The organization Re:wild announced that the Omilteme cottontail (Sylvilagus insonus), a species lost for more than a century, has been rediscovered in Mexico’s Sierra Madre del Sur. This find is of great significance for conservation and research.
A team led by José Alberto Almazán-Catalán, president of the Instituto para el Manejo y Conservación de la Biodiversidad (INMACOB), searched for the rabbit for more than five years in ten areas of the state of Guerrero. In seven of these regions, they were ultimately able to confirm the species. This success is part of Re:wild’s global “Search for Lost Species” program, which aims to rediscover species that have not been scientifically documented for decades.
Unique features of the Omilteme rabbit
(© IUCN Red List of Threatened Species, species assessors and the authors of the spatial data., CC BY-SA 3.0, via Wikimedia Commons)
The Omilteme rabbit is predominantly nocturnal, which makes the species difficult to observe. It differs clearly from other rabbits in the region due to its reddish-brown fur. Its most striking feature, however, is its short black tail—a contrast to the typical “cottontails” of other rabbits. In addition, it is overall smaller and has proportionally smaller ears. With a habitat restricted to the Sierra Madre del Sur, it is among the rarest and most endangered rabbit species worldwide. It lives mainly in dense cloud forests as well as pine and pine–oak forests at elevations between 2,133 and 3,048 meters.
The region around the village of Omilteme, which also gave the species its name, is considered a biodiversity hotspot. Here, 37 other mammal species share habitat with the Omilteme cottontail. The ecosystem benefits significantly from the rabbits, which enrich the soil through their droppings and promote the growth of unique plants. They also help keep invasive plant species in check.
According to the IUCN Red List, the Omilteme cottontail is classified as “data deficient”. The biggest threats to its survival include poaching and habitat loss from deforestation. The species had not been reported in the wild since the early 1900s.
Challenges and research progress
The search for the Omilteme rabbit began in 2019 in the forests around Chilpancingo, the capital of Guerrero, where the species was first documented in 1904. When no evidence was found there, the team expanded its search to higher-elevation regions. Conversations with villagers and hunters proved extremely helpful: local hunters reported regular sightings and described the rabbit as an important food source. This information helped narrow down the range more precisely. A few captured animals as well as a skin donated in 1998 ultimately provided concrete evidence that the species still survives.
Despite these advances, there is still much to learn—especially about the breeding season between January and June and the species’ exact population size. According to Almazán-Catalán, around 80 percent of the research goals have been achieved so far. The focus now is to develop protection measures in cooperation with the local population and authorities such as the National Commission for Protected Areas (CONANP).
The known range of the Omilteme cottontail lies within the Sierra Tecuani Biosphere Reserve. Nevertheless, there are currently no specific conservation measures for the species. Re:wild hopes the new findings will help develop targeted strategies to protect the rabbit.
A milestone for conservation
Christina Biggs, Re:wild’s lead for lost species, praised the team’s determination and effort: “This search was full of unexpected twists and combined interviews with innovative techniques like drone deployments to find this small rabbit.”
The rediscovery of the Omilteme cottontail underscores the importance of long-term research and local cooperation. Hopefully, this success will not only lead to conservation measures for this species, but also inspire other projects in global conservation.
The find is part of Re:wild’s global “Search for Lost Species” program, which aims to rediscover species that have not been scientifically documented for at least ten years. Within this framework, 13 species have already been rediscovered, including De Winton’s golden mole, Attenborough’s long-beaked echidna, Wallace’s giant bee and the Fagilde trapdoor spider.
About the author: Doreen Fräßdorf
Doreen Fräßdorf is the author and publisher of artensterben.de. She researches and writes about extinct and endangered species in the modern era, with a focus on red lists, scientific studies, historical sources, and current conservation efforts. The goal is a clear, evidence-based overview of biodiversity loss and species protection.
She is also the author of a non-fiction book about extinct modern-era mammals.
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