Dipodomys merriami parvus

This subspecies has lost 96% of its original distribution. As of 2020, there are only three small, isolated extant San Bernardino Kangaroo rat populations remaining that are subject to a number of realized threats.

The current San Bernardino kangaroo rat range includes three small, disjunct populations (Conservation Units) comprising approximately 7,112 ha (17,573 acres) of modeled habitat in the floodplains of the San Ana River and its tributaries, Lytle and Cajon Creeks, and in the San Jacinto River in Riverside and San Bernardino Counties, California, USA (USFWS 2020a). The range extent of this taxon, as determined by concave hull analysis of Element Occurrences and locations derived from unprocessed CNDDB location data, is about 3,200 km2. Historically, the San Bernardino kangaroo rat occupied alluvial floodplains and adjacent upland habitats within the San Bernardino, Menifee, and San Jacinto Valleys of San Bernardino and Riverside Counties in California, USA.

USFWS (2020a) identifies three separate remaining San Bernardino kangaroo rat populations: the Santa Ana River and tributaries, San Bernardino County; Lytle and Cajon Creeks, San Bernardino County, and the San Jacinto River, Riverside County. A fourth population identified by USFWS (2009) in the Etiwanda Fan and Wash in Riverside County is now extirpated (USFWS 2020a).

Habitat loss remains the primary factor threatening San Bernardino kangaroo rat populations. While there has been significant protection efforts within the remaining conservation units, habitat is still being lost to urbanization and conversion to agricultural uses (including water management). In some locations predation by feral cats is an additional threat (USFWS 2020a). Conclusive evidence of loss of genetic diversity and in-breeding points to populations that are highly vulnerable to stochastic events (e.g., flooding) which could result in extirpation of one or more remaining San Bernardino kangaroo rat populations. It is also highly susceptible to the effects of climate change through its dependence on natural flood plain processes that are compromised by water management activities and will be exacerbated by more infrequent precipitation and frequent droughts. Habitat loss reduces available remaining habitat which, in turn, reduces overall population size of already critically low San Bernardino kangaroo rat populations. Fragmentation of remaining habitat further separates remaining populations preventing the genetic exchange and dispersal necessary to maintain viable populations. Conclusive evidence of loss of genetic diversity and in-breeding points to populations that are highly vulnerable to stochastic events (e.g., flooding) which could result in extirpation of one or more remaining San Bernardino kangaroo rat populations.