Ecogeographical variation in the Southern Giant Petrel (Macronectes giganteus)

Southern Giant Petrels (Macronectes giganteus) exhibit significant ecogeographical variation across their range, from New Zealand to the Sub-Antarctic and Antarctic regions. Six distinct breeding provinces were identified, confirming two recognized subspecies: M. g. giganteus and M. g. solanderi. The latter is characterized by smaller body parts compared to the former. Morphological differences include variations in bill depth and tarsus length, with birds from Gough Island displaying the longest tarsi. Additionally, an east-to-west cline shows a gradual decrease in body size, consistent with Allen’s rule. While M. g. giganteus exhibits morphological polymorphism, M. g. solanderi shows less biometric variability, suggesting potential for taxonomic differentiation. This study underscores the need for further morphometric and genetic research to clarify the taxon's classification.

Salomon, M., & Voisin, J.-F. (2010). Ecogeographical variation in the Southern Giant Petrel (Macronectes giganteus). Canadian Journal of Zoology, 88(2), 195–203. https://doi.org/10.1139/z09-134