SALT-MARSH HARVEST MOUSE Reithrodontomys raviventris 



Order: RODENTIA Family: CRICETIDAE 



Distinguishing characteristics : External measurements: 135-162; 64-88, 16-19. Upper 

 parts pinkish cinnamon interspersed with black hairs, especially middorsally; under- 

 parts pinkish cinnamon or whitish; hind feet dark brown or whitish; tail dark brown or 

 blackish above, paler, sometimes almost white, below. As compared with R. megalotis 

 longicaudus , its geographically nearest congener, R. raviventris differs cranially in 

 larger skull with relatively shorter rostrum; nasals and incisive foramina shorter; and 

 zygomata more widely spreading anteriorly . 



This unusually dark-colored harvest mouse lives in the salt marshes where the ground 

 is damp or wet and the marsh plants form a thick mat over a network of interstices. 



Present distribution : Restricted to salt marshes bordering San Francisco, San Pablo 

 and Suisun Bays in areas where the salt marshes are not heavily diked on the upland 

 side. The remaining marshes with moderate populations include those near Petaluma, 

 San Pablo Bay near Vallejo, Grizzly Island in Suisun Bay, Point San Pedro, Dumbarton 

 in South San Francisco Bay, Alviso and the Palo Alto-Redwood City marshes of the 

 South San Francisco Bay. 



Former distribution : Extensive marshes bordering the San Francisco, San Pablo and 

 Suisun Bays . Especially prevalent throughout the Petaluma-Napa areas as well as the 

 Gallinas, Corte Madera and Petaluma Creek areas of the San Pablo Bay. The marshes 

 on both north and south shores of the Suisun Bay and most of the South San Francisco 

 Bay, especially in the extensive marshes which extended from the present city of 

 Oakland around the bay up to the areas now known as San Mateo and Burlingame. 



Status : Population low, natural range greatly restricted, once continuous distribution 

 now broken up into small isolated populations, destruction of remaining suitable habitats 

 has been accelerated over the last two decades . 



Reasons for decline : Most of its habitat destroyed by urban and industrial land fills and 

 salt production ponds . 



Protective measures already taken : Taking and possession prohibited by State law. 

 Establishment of South San Francisco Bay National Wildlife Refuge and acquisition of 

 Tubbs Island by The Nature Conservancy. 



Measures proposed : Continue with acquisition of key areas already started. 



Number in captivity : Few animals occasionally held for study in the Museum of 

 Vertebrate Zoology, University of California, Berkeley, and the Department of Biological 

 Sciences, San Jose State College, San Jose, California. 



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