The conservation breeding of two foot-flagging frog species from Borneo, Staurois parvus and Staurois guttatus

Abstract

The Bornean frogs of the genus Staurois live exclusively along fast-flowing, clear water rainforest streams, and are famous for displaying a variety of visual signals, including foot flagging. Their extraordinary behavior, and the continued loss of their natural habitat due to deforestation and subsequent pollution, make them a group of target species for captive breeding, as well as behavioral research. The Vienna Zoo has pioneered in the development of a research and conservation project for S. parvus and S. guttatus. We implemented two breeding and research arenas, offering an artificial waterfall and different options for egg deposition in a bio-secure container facility. Two months after introducing the frogs, we observed amplectant pairs and the first tadpoles. Vienna Zoo is the first zoo worldwide that has succeeded in breeding foot-flagging frog species and meanwhile has recorded over 900 tadpoles and at least 470 juveniles. One of the most striking observations has been the use of foot-flagging signals in recently metamorphosed S. parvus. This corroborates our assumption that “foot flagging” is employed as intraspecific spacing mechanism. The breeding success of two Staurois species at the Vienna Zoo can help in species conservation as it increases our knowledge on conditions necessary to breed tropical stream-dwelling anuran species found to be particularly threatened in nature. Furthermore,the captive colony provides research conditions to better understand the role of “foot flagging” as a visual signal component in anuran communication.