Morphology of the recently re-classified Tasman Masked Booby Sula dactylatra tasmani breeding on the Kermadec Islands

Stefanie M.H. Ismar, Karen Baird, Selina Patel, Craig D. Millar, Mark E. Hauber

Research output: Contribution to journalArticlepeer-review


Once thought to be extinct, the Tasman Booby Sula tasmani has recently been re-classified as a subspecies of the Masked Booby S. dactylatra on the basis of genetic data. This re-classification raises the issue of whether this novel clade has a distinct morphology. Morphological differences in size, as well as coloration of integuments, bill and iris have been found in other subspecies of the Masked Booby but have not yet been reported for live Kermadec Islands breeding individuals. Museum specimens from this breeding location have been separated from other Pacific breeding subspecies by their longer wings. We sampled a total of 21 individuals from North Meyer Islet, Kermadec Group, New Zealand, and applied molecular sexing to obtain sex-specific morphometric measurements. We matched dimorphism in vocalization with genetic sexing results and photographic documentation of human-assessed bill, foot and eye coloration. While culmen measurements were consistent with reports from museum specimens, wing chords from living specimens of Tasman Masked Boobies were 3% and 4% larger in males and females, respectively. Females had larger culmens and wings than males, consistent with the low extent of sexual dimorphism reported from museum skins. Adult Tasman Masked Boobies had yellow to buff-yellow feet, while fledglings, as in most sulids, had grey to greyish-yellow feet. Our findings confirm the distinctively long wing and particular iris coloration previously reported for the taxon and provide the first description of integument coloration of live specimens. This study highlights the importance of including in situ assessment in taxon descriptions.

Original languageEnglish (US)
Pages (from-to)105-109
Number of pages5
JournalMarine Ornithology
Issue number2
StatePublished - 2010
Externally publishedYes


  • Coloration
  • Kermadec Islands
  • Morphometrics
  • Sexual dimorphism
  • Sula dactylatra tasmani
  • Tasman Masked Booby

ASJC Scopus subject areas

  • Oceanography
  • Animal Science and Zoology


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