Threatened and Endangered Species
Valley provides important habitat, supporting a diversity of interdependent species

Definition
Natural rates of extinction are accelerated by human action, primarily through the development of land and the cultivation of new agricultural areas, both of which reduce habitat. Add past overhunting, pollution, erosion from overgrazing, crop conversion, and the introduction of non-native species, and humans can have quite a collective impact on the natural environment.

Why is this important?
Losing one type plant or animal can produce serious impacts that are not immediately apparent due to the intricate interdependence of all living things. For example, the Giant Kangaroo Rat, found in the southwestern portion of the San Joaquin Valley, is the prey of the San Joaquin Kit Fox. By creating burrows, it increases plant productivity of San Joaquin Woolly-threads and provides shelter for the Blunt-nosed Leopard Lizard and the San Joaquin Antelope Squirrel. All of the mentioned species are listed as endangered or threatened--loss of one species would affect the others’ chances of survival.

How are we doing?
Three-quarters of Valley lands are home to at least seven threatened and endangered species. Except for the region’s urban areas, the entire Valley is home to at least one or more threatened and/or endangered animal species. The number of listed threatened and endangered animal species found in the Valley ranges from a high of 33 in Fresno County, to a low of 9 in Kings County.

The information presented regarding listed endangered and threatened species is a snapshot of current conditions. No trend or indication of performance in conservation efforts is presented due to the dynamic nature of the species listings and the varying stages of Habitat Conservation Plans, in which habitat and animal populations are more thoroughly identified.

Assessing Habitat
Assessing animal populations is difficult. The most comprehensive information on California plant communities and animal habitats comes from the Gap Analysis Project, administered at the University of California at Santa Barbara. Gap data includes information on land cover and vegetation type, as well as complete listing of the vertebrate species associated with different vegetation layers. For each species, habitat quality is rated on a 1-to-5 scale (with 5 being the highest quality habitat).

By multiplying each Threatened and Endangered species present in the Great Valley by its respective habitat quality rating, and then summing the result over all Threatened and Endangered animal species, it is possible to calculate a single multi-species index of habitat quality. However, the indices - which were calulated at UC Berkeley for this report - do not indicate habitat quality for an individual species, or the probability that a particular animal species will actually be found on site.

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Original text found in: Environment Indicators Report 2001