Optimizing monitoring of an endemic terrestrial salamander (Speleomantes ambrosii): comparing cost-effectiveness of different methods for abundance estimation

Abstract

In order to correctly plan conservation and management of animal populations, it is fundamental to obtain reliable information on population abundance using cost-effective monitoring methods. In the case of small terrestrial vertebrates, capture–mark–recapture, removal sampling and counts of unmarked individuals have proven to be reliable techniques to estimate population abundance. In the present study, we applied a multinomial N-mixture modelling approach, performed through a double-observer sampling protocol, to estimate population size of the endemic terrestrial salamander Speleomantes ambrosii. We aimed at comparing cost-effectiveness of this protocol with those of other estimation methods (i.e., capture–mark–recapture and removal sampling), with particular attention to management and monitoring guidelines. The double-observer multinomial N-mixture protocol was the most cost-effective among the different methods: given its ease of application and cost-effectiveness, we encourage its employment for long-term monitoring and conservation plans of the near-threatened plethodontid salamander Speleomantes ambrosii.