Before human settlement stretched across the Los Angeles basin, the land supported a diverse collection of native mammal populations. This wide array of species included native mice, shrews, squirrels, badgers, skunks, weasels, bobcats, coyotes, fox, deer, bats, mountain lions and even the grizzly bear.
Beginning in the late 1800s, the Los Angeles basin underwent a rapid increase in human population, which forever altered the fates of the native wildlife. The influx of human settlement led to dramatic reductions in native carnivore populations (especially Grizzly Bear and Mountain Lion), which affected the population densities of other wildlife in the basin. Accompanying the reduction of native carnivores, new human settlement introduced several nonnative mammals (Virginia Opossum and Eastern Fox Squirrel) that continue to survive in the LA area.
Mammals in the Baldwin Hills can be divided into three categories: