Site selection for release of captive-bred Pickersgill’s reed frogs Hyperolius pickersgilli

Abstract

The successful release of captive-bred frogs to the wild can be hampered by uncertainty regarding the selection and state of proposed release sites. The Endangered Pickersgill’s reed frog (Hyperolius pickersgilli) has been captive-bred since 2013, to improve the understanding of its husbandry and ultimately for release to the wild at secure rehabilitated wetlands within the species’ native range in central coastal KwaZulu-Natal, South Africa. To facilitate selection of release sites, a bioblitz was conducted at four wetlands at which H. pickersgilli is present and at one potential release site. Wetlands occupied by H. pickersgilli have a dense and variable vegetation structure, comprising an overstory of tall, relatively broad-leaved emergent plants and an understorey of herbaceous plants. These wetlands have a variety of arthropods from various orders and families that are potential predators or prey. Predatory arthropods were present at all sites. Predatory fish and hetero-cannibalistic amphibians were captured at two sites each. The results of the bioblitz allowed us to ascertain what vegetation structure is suitable for H. pickersgilli, and which potential predatory fish and arthropods may be present at proposed release sites. Analysis of environmental DNA from water and soil samples might assist with the identification of fish, amphibian and some arthropod predators at potential release sites because phenotypic and genetic identifications matched in most cases. However, this was the case for relatively few potential prey species. Release sites for captive-bred H. pickersgilli should have a suitable vegetation structure as determined in this study, relatively few predators, and an abundance of small arthropods as prey, amongst other factors. The presence of certain insect species that are easily identifiable may be useful additional indicators of the suitability of potential release sites.