s00438-021-01845-3

[Steve Wood]

Some great data showing a potential” Hot spot” off Stewart island for Indian Ocean Prion’s.
This info, I believe, also adds wait to our recent sighting of Salvin’s Prion seen in that Zone.

Looks like a return trip is on the board.