endemic to a single state or province

United States

Origin: Native

Regularity: Regularly occurring

Currently: Present

Confidence: Confident

Type of Residency: Year-round

Global Range: (<100-250 square km (less than about 40-100 square miles)) Small area near Morro Bay, San Luis Obispo County, California.

Historic Range:
U.S.A. (CA)

Length: 29 cm

Type for Dipodomys heermanni morroensis
Collection: Smithsonian Institution, National Museum of Natural History, Department of Vertebrate Zoology, Division of Mammals
Sex/Stage: Female; Adult
Preparation: Skin; Skull
Collector(s): E. Nelson
Year Collected: 1891
Locality: Morro, [about 4 mi S (see Grinnell 1922)], San Luis Obispo County, California, United States, North America

Comments: Early seral stages of the chaparral community; low and sparse vegetation; widely-scattered shrubs; medium-textured sandy loam: southern coastal scrub, coastal sage scrub, or coastal sand plains and stabilized dunes. Plant species in habitat include bush lupine, dune lupine, mock heather, coyote bush, California sagebrush, croton, buckwheat, phlox, and deerweed; plant roots provide support for burrows (Matthews and Moseley 1990).

Non-Migrant: Yes. At least some populations of this species do not make significant seasonal migrations. Juvenile dispersal is not considered a migration.

Locally Migrant: No. No populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).

Locally Migrant: No. No populations of this species make annual migrations of over 200 km.

Note: For many non-migratory species, occurrences are roughly equivalent to populations.

Estimated Number of Occurrences: 1 - 5

Comments: In 1990, limited to two wild populations and one experimental population in an enclosure (California Department of Fish and Game 1990). Curuently known from one site comprising less than 200 acres (USFWS, Federal Register, 25 January 2000).

1 - 1000 individuals

Comments: 1500-2000 in 1977, down from 8000 in 1960. Historically, range was less than 10 sq km (Grinnel 1922); recent estimates show range of only 1.25 sq km, supporting a population of 330-1200 kangaroo rats (Tayoshima 1980). Total wild population in early 1990s was as low as 50 (California Department of Fish and Game 1990).

Population density varies widely with habitat. Density estimates varied from 42/ha in best habitat to 5/ha in marginal habitat. In one area, individual foraging range was estimated at 30-122 m across.

Comments: Little or no activity in January and February, increase in early summer, decline in mid-summer, possible fall resurgence. Generally emerges soon after dark. Rain and fog, and sometimes moonlight, may inhibit activity.

Breeding appears to begin simultaneously with plant growth in spring. Lifespan is probably 3 years (Matthews and Moseley 1990).

United States

Rounded National Status Rank: N1 - Critically Imperiled

Rounded Global Status Rank: T1 - Critically Imperiled

Reasons: Restricted habitat and narrow range in southern California; vulnerable to habitat loss from residential and agricultural development; extremely low population size.

Current Listing Status Summary

Status: Endangered
Date Listed: 10/13/1970
Lead Region:   California/Nevada Region (Region 8) 
Where Listed:


Population detail:

Population location: entire
Listing status: E

For most current information and documents related to the conservation status and management of Dipodomys heermanni morroensis , see its USFWS Species Profile

Global Short Term Trend: Decline of 50-70%

Comments: Declined significantly during the period 1982-1990 (USFWS 1990). See GABUNDCOM.

Degree of Threat: A : Very threatened throughout its range communities directly exploited or their composition and structure irreversibly threatened by man-made forces, including exotic species

Comments: Endangered because of due to human encroachment on habitat and lack of natural disturbance by fire (e.g., results in unsuitable vegetation density) and other factors (e.g. predation by cats) (Kelt 1988). Habitat fragmentation probably has had a negative impact.

Management Requirements: Periodic burning of the habitat to create open spaces may be needed. A draft revised recovery plan was available in January 2000 (U.S. Fish and Wildlife Service, Ventura, California; telephone 805-644-1766).

Biological Research Needs: Obtain additional information on ecology and life history. Develop captive breeding techniques.

Global Protection: Few (1-3) occurrences appropriately protected and managed

Comments: State purchased 20 ha in Pecho area near Morro Bay and adjacent to Montana de Oro State Park to establish the Morro Dunes Ecological Reserve (Matthews and Moseley 1990).

Needs: Protect all EOs. Would benefit from habitat manipulation to establish a less mature stage of vegetation and from acquisition of more habitat.