The San Diego pocket mouse (Chaetodipus fallax) is a rodent species in the family Heteromyidae.

Its length ranges from 170 to 200 mm and its weight is approximately 17–22 g. The San Diego pocket mouse is a homoeothermic endotherm with both hypsodont and lophodont teeth.

The San Diego pocket mouse is often a solitary animal, which makes it difficult to study its reproductive history.

Mortalities often result from predation, which increases in the spring when mice are actively foraging, reproducing and defending territories.

At higher speeds, the pocket mouse “gallops” by hitting the ground with both feet and using its tail for balance.

In this case, San Diego pocket mice are able to obtain their water through food or metabolic by-products.

If seeds are in short supply, individuals have been known to eat leaves, stems and insects to replace their normal diet.

The San Diego pocket mouse has a significant impact on the ecosystem in its ability to aerate the soil through burrowing.