Olive Grass Mouse (Abrothrix olivacea) lives in temperate grasslands across South America. It feeds on seeds and insects. Its conservation status is Least Concern.
Fascinating facts about the Olive Grass Mouse
- The olive grass mouse inhabits Hornos Island, which places it at the extreme southern limit of any land mammal. Its distribution also stretches across southern Chile, Patagonia and the islands of Tierra del Fuego, showing a broad latitudinal range. Because no other terrestrial species is recorded farther south, this isolated population holds the record for the world's southernmost land mammal.
- In 2026 a scaffold-level genome assembly for the olive grass mouse was released, marking the first complete genetic blueprint for any sigmodontine member of the tribe Abrotrichini. The assembled genome measures about 2.25 Gb and achieved a BUSCO completeness of 98.6%, indicating high quality. Researchers identified 21,476 protein-coding genes, providing a valuable resource for future studies of this rodent lineage.
- The massive 1990 seeding of the bamboo Chusquea valdiviensis produced seed over more than a million hectares, which then died and left abundant food for rodents. This event triggered a noticeable rise in olive grass mouse numbers, although the increase was smaller than that seen in the rice rat Oligoryzomys longicaudatus. Because many seeds remained in spikelets for a year, subsequent rodent population peaks occurred in the following years.
- In Chile it sometimes occupies burrows made by the coruro (Spalacopus cyanus). The mouse is mainly active during daylight hours, which matches its mostly diurnal habit. In grassy areas it builds run-way networks and constructs nests of grasses within tussocks, among roots or under rocks, and it is also capable of climbing and digging. Using these shelters and foraging routes it exploits berries, seeds, shoots, leaves, fungi and small invertebrates.
Sources
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At a glance
RangeSouth America
HabitatTemperate grasslands
DietSeeds and insects
About the Olive Grass Mouse
In the lush undergrowth of South America's temperate forests, the Olive Grass Mouse weaves a secretive existence, its tawny coat blending seamlessly with the rustling grasses as it forages for seeds and fruits with quiet industry. With each nimble step, it navigates a intricate network of hidden pathways, its large eyes watchful for the slightest hint of danger in this verdant world. As it darts through the shadows, its very presence seems a testament to the enduring power of adaptation, a small but vital thread in the rich tapestry of life that envelops this enchanted landscape.
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