The parks' mammal list includes common species such as the ornate shrew, big brown bat, coyote, black bear, ringtail, mule deer, and pika; and several rare species, such as the wolverine, badger, bighorn sheep (federally endangered), and many rare bats – half of which are state or federally listed. It also includes several exotics, including the Virginia opossum, beaver, and muskrat. 

Exotics pose many unique management problems including competition, direct displacement, and direct competition with native species. Exotic beavers alter the riparian habitat and are therefore monitored regularly. Feral cats kill native species, pigs tear up the soil, and cattle graze and trample native vegetation and thus must be excluded from the parks. Since 2001, cattle fencing has been added along more of the parks' boundary.

The loss of a natural fire regime is also of great concern to resource managers. Fires affect everything from moisture availability to vegetation composition and structure to soil nutrient levels. A nine-year study has been completed on the effects of fire on small mammal populations in Mineral King. The US Geological Survey's Biological Resources Division has done a second study on fire effects on ecosystems (including small mammals) in conjunction with several USDA Forest Service sites as part of the Joint Fire Science Program.

Habitat fragmentation affects many species, but especially ones with large home ranges, and those that are migratory in nature. Some park species, such as the Pacific fisher (under consideration for listing as federally endangered or threatened), are now isolated from populations north of the parks. In 1999, the US Forest Service conducted a partial status assessment of the parks' fisher population. Several subsequent studies have also been done, and some are on-going. Sierra Nevada Bighorn Sheep are currently listed as endangered under both federal and state law. Their numbers are greatly reduced due to effects of mountain lion predation. Mountain lion predation of sheep at lower elevations has restricted sheep from using important portions of their winter range. The result is reduced winter forage and poorer nutrition for both adults and young sheep. There is also sustained risk of disease transmission from domestic sheep. The California Department of Fish and Game is working with the U.S. Fish & Wildlife Service to prepare a recovery plan. Continued protection of fisher, bighorn sheep, and other species and populations within the parks and across agency boundaries holds great significance for their future survival.

Finally, direct human disturbance to wildlife in the parks comprises a major part of our work. Beyond the effects of visitation that one would expect (automobile traffic, trails, etc.), we have two other unusual circumstances. One is the effect developed areas have on marmots. In Mineral King, parking lots and cabins were built in an area occupied by marmots, creating attractants for their desire for cover and new opportunities for their chewing habits and quest for minerals. During the spring, the marmots regularly take apart the under-side of numerous vehicles to go after anti-freeze. The result is disabled vehicles, cabins with holes chewed through them, and marmots consuming potentially harmful chemicals. After extensive monitoring, biologists found that in a single year, several hundred marmots have been involved. Some marmots have even exited the park when vehicles were driven away with an unsuspecting marmot hidden under the hood. The distance record to date is when one marmot caught a ride to Santa Monica, CA. The current solution to the problem is chicken wire around vehicles in the spring - another alternative would be to eliminate the parking lot. 

The second special circumstance is the effect of the availability of human food on black bears. For more information, please visit our black bear page, and please remember to store all food properly when visiting the parks.

As with all resources, inventory and monitoring are vital and we expect to begin a bat inventory and an inventory for rare mammals in 2003.