Tackling the tide: A rapid assessment protocol to detect terrestrial vertebrates in mangrove forests

Abstract

Globally, the occurrence of terrestrial vertebrates in mangrove forests is poorly documented, with little empirical data available. This knowledge gap is, at least in part, explained by the challenging survey conditions typically found in these environments. As an ecological understanding of ecosystems is essential to guide conservation management actions, a lack of baseline biodiversity surveys can leave ecosystems vulnerable to degradation. To address this, we developed and tested a rapid assessment protocol for tidal regions (RAPTR), that uses a range of techniques to detect mammals, reptiles and amphibians in mangrove habitat subject to daily tidal inundation. Our approach uses seven commonly used fauna detection techniques (live traps, camera traps, nocturnal transects, hair tubes, artificial terrestrial and arboreal refuges, and high-frequency acoustic monitoring). RAPTR was implemented over four consecutive nights at each of the 10 sites spanning temperate to tropical mangrove regions of Australia. We detected 65 species of terrestrial vertebrates, of which 42 species have not previously been reported in mangroves. We demonstrated that all techniques were robust to tidal inundation, and that four consecutive trap nights were sufficient to detect all taxonomic groups and most species in temperate regions, but that additional nights may be required in subtropical and tropical regions. We recommend RAPTR be used as a biodiversity assessment protocol to identify terrestrial vertebrates in mangroves to fill critical knowledge gaps about these important ecological communities, and one which can potentially be applied to other tidal ecosystems. Such a strategy would further our understanding of the ecological role mangroves play as habitat for terrestrial fauna, and help identify management strategies to aid the conservation of these declining ecosystems.