Recreation, reconciliation and resilience: Conservation of an endangered rodent found only in one of the world's most degraded estuaries

Background/Question/Methods

Reithrodontomys raviventris), is endemic to the San Francisco Bay Estuary and is the only species of mammal entirely restricted to coastal marshes. While still adapted for life balanced between aquatic and terrestrial habitat, they are less equipped for this lifestyle than many of their estuarine neighbors. Up to 90% of the historical tidal marsh habitat of SMHM has been lost, and a large proportion of remaining wildlife habitat is privately owned and managed for waterfowl hunting. Optimal waterfowl habitat differs substantially from habitat historically believed to be favored by SMHM, however, and concerns that waterfowl management could be detrimental to this species have placed private resource consumers and public resource managers at odds for decades. To improve SMHM conservation and multispecies management, I investigated the relative habitat values of tidal wetlands and wetlands managed for waterfowl for SMHM. Over a three year period I surveyed SMHM monthly in paired tidal and managed wetlands to evaluate potential differences in populations across wetland types. On a seasonal basis at the same sites, I performed radiotelemetry and cafeteria trials to evaluate differences in habitat and food use, and availability.

Results/Conclusions

Results indicate that the historic tidal habitat of SMHM is not significantly superior to wetlands managed for waterfowl. Populations of SMHM were larger in tidal wetlands at some sites and larger in managed wetlands at others, indicating that wetland type alone did not affect population size. Radiocollared individuals utilized almost all microhabitats within, and regularly moved between wetland types. Further, preliminary analyses suggest that home range sizes are smaller in managed wetlands, indicating this habitat type may provide superior value. Finally, individuals in my diet study ate a wide variety of plant and invertebrate species, and more strongly favored plants grown for waterfowl than their assumed obligate food source, perennial pickleweed (Salicornia pacifica). The results of this study show that despite having quite different lifestyles, SMHM and waterfowl both benefit from waterfowl management. This opens the door to significant improvements in multispecies management as well as a better overall understanding of this important ecosystem. It also shows that focusing on the biology of endangered species without considering their overall ecology may leave managers lacking tools to conserve biodiversity in increasingly threatened ecosystems worldwide.