Getting fired up for frogs


A novel approach to conserving a Critically Endangered frog

Alouise Lynch, Bionerds PTY Ltd.


Amidst a field of agricultural development, the Klein Swartberg Mountain towers above the town of Caledon in South Africa’s Western Cape Province. This lone mountain is home to the only known populations of the Critically Endangered (IUCN Red List 2016) Rough Moss Frog (Arthroleptella rugosa), an amphibian species restricted to this mountain. For this reason, the mountain was deemed an Alliance for Zero Extinction Site in 2017.

The Alliance for Zero Extinction (AZE) is a joint initiative of biodiversity conservation organisations from around the world working to prevent extinctions by promoting the identification and ensuring the safeguard and effective conservation of key sites that are the last remaining refuges of one or more Endangered or Critically Endangered species.

Alliance for Zero Extinction website, July 2023

Bionerds have been implementing this project for the Endangered Wildlife Trust since 2019. The Endangered Wildlife Trust’s (EWT) Threatened Amphibian Programme (TAP) Conserving Threatened Frogs of the Western Cape  Project includes the Rough Moss Frog as a species of conservation concern given its restricted range. Furthermore, it still faces grave threats within this range, including habitat loss caused by alien invasive plants and frequent unplanned fires, which have led to a severe population decline (IUCN Red List 2016). Long-term acoustic monitoring by Cape Nature and Stellenbosch University documented this decline categorically, showing how the type (original) population had all but disappeared completely.

During our surveys in May 2020, a marching forest of alien vegetation, mostly Pine, was observed engulfing the then-only known populations of Rough Moss Frogs. It became evident that rapid intervention was needed to save and secure these populations. Unfortunately, the Covid-19 epidemic halted all efforts to implement interventions in 2020.

In 2021, the project was awarded a Rapid Action Grant from the IUCN Save Our Species fund and the European Union. This grant enabled us to create a firebreak around the Rough Moss Frog populations. We had limited time to implement this burn because the pine trees were starting to cone, and we had to act hastily to prevent another season for them to set seed. In March 2022, we worked with the local conservancy and landowners to implement a controlled ecological fire – the first time globally that prescribed fire was used as a management tool to reduce alien invasive vegetation threatening a frog species from extinction.

The Overberg District Municipality Fire Department and the Greater Overberg Fire Protection Association oversaw the burn and did a sterling job of ensuring all possible precautions were taken for the implementation of the burn, all permits were issued, and on the day, all hands were on deck to start, maintain, and close off the burn. Unfortunately, unforeseen windy conditions developed late in the day and the fire managed to break through several points and burnt a larger section of the mountain than was planned. Over 4,000 hectares were burnt, which is good news for pine eradication efforts but requires carefully planned follow-up management over a larger area. Bionerds have assisted with this through drone-mapping of priority areas.

A site visit following the fire in April 2022 confirmed the presence of Rough Moss Frogs, and in July 2022, we were relieved to hear the species calling at the sites of all known populations. In May 2023, multiple individuals were heard in an area where none were heard or recorded before the fire. During subsequent surveys, we discovered numerous additional populations of this species across the mountain – a big win for the project and the species!

This year, between July to September-  the coldest and wettest months– when these frogs breed, we will implement acoustic surveys to determine the presence or absence of Rough Moss frogs in all previously recorded sites. These surveys use three audio devices called Song Meters – a six-microphone array deployed at each population site for roughly an hour per site. The arrays record all frog calls during that period, and we can then use the audio file to estimate density and determine how many Rough Moss Frogs are present in each specific population at that specific time. We will be doing this for five years, each breeding season, to determine the effectiveness of the fire on the preservation of the sites, as well as capturing the rate of recovery of the frog populations at each site.

The landowners that are part of the Klein Swartberg Conservancy all support the protection of this species – and Bionerds and the Fynbos Trust have developed an alien clearing plan to guide the clearing of alien invasive vegetation from the mountain over the next decade. This alien vegetation clearing operation across the mountain creates jobs for local people from the Caledon area. This project is challenging, but we are positive and excited about the future of this tiny frog due to multiple partners working together towards protecting the species and its important fynbos habitat.

This project is funded by the IUCN Save Our Species and the European Union. The IUCN Save Our Species aims to improve the long-term survival prospects of threatened species. It also focuses on supporting the species’ habitats and working with the communities sharing this habitat. It achieves success by funding and coordinating conservation projects across the globe. The Member States of the European Union have decided to combine their know-how, resources, and destinies. Together, they have built a zone of stability, democracy, and sustainable development whilst maintaining cultural diversity, tolerance, and individual freedoms. The European Union is committed to sharing its achievements and values with countries and peoples beyond its borders.