Cave-dwellers No More

The emergence of bats each night is a common summer sight here in the Eastern Sierra, and, while watching them flit about to catch their prey, one may secretly hope that mosquitoes are their favorite food.

With some bat species eating at least 6,000 mosquito-sized insects each night, the capacity of bats to consume large numbers of insects plays a key role in ecosystem balance.

Bats account for a whopping one quarter of all mammal species worldwide, and seventeen species are found locally.  One key factor in determining bat populations is the availability of roosting sites. Some species, like the Western pipistrelle (Pipistrellus hesperus) have been said to inhabit unused Kangaroo Rat burrows. Others, like the Townsend’s big-eared bat (Corynorhinus townsendii), have adapted to roosting in local abandoned mines. 

This adaptation has served the Townsend’s big-eared bat well, for it naturally roosts in caverns which rarely occur in this area.  Thus, abandoned mines have created new roosting habitat for this species.  This is important because the Townsend’s big-eared bat is a California Species of Special Concern with overall population numbers on the decline.  Another factor that affects their population numbers (and an indicator that they are a sensitive species to habitat change) is that they also require undisturbed foraging habitat to thrive—which they find in the sparsely-populated Eastern Sierra. 

Helping creatures like the Townsend’s big-eared bat maintain a critical foothold in this region highlights the importance of the ESLT’s mission to preserve rural landscapes—though we can’t make any promises about the mosquitoes.

Why do bats hang upside down?
Besides providing bats with roosting space away from predators, bats actually have specialized tendons that hold their toes in place so that they are able to cling to their roosts without expending any energy; in fact, bats must flex their muscles in order to let go of the roosting surface.

 

 

How do bats see in the dark?

With a unique communication and navigation by echolocation surpasses current scientific understanding; bats can “see” everything but color, and in total darkness they can detect obstacles as fine as a human hair—a system billions of times more efficient than anything developed by modern science.

Bat species in the Eastern Sierra
Scientific name/Common name                                                        State Status*      
Corynorhinus townsendii (Townsend’s Big-eared Bat)                        CSC**             
Euderma maculatum (Spotted Bat)                                               CSC                  
Pipistrellus hesperus (Western Pipistrelle)                                               
Lasionycteris noctivagans (Silver-haired Bat)                                         
Lasiurus blossevillii (Western Red Bat)                                                                  
Lasiurus cinereus (Hoary Bat)                                                                        
Antrozous pallidus (Pallid Bat)                                                       CSC       
Eptesicus fuscus (Big Brown Bat)                                                                        
Myotis californicus (California Myotis)                                                               
Myotis ciliolabrum (Western Small-footed Myotis)                                 
Myotis evotis (Long-eared Myotis)                                                        
Myotis lucifugus (Little Brown Bat)
Myotis thysanodes (Fringed Myotis)
Myotis volans (Long-legged Myotis)
Myotis yumanensis (Yuma Myotis)
Tadarida brasiliensis (Mexican Free-tailed Bat)

*State status as defined by the California Department of Fish and Game’s July 2005 list of Special Animals.
**CSC = California species of special concern.

Compiled by:
Debbie House
Wildlife Biologist
Bishop,  CA

For more information about bats, see www.batcon.org