Bats are critical to ecosystem function (e.g. consuming vast numbers of insects, pollinating certain species of plants, distributing seeds of fruits). As the primary predator of nocturnal insects, bats occupy a unique ecological niche. Twenty-five species have been recorded in the state of California; of those 25, almost half have been detected in the Coastal Southern California national parks. This makes parks an excellent location to study bat populations.
- Despite the lack of suitable habitat, a 2002 survey by USGS detected four species at Cabrillo National Park including the Western Red Bat (Lasiurus blossevillii), Mexican Free-tailed Bat (Tadarida brasiliensis), Big Brown Bat (Eptesicus fuscus), and Big Free-tailed Bat (Nyctinomops macrotis).
- Eleven of California's 25 species of bats have been documented on the Channel Islands (Santa Cruz Island), including a colony of Townsend's Big-eared Bat, one of only a handful of colonies in the state. Bat foraging and roosting habitat have been significantly impacted by historic grazing and vegetation change.
- As many as 22 species of bats could potentially occur at some season in the Santa Monica Mountains, although ten of these would be considered rare or vagrant. The last survey conducted in the mountains verified eleven species of bats.