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Jennings and Haye- Species of Special Concern 96 California tiger salamanders, garter snakes, great blue herons, and raccoons are probably the most important predators of larval and post-metamorphic S. hammondii (Childs 1953, Feaver 1971). No data are available on the movement ecology or colonization abilities of S. hammondii. Habitat: Western spadefoots require temporary rainpools with water temperatures of >_ 9°C and < 30°C (Brown 1966, 1967) in which to reproduce and that last>_ 3 weeks (Feaver 1971) in order to metamorphose successfully. Rainpools in which western spadefoots reproduce and from which they are able to metamorphose successfully lack fishes, bullfrogs, and crayfishes; many indications exist that S. hammondii cannot recruit successfully in the presence of exotic predators, primarily introduced fishes, but also bullfrogs and crayfishes (K. Baldwin, S. Morey, B. Shaffer, pers. comm.; pers. observ.). Soil characteristics of burrow refuge sites that western spadefoots use have not been studied, but if they are similar to those of S. multiplicatrls, the soil may become fairly compact and hard during the season of summer aestivation (Ruibal et al. 1969). Status: Threatened; concern over the decline of S. hammondii is not new. Nearly 20 years ago, both Robert L. Livezey and Rudolfo Ruibal (in litt. 3 and 7 February 1972 to Leonard Fisk) believed that this taxon had sustained drastic reductions over the previous 15-20 years in the Central Valley and southern California. Current data indicate that in southern California (from the Santa Clara River Valley,Los Angeles and Ventura counties, southward), > 80% of habitat once known to be occupied by S. hammondii has been developed or converted to uses that are undoubtedly incompatible with its successful reproduction and recruitment. In northern and central California, loss of habitat has been less severe, but nevertheless significant; it is estimated that>30% of the habitat once known to be occupied by S. hammondii has been developed or converted to uses incompatible with the survival of this taxon: Regions severely affected include the lower two-thirds of the Salinas River system, and much of the areas east of Sacramento, Fresno, and Bakersfield. Moreover, in many ares of the Central Valley,remaining suitable rainpool or vernal pool habitat, which is concentrated on valley terraces along the edges of the Valley Floor,has been disappearing in a fragmented fashion, which may present a significant threat to the metapopulation structure of S.hammondii. The continued placement of mosquitofish by mosquito abatement programs in vernal pools threatens some populations (S. Morey, pers. comm.; pers. observ.). Emigration of juvenile and adult bullfrogs into rainpool breeding sites may also pose a threat to some populations (Hayes and Warner 1985; Morey and Gullin 1992; A. McCready and S. Morey, pers. comm.). Management Recommendations: Effort should be made to protect significant areas of rainpool habitat from alteration. Currently,rainpool habitats that harbor S. hammondii are protected in only a handfull of relatively small preserves,mostly under the jurisdiction of The Nature Conservancy (e.g., Santa Rosa Plateau,Riverside County; Pixley Vernal Pools Preserve, Tulare County). The biggest gap in current understanding of S. hammondii relates to its population structure and how habitat fragmentation may affect its likely metapopulation structure. Such an understanding is critical to determining the spatial population array that will allow S. hmnmondii to survive long-term. Much of the basic life history of S. hammondii remains poorly understood. In particular, variation in postmetamorphic survivorship, longevity, and movements must be understood in order to refine the direction of management. Finally, the features of suitable habitat remain poorly understood. It has often been assumed that S. hammondii requires loose soil for subterranean dormancy, but it has also been observed to occupy small mammal burrows (Stebbins 1951). Whether it uses the latter only as temporary refuges during its season of surface activity is unknown, but a better understanding of its pattern of utilization of subterranean refuges will allow refining of our current understanding of suitable habitat. Indications exist that western spadefoots can easily burrow into moist soils that would be