Possible extirpation of the threatened Malagasy poison frog Mantella cowanii

New research highlights the precarious status of one of Madagascar’s most threatened amphibians, the harlequin mantella (Mantella cowanii), revealing small population sizes and the possible extirpation of the species from several of its historic habitats.

The findings underscore the urgent need for targeted conservation action to prevent the species from slipping further towards extinction. The findings are published in the journal PeerJ.

A dire situation

Amphibians around the world are facing unprecedented population declines, and Mantella cowanii is no exception. The study, which focused on confirming the frog’s presence at historical localities and estimating its population size and survival rates, paints a concerning picture.

Out of the 13 known localities for M. cowanii, the frog was detected in only eight, with three populations potentially extirpated. However, the research also uncovered two new populations, offering a glimmer of hope amidst the otherwise bleak outlook.

Repeated annual surveys at three sites revealed population sizes ranging from as few as 13 to 137 adults, with one site experiencing an alarming 80% reduction in population size from 2015 to 2023. The study also discovered that M. cowanii has a relatively slow life history pace, with adult survival rates between 0.529 and 0.618, and a maximum lifespan in the wild reaching nine years or more. This slower life history makes the species particularly vulnerable to extinction.

The primary threats to Mantella cowanii include illegal collection for the international pet trade and ongoing habitat degradation. These pressures are compounded by the frog’s limited distribution and small, isolated populations, which further increase its extinction risk.

Conservation recommendations

In light of these findings, the researchers recommend immediate and sustained conservation efforts. Key actions include:

1. Continued population monitoring: Ongoing monitoring of M. cowanii populations is critical to track trends, measure the effectiveness of conservation actions, and detect declines before they become irreversible.
2. Reassessing the IUCN Red List Status: Given the recent population estimates and trends, there is a strong case for reassessing the species’ status on the IUCN Red List. Mantella cowanii was last assessed in 2014 as Endangered, but it may now qualify for the more severe Critically Endangered status.
3. Engaging Local Communities: Conservation efforts should involve local communities in monitoring programs, which can foster pride and support for the species while adding value to conservation initiatives.
4. Further Research: Additional research is needed to better understand the relative impact of threats such as disease, illegal trade, and habitat loss. This knowledge is essential to developing effective conservation strategies.

Global implications

The challenges faced by Mantella cowanii are emblematic of a broader global trend in amphibian population declines. As amphibians are often indicators of environmental health, the decline of M. cowanii signals broader ecological challenges that could have far-reaching impacts.

The time to act is now. Conservationists, researchers, and policymakers must come together to implement the recommended actions and ensure the survival of Mantella cowanii. Without decisive intervention, we risk losing this unique species forever.