The salt marsh harvest mouse (Reithrodontomys raviventris, SMHM) is an endangered rodent, endemic to the marshes of the San Francisco Bay Estuary (SFE), and comprises two subspecies, the northern (R. r. halicoetes) and the southern (R. r. raviventris). The northern subspecies is found in the brackish to saline marshes of San Pablo and Suisun Bays at relatively high numbers, while the southern subspecies occurs in the salt marshes of central and South San Francisco Bay , where populations are much smaller. The SMHM is adapted to its marsh habitat, but reliance on the marshes of the SFE has made this species vulnerable, as 90% of tidal marshes in the SFE have been lost to filling and diking. The Suisun Marsh represents about 10% of the remaining wetland habitat in California, but is primarily made up of wetlands managed for waterfowl, which have been considered inferior habitat for SMHM when compared to natural tidal wetlands. Nonetheless, large populations of SMHM occur on managed wetlands, and I sought to investigate the relative value of these two wetland types for SMHM through investigations of demography and populations (utilizing live mark-recapture methods), diet preferences (utilizing a cafeteria trial), and habitat use (utilizing trapping and radiotelemetry). Results of capture-mark-recapture analyses of trapping data revealed that wetland type alone did not have a significant effect on important demographic parameters for SMHM, or on abundance estimates, indicating that both wetland types support SMHM equally well. Results of the cafeteria trial revealed that, contrary to popular belief, pickleweed (Salicornia spp.) may not be the top preferred food choice of SMHM, as they spent significantly more time in the trials eating plants that are non-native and are grown extensively in managed wetlands as food for ducks. Finally, analysis of capture and telemetry data revealed that SMHM utilize many microhabitats within both wetland types, and that home range size does not differ between wetland type. Overall, the results of these projects indicate that managed wetlands provide substantial habitat value for SMHM, potentially equal to that of their natural tidal wetland habitat.
|Advisor:||Kelt, Douglas A.|
|Commitee:||Van Vuren, Dirk H., Eadie, John M.|
|School:||University of California, Davis|
|School Location:||United States -- California|
|Source:||DAI-B 81/1(E), Dissertation Abstracts International|
|Subjects:||Wildlife Management, Wildlife Conservation, Ecology|
|Keywords:||Managed wetlands, Salt marsh harvest mouse, San Francisco Estuary, Suisun Marsh, Wildlife conservation, Wildlife management|
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