First insights on the ecology of two Critically Endangered frogs from Madagascar

by Bela Barata - November 11, 2020

Anodonthyla vallani and Anilany helenae are microhylid frogs, endemic to Ambohitantely Special Reserve, Madagascar. We find them in high-altitude forests at around 1500 m elevation.

Targeted species

Anodonthyla vallani occupies tree trunks several meters above the ground and uses tree holes as breeding sites. Anilany helenae is terrestrial and occupies the leaf litter, breeding is unknown and possibly involve terrestrial nests.

Both species are Critically Endangered and listed as priority EDGE species. They are endemic to Ambohitantely and the reason for its designation as an Alliance for Zero Extinction site. Ambohitantely represents the only protected area of humid forest on the central plateau of Madagascar. It is part of the Southern Africa Central Madagascar ecoregion and is classified as Critically Endangered by WWF.

 

Durrell’s work to save these species from extinction

In 1996 and 1997, a study looked at the effects of fragmentation on amphibian populations at Ambohitantely. This study resulted in the discovery of A. helenae and later in the description of A. vallani. Since then, no research group conducted further amphibian surveys. Although isolated populations of both species persisted in the fragments, little information was available to inform their management and conservation interventions.

In 2018, Durrell initiated the first dedicated amphibian surveys looking at these endangered species in Ambohitantely in 20-years. Whenever she can, Kat Mullin, PhD student at Cardiff University, updates us with news from the field (February update and September update in our blog, also on her personal blog katribbetson). As a result of this long-term dedication, our team has produced the first ever population estimates for these two endemic and Critically Endangered frogs from Ambohitantely Special Reserve.

Research results

Our findings support previous observations related to habitat use, showing that species are indeed influenced by vegetation structure, such as bamboo numbers and canopy cover. Despite having moderate to high occupancies, we had relatively low population estimates for our sampled population. Given the small population sizes and close relationship with vegetation structure, continuous habitat loss may have drastic consequences for their populations in the long-term.

Since 2005, the annual deforestation rate has progressively increased in Madagascar. Although fragmented, Ambohitantely is one of the last refuges of humid forests in the central plateau. However, it suffers from further forest loss despite being a Special Reserve and having a management plan in place. Our results serve as baseline information to describe future population trends and further understand the impacts of forest fragmentation on these species.

Aligned with the SAFE strategy, we are looking at implementing a long-term monitoring programme for threatened amphibians in Ambohitantely. We aim to further develop local capacity that can contribute to effectively deliver our long-term plans.

Details of these results are currently in press, so watch this space to follow up on our research news!