Description
A long-tailed shrew with a grayish brown dorsum (to nearly black in subspecies SINUOSUS) and smoky gray venter (to dark brown/blackish in SINUOSUS); third unicuspid smaller than the fourth; tail not sharply bicolored; underparts paler than upperparts; nose pointed; eyes small and inconspicuous; adult total length 80-110 mm, tail 28-46 mm, hind foot 9-14 mm, mass 2.9-8.7 g; condylobasal length 14.7-17.1 mm; foramen magnum relatively high in the occiput (Ingles 1965, Hall 1981, Owen and Hoffman 1983).
Diagnostic Characteristics
Differs from S. TROWBRIDGII in having the underparts paler than the upperparts (rather than the same darkness) and the tail not sharply bicolored. Differs from S. VAGRANS in having the foramen magnum placed relatively dorsally (rather than encroaching less into the supraoccipital and more into the basioccipital (see Ingles 1965:93). Differs from S. TENELLUS in larger condylobasal length (more than 15.8 mm vs. less than 15.8 mm). Differs from other species in the subgenus OTIOSOREX by the following combination of characters: upper third unicuspid tooth smaller than the fourth; condylobasal length of skull 14.7-17.1 mm; medial tine of upper first incisor tooth contained entirely within pigmented area; upper toothrow not crowded, with distinct triangular space between postero-medial edge of the fifth unicuspid and antero-medial edge of premolar (Owen and Hoffman 1983). See Carraway (1995) for a key to western North American soricids based primarily on dentaries.
Habitat
Marshes, salt and fresh; low, dense vegetation adjacent to rivers, lakes, and streams; grassy hillsides and chaparral slopes; occasionally into adjacent woodlands (Hoffman, in Wilson and Ruff 1999). May use burrows of other animals.
Ecology
Typical maximum life span is 12-16 months.
Reproduction
Throughout the range, reproduction is known to occur from late February to early October.