Not knowing much about what small mammals are present in Fish Slough, I set out some Sherman live traps to see what I could get. It has been demonstrated that 84% of the species present in an area can be captured over the first three trap nights, but a fourth night only increases the estimate by 2%, so I left the traps out for three nights and two days. Since the weather isn't very hot during the day this time of year, I left the traps open during the days as well as nights. The traps were baited with peanut butter and oats and cotton balls were provided for bedding.
I ended up capturing 10 individuals of 4 species:
Sorex vagrans (vagrant shrew, 2),
Microtus montanus (montane vole, 1),
Reithrodontomys megalotis (western harvest mouse, 3), and
Peromyscus maniculatus (deer mouse, 4). Not a bad selection for the middle of winter! The shrews were a particular surprise, since they're not often captured in box-style traps.
 Sherman trap |
 Sorex vagrans |
 Microtus montanus |  Reithrodontomys megalotis |
 Peromyscus maniculatus |  cute mousey face |