The first and last photo of a Marias Islands mouse? | Article by Carlos Galindo

Carlos Galindo Leal

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The Marias Islands mouse was abundant until the 1970s. The introduction of rats (competitors), cats (predators), goats and deer (habitat modification) has dramatically reduced the population of this endemic species. In 2009, during a study on the environmental impact of prison expansion the man was caught, photographed and reinstated into their habitat by a supernatural personJuancruzado

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There were no photographs of these living animals. The observation was uploaded to the iNaturalistMX platform in 2013. No one has caught this small mammal in over 40 years, and it is highly likely that this speciesvery close to extinction

. It is critical to establish a comprehensive monitoring program on these Nayarit islands.

Mexico has a large number of islands that have served as laboratories for evolution: the Revillagigedo archipelago, Tres Marias, Cozumel and many islands in the Gulf of California. Species and subspecies different from those found on the mainland live here. Just as English naturalist Charles Darwin inspired part of his theory of evolution in the Galapagos Islands of Ecuador when he discovered the diversity of finch species, Mexico has also seen the phenomenon of new species forming due to geographic isolation.

However, like many other islands and archipelagos in the world, Tres Marias has suffered from the deliberate or accidental introduction of exotic species, which has severely impacted native species such as small rodent mammals. Asian rats, dogs and cats were introduced to these islands as owners’ pets, as were horses and goats, among many others.

Among the endemic species or subspecies of Tres Marias, which separated from the continent about five million years ago (late Miocene), there are about 20 species of plants, insects, birds, reptiles and mammals. Some species arrived around 120,000 years ago as sea levels dropped during the Pleistocene. The Marias Island Federal Penitentiary, established in 1905, was closed in 2019. In 2010 it was declared a biosphere reserve.

Fortunately, Mexico has succeeded internationally in ecological restoration of the islands, thanks in large part to a civil society organization: Grupo de Ecología y Conservación de Islas, AC. The organization, in collaboration with government agencies, has restored approximately 40 islands by removing introduced mammals (goats, dogs, cats, rats, mice) and recovering endemic species that are on the brink of extinction.

You may be interested in > Waterflakes, the world’s smallest flowering plant, are native to Mexico | Article by Carlos Galindo In 2023, the tireless naturalistJuancruzado

author of the Marias Islands mouse photograph, is recognized as the Mexican naturalist with the most species photographed on the iNaturalistMX platform, with over 6,700 species.

To learn more about endemic and exotic species, visit Somos Naturalistas and collaborate with your photos on iNaturalistMX. Author

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