Tres Marías Cottontail

Fascinating facts about the Tres Marías Cottontail

• Found only on three Mexican islands in the Pacific, the Tres Marías cottontail has shrunk to fewer than 500 individuals in the wild — making it one of North America's rarest rabbits. It survived the last ice age on those same islands, cut off from the mainland for over 10,000 years, evolving in isolation until humans arrived. Today it faces competition from introduced species and habitat loss on land masses smaller than San Francisco.
• Unlike most cottontails that live on open grassland, Tres Marías rabbits are forest dwellers, hiding in dense scrub and emerging at dusk to feed on low vegetation. This shy, nocturnal habit made them nearly invisible to science until the 1980s — they'd been overlooked for over a century despite living on inhabited islands. Their preference for thick cover is now their only shield against extinction.
• Island rabbits often grow smaller than their mainland cousins — a pattern called island dwarfism — but the Tres Marías cottontail bucks that trend. It weighs roughly 400 grams, similar in size to the mainland eastern cottontail despite millions of years of separate evolution. Scientists still debate why this isolated population avoided the size reduction that typically defines island mammals.
• The Tres Marías cottontail shares its island home with introduced coatis and other predators that arrived with human settlement, predators it evolved without and has no instinctive fear of. Archaeological evidence shows rabbits thrived on these islands for thousands of years before Spanish colonisation in the 1600s. In just four centuries, introduced species have pushed it toward extinction — a reminder of how fragile island life becomes when the rules change.
• Conservation breeding programs now hold captive populations of Tres Marías cottontails in Mexican zoos and research centres, a genetic insurance policy against extinction. Without these breeding colonies, this species would likely vanish within a decade. It represents a bet that humans can reverse the damage of introduced species — and that isolated island populations, once lost, can be restored to land that remembers them.

At a glance

About the Tres Marías Cottontail

In the lush, volcanic landscapes of the Tres Marías Islands, a delicate, large-eyed creature darts through the underbrush, its soft grey fur blending seamlessly with the dappled shade. The Tres Marías Cottontail, a gentle and elusive denizen of this remote archipelago, moves with a quiet urgency, its powerful hind legs propelling it through the dense vegetation with a swift, economical grace. As it vanishes into the shadows, its very existence seems a fleeting, ephemeral wonder, a poignant reminder of the fragile beauty that teeters on the brink of extinction.

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