Ground squirrels also areknown to predate waterbird nests. In addition, because ground squirrels preferopen areas, well-vegetated levees and dikes will greatly deter their presence. All bats that occur in the Valley are insectivorous andrequire some form of water which they use as foraging sites and sources ofdrinking water. Bats occur among a wide variety of wetland habitat typesincluding riparian, permanent and semi-permanent marsh, and seasonal wetlands. In autumn, many bats migrate to warmer climates of favorable areas tohibernate.
Bats require two different roost types, day and night.
Because roosts are required features of bat habitat,they are often a limiting factor of bat distribution. Bats will roost incaves, trees, under tree bark, and in buildings. Because of their over-waterforaging, role as insect predators, and importance of adequate roost sites,wetland management can play an important role in the ecology of many batspecies. The most numerous small mammal species which use Central Valley wetlandsprobably would be the California vole, deer mouse, and western harvest mouse,with shrews occurring in lesser numbers. The introduced house mouse also occursregularly throughout the Central Valley's wetlands.