The lemur leaf frog is a small tree frog native to the humid tropical forests of Central America, including Costa Rica, Panama and some parts of Colombia. Once considered a common species in Costa Rica, extensive habitat loss and fragmentation, irregular rainfall and a fungal disease – chytridiomycosis – have decimated its population over the past few decades. This species is now classified as Critically Endangered (CR) by the International Union for the Conservation of Nature (IUCN), with 80-95% of the population wiped out.

A new project led by NRI’s Dr Barbara Tiddi aims to reverse this decline by focusing on freshwater habitat restoration as an in-situ conservation action for the recovery of the lemur leaf frog (Agalychnis lemur) in Costa Rica. Amphibians (frogs, toads, newts and salamanders) face multiple pressures worldwide, but irregular rainfall has been singled out as the most important threat in the tropics. Waterbody or pond restoration, a relatively simple conservation practice has been shown to have a lasting positive impact on amphibian populations. However, its long-term effectiveness is still poorly understood.

In collaboration with Veragua Rainforest Foundation and the Distance State University of Costa Rica, this project will assess the effectiveness of pond restoration within the Lemur Frog Ecological Corridor in the Central Caribbean of Costa Rica. In 2022, local stakeholders established the corridor after acknowledging the area as a habitat for the country's last remaining wild population of the critically endangered frog species. The project team will conduct large-scale pond restoration at 30 locations within the corridor through water and vegetation supplementation which involves the improvement of water collection and vegetation. Dr Tiddi, Lecturer in Applied Ecology/Environmental Sciences at NRI said: ‘We will observe newly restored ponds over 12 months to monitor natural colonisation by amphibians, using passive sound recordings and a monthly visual search.’ Dr Tiddi and her team have already successfully used passive acoustic (sound) monitoring to detect calls from this species in the recordings collected and thus assess species presence. The next step is to apply this cost-effective method to collect long-term data on recolonisation of restored habitats.

Throughout the project, the team will also organise participatory consultations, working with local communities involved in ecotourism, to create guidelines for water body restoration. This participatory approach aims to build local capacity for biodiversity conservation and promote sustainable tourism.

This work will benefit the lemur leaf frog by increasing its connectivity – the ability of a species to move freely between habitats and ecosystems – but the benefits extend beyond that. ‘By improving habitats and engaging communities, we aim to create a sustainable model for amphibian conservation that can be replicated in other regions,’ Dr Tiddi explained. Local volunteers will also be trained in acoustic monitoring and supported in designing sustainable ecotourism activities. Training will sustainably increase the capacity of local communities by providing volunteers with transferable skills that can be applied to similar conservation-based initiatives, for example as eco-guides. It will also help establish a resource network of contacts among the Cabecar Indigenous Communities across the Indigenous territories, thus supporting wider collective decision-making.

Lemur leaf frogs are a vital part of their ecosystem, playing essential roles not only as predators of insects including pervasive pests like flies, but also as prey for birds, snakes and mammals. They are an indicator species, which means that their decline signals the threats to their entire tropical ecosystems. Improving forest habitats and water sources will also directly contribute to the recovery of over 20 other amphibians, including the critically endangered Starrett’s treefrog and the closely related blue-sided leaf frog. Saving the lemur leaf frog is therefore not just about helping one species, it is about securing the viability of entire rainforest ecosystems in which they live.

This work is funded by the Woodspring Trust, a conservation charity that supports projects with outstanding potential to achieve long-lasting nature conservation outcomes around the world.