Can Black Petrels be sexed by measuring them?

Claudia Mischler (Wildlife Management International Limited) and colleagues have published in the New Zealand journal Notornis on sexing ACAP-listed Black Petrels Procellaria parkinsoni utilizing morphometrics.

The paper’s abstract follows:

“Discriminant function analysis (DFA) is widely used to determine sex in the field from morphological measurements of bird species with monomorphic plumage.  Sexual dimorphism was examined in black petrels (Procellaria parkinsoni) using 7 external measurements of adult birds breeding on Great Barrier Island, New Zealand.  Males were significantly larger than females in absolute values of all measurements except for tarsus.  Two stepwise DFA models were developed.  The first used all 7 parameters, while the second model used only 6 parameters in order to increase sample size.  Model one and two showed an 88 and 82% classification success, respectively, most likely due to the high overlap in measurements between males and females.  These canonical functions were not accurate enough for field surveys, but may be improved using a larger and more representative sample size.”

Black Petrel, photograph by New Zealand Department of Conservation

Reference:

Mischler, C.P.,Bell, E.A.,Landers, T.J. & Dennis, T.E. 2015.  Sex determination of black petrels (Procellaria parkinsoni) using morphometric measurements and discriminant function analysis.  Notornis 62: 57-62.

John Cooper, ACAP Information Officer, 06 August 2015