by the male around the burrow of the female. 

 Receptive females emerge and copulation quickly 

 commences in the vicinity of her burrow. Com- 

 peting males interact, including bouts of locked 

 fighting, near the female's burrow (Kenagy 1976). 



OTHER CRITICAL ENVIRONMENTAL 

 REQUIREMENTS 



The population density of other species of 

 kangaroo rats has been shown to be inversely 

 related to the density of shrubby vegetation 

 (Rosenzweig 1973). This relationship reflects the 

 requirements of saltatory locomotion and the 

 erratic-leaping type of escape behavior that is 

 highly developed in kangaroo rats. Kenagy (1976) 

 suggests the leaping behavior may also function in 

 reducing male-to-male physical contact during 

 conflicts over access to females' burrows. Stewart 

 and Roest (1960) report the invasion of a burned 

 area by the Morro Bay kangaroo rat. Evidence 

 indicates that open, sparsely vegetated habitat is a 

 critical requirement for populations of this 

 kangaroo rat. 



POPULATION NUMBERS AND TRENDS 



The population of this subspecies is directly 

 related to both the quality and quantity of avail- 

 able habitat. The range was originally described 

 by Grinnell (1922) as "less than 4 miles square" 

 (41 km^ ). Stewart and Roest (1960) reported the 

 area of remaining habitat to be less than 6.5 km^ . 

 In 1960, the population numbered about 8,000 

 individuals (Congdon and Roest 1975). A 1971 

 study indicated a range of 3.6 km^ and a popu- 

 lation of 3,000 kangaroo rats Congdon 1971, in 

 Congdon and Roest 1975). Roest (1977) indi- 

 cated that the range is now reduced to 1.3 km^ 

 and the population numbers are between 1,500 

 and 2,000 individuals. 



The density varies from 42 kangaroo rats per 

 hectare in the most favorable habitat to an esti- 

 mated 5 per hectare in marginal habitat. Territory 

 size is estimated to be about 0.07 ha (Roest 

 1977). Roest (1977) indicates considerable sea- 

 sonality in their activity, with little or no activity 

 in January and February, and increasing activity 

 through early summer. A decline in activity was 

 noted in mid-summer, and a fall resurgence is 

 suggested. 



REPRODUCTION 



Most young are probably born from February 

 through August, but breeding may continue 

 throughout the year with a possible second peak 

 of breeding in the fall (Roest 1977). A similar 

 concentration of breeding in the spring and 

 summer months occurs in D. h. tularensis, which 

 also may have multiple litters per year (Fitch 

 1946). Average litter size is probably just over 

 three. Four recorded litters for the Morro Bay 

 subspecies were 4, 3, 3, and 3 (Stewart and Roest 

 1960). Other subspecies of D. heermanni are 

 reported to have average litter sizes of 2.6 to 3.7 

 (Fitch 1946). 



MANAGEMENT AND CONSERVATION 



A summary of management problems for this 

 subspecies is presented in Congdon and Roest 

 (1975). The most significant adverse factor is the 

 loss of habitat, caused by conversion of parts of 

 the former range into suburban housing develop- 

 ments. While kangaroo rats may be tolerant of the 

 proximity of human dwellings (Stewart and 

 Roest 1960), they are eliminated from developed 

 land. A concomitant problem is predation by do- 

 mestic cats near houses. A more serious problem 

 in remaining prime habitat is the absence of wild 

 fires, leading to higher shrub density and the 

 development of a mature chaparral community. 

 This subspecies may invade habitat created by 

 burning (Stewart and Roest 1960). It disappears 

 from fields as the shrub height and density in- 

 crease (Congdon and Roest 1975). Management 

 should thus be directed towards prevention of 

 further loss of habitat by a moratorium on devel- 

 opment of any remaining Morro Bay kangaroo rat 

 habitat and maintenance of existing habitat in the 

 early stages of succession, which constitutes the 

 favored condition for this subspecies. Both these 

 management programs could be most easily 

 achieved within the confines of a publicly owned 

 preserve. Recently, a 20-ha refuge for this animal 

 was established by the California Department of 

 Fish and Game for the westernmost ('Dunes') 

 population (see range map)(Gustafson 1978). But 

 the habitat in this refuge contains the lowest 

 population density of Morro Bay kangaroo rats 

 measured by Roest (1977). Other areas of prime 

 habitat should be acquired. Areas of favorable 

 habitat which are used by off-road vehicles are 



