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Thomasset’s Seychelles Frog

Sooglossus thomasseti


Thomasset’s frog is the largest of the Seychelles’ native frogs, reaching a maximum length of 55 mm, and is Critically Endangered.

This species is part of the Sooglossidae (Seychelles frog) family and the Seychelles frog diverged from their closest ancestors around 100 million years ago. This is around the same time humans and elephants last shared a common ancestor. This species is a rock climber, and is most often found at night sitting on rocks and large boulders.

Thomasset’s frog is the rarest frog species in the Seychelles and is currently threatened by habitat degradation, mainly due to fire and invasive species, and climate change. It is also at risk because of its small, fragmented range; species that are only found in a very small area are more likely to be affected by localised ecological disasters or climate change.

Thomasset’s frog occurs within the 30.5 km² Morne Seychellois National Park in Mahé, whilst its population on Silhouette Island falls partly in the site of a conservation project that has been established on the island by the Nature Protection Trust of the Seychelles. Many small reserves on the islands have been set up by the Seychelles Government and independent agencies to protect specific species and general habitat areas.

  • Order: Anura
  • Family: Sooglossidae
  • Trend: decreasing
  • Size: 55mm

EDGE Score

EDGE Score: 5.72 (?)
ED Score: 50.86 (?)
GE / IUCN Red List (?)
Not Evaluated Data Deficient Least Concern Near Threatened Vulnerable Endangered Critically Endangered Extinct in the Wild Extinct


Thomasset’s frog is restricted to Mahé and Silhouette Islands in the Seychelles, occurring at relatively high elevations: over 350 metres above sea level. The area of space in which this species lives in is probably less than 20 km².

Habitat and Ecology

This species is restricted to relatively undisturbed habitats in wet rocky areas along streams or dry streambeds. They occur in areas of high levels of mist and cloud cover. It breeds by direct development; bypass a larval stage and emerge from the eggs as miniature version of the adult. Closely related species guard their nests so it is likely that the female in this species also guards her nest. Their call is longer than other closely related species and the first guttural note is repeated 3 or 4 times, rather than just once.

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Conservation Actions

For each key category of conservation action, we calculated a conservation attention score based on expert information. In this graph, a higher score means the action is being carried out more intensively over more of the species range. The colour shows how important each action is considered to be for the conservation of this species.

Engaging stakeholders
Addressing threats
Status of knowledge
Management plan
Capacity building
Behaviour change
Awareness raising
  Score: 100 means the activity occurs at high level across more than 75% of the species range
Very Low

Overall Conservation Attention

We combined all of the expert information on conservation actions to calculate an overall conservation attention score for this species. Please help us to reach our goal of establishing dedicated conservation attention at “High” levels for all EDGE species.

Very Low Low Medium High

More information

Recent studies have grouped all possible conservation activities for any species into nine key categories (Washington et. al 2015). For each action, we asked experts for each species to assess the extent to which that action is being carried out and how much of the species’ range that action occurs in. For each action we used these two pieces of information to calculate the conservation attention score per action. A score of 100 means that the action is being carried out to a high level across at least 75% of the species range. We then combined the scores for all actions into an overall conservation attention score for the species. The experts also judged how important each category was to the conservation of that particular species.

This wordcloud illustrates the threats facing this species. The size of each word indicates the extent of a species range that is affected by that threat (larger size means a greater area is affected). The colour of the word indicates how much that threat impacts the species (darker shades of red mean the threat is more severe).

Habitat change Fire Invasive species

Threat wordcloud key:

Small area affected
Large area affected
Least severe
Most severe
Severity unknown
Source: The IUCN List of Threatened Species. Version 2017.1.
Available at:

Download the survival blueprint for this species below. Each survival blueprint is compiled by an EDGE fellow working on the species with input from collaborators and stakeholders. The survival blueprint provides a status review (information on the distribution, protection status, habitat & ecology, threat and stakeholder analysis) and more information on the action programme listed here. 

Vision (30-50 years)

There are viable sooglossidae population on all the three islands (Mahé, Praslin and Silhouette).

Goal (5-10 years)

To ensure that there is a long-term monitoring programme in place on all the three islands (Mahé, Praslin and Silhouette), and reduce data deficiency on sooglossid frogs’ ecology and the risk of chytrid disease from arriving into the country.


Establish a long-term monitoring programme for the conservation of sooglossid frogs within protected areas on all three islands (Mahé, Praslin and Silhouette). Critical
Review and update the Sooglossidae Conservation Action Plan (Survival Blueprint) through a stakeholders’ participatory process. Critical
Develop and enforce legislation to reduce the risk of the chytrid disease from arriving into the country. Critical
Status of Sooglossidae is known through research on population size, ecology and behaviour of all four species. High
Develop partnership between different organisations managing protected areas in Seychelles to facilitate sharing of information. High
Actively involve University of Seychelles’ students in field research and scientific data analysis, and other conservation activities. Medium
Increase visibility of Sooglossidae nationally to attract more funding. Low

Targeting the Seychelles ‘EDGE-zone’

  • Locations: Seychelles
  • Active dates: 2012 - 2015
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James Mougal

  • Project name: Improve our knowledge on sooglossid frogs distribution & abundance and develop a monitoring protocol
  • Project site: Mahé, Praslin and Silhouette islands, Seychelles
  • Active: 2014 - 2017
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