Aegialomys

These mice are sometimes called coastal or beach rice rats, and they belong to the family Cricetidae, which includes many of the New World rats and mice. Their specialized preference for dry coastal habitats, such as scrublands, deserts, and thorny forests stretching near the ocean, makes them stand out among their relatives. In contrast to the lush rainforests where many South American rodents thrive, Aegialomys species have adapted to some of the driest and harshest environments on the continent.

Physically, they are medium-sized mice with soft, grayish to brown fur above and paler underparts. Their tails are typically long and can sometimes be as long as their bodies, helping them balance as they move through brush and sandy terrain. Their subtle coloring allows them to blend easily into the dry, rocky, or sandy ground, making them less visible to predators like owls, foxes, and snakes. As nocturnal animals, they spend the daylight hours hidden in burrows or thick vegetation and emerge at night to forage. Their diet is omnivorous, consisting mostly of seeds, fruits, and insects, which makes them resourceful feeders in an environment where food can be scarce.

By living in coastal deserts and scrublands, they fill an important role in seed dispersal and insect control in ecosystems that are often overlooked compared to rainforests or high mountains. Some species, like Aegialomys xanthaeolus (the yellowish coastal mouse), are relatively common within their limited range, while others remain poorly studied, with very little known about their population trends or habits. Their restricted distribution also makes them vulnerable to habitat loss, as coastal development and agriculture can disrupt the fragile ecosystems where they live.