First observations on the courtship, mating, and nest visit behaviour of the Philippine crocodile (Crocodylus mindorensis) at the Cologne Zoo

Abstract

The aim of this study was to gain a better understanding of the social and in particular reproductive behaviour of the Critically Endangered Philippine crocodile. Crocodylus mindorensis has been a focus for international conservation breeding measures for about two decades. Since little scientific data have been gathered on the biology and ecology of the species so far, its breeding remains a challenge. In order to identify behavioural patterns that trigger courtship behaviour, and to determine when sociopositive interactions increase and the animals are ready for reproduction, a pair of two adult C. mindorensis at Cologne Zoo was systematically observed between August 2011 and July 2012 for a total of 583 hours. Observations took place using all occurrences recording and scan sampling, focusing on pre-, post- and actual mating behaviour. We present a detailed documentation of copulations with behaviours such as growling, roaring, and bubbling. Bubbling in both sexes was observed prior to copulations and decreased with the end of the mating season, supporting the assumption that it can be referred to as courtship behaviour. Behaviours that indicate the approach of the breeding season, such as approaches to the dividing slide, bubbling and nest building, could be distinguished. Our findings should help to improve breeding efforts under captive husbandry conditions and thus contribute to the conservation breeding of this highly endangered and difficult to keep crocodilian species.