Multi-regional Comparison of Scarring and Pigmentation Patterns in Cuvier’s Beaked Whales

Recent research on Cuvier’s beaked whales (Ziphius cavirostris) from the Mediterranean has demonstrated that sexes can be visibly distinguished in photos using sex-linked patterns of scarring density and pigmentation, even at age classes which are notoriously difficult to differentiate. Being able to apply this research to other populations would allow for better monitoring of population demographics and vital rates globally. This study uses Photo Identification Captures (PICs) of known sex, adult Cuvier’s beaked whales from three regions (Southern California, USA; Guadalupe Island, Mexico; and the Mediterranean Sea, Italy) to evaluate geographic variation in sex-linked patterns of scarring density and pigmentation. Standardized scarring density measurements from typical photo-ID views and Generalized Linear Models (GLM) were used to identify scarring density thresholds for sex at each region and for all regions combined to predict the sex of individuals. Scarring densities did not differ significantly among regions and thresholds calculated from any region correctly predicted the sex in other regions 92–98