Sex identification of Humboldt penguins using a morphometric analysis

Abstract

Primorsky Aquarium keeps a population of 32 Humboldt penguins. The employees of Ornithology Department are faced with a problem of sex identification of 18 immature/young penguins. Male and female Humboldt penguins have not significant differences in feather coloration, so reliable sex identification by direct observation is not possible. The most reliable ultrasound and genetic methods require special equipment, reagents and qualified specialists as well as provoke stress that is dangerous for the health of the birds. Sex identification by morphometric parameters for captivity birds is more preferable, since this procedure is non-invasive, does not require special equipment and specialists. We have performed a statistical analysis of measurements of the beak length in 3 variations, of the dorsal part of flipper length, and weight of females and males of the studied group. For the first time, we have added to the analysis the length of the beak from the nostril, which was not previously taken into account. It has been found that the use of 4 traits simultaneously in the analysis does not demonstrate a significant correlation with the sex of the bird, and therefore is not suitable for the sex identification of penguins. The most consistent features for correlation analysis were the beak length and the flipper length. The maximum grouping of birds by sex within the study group was observed while comparing these morphometric characteristics.