Hooper, 1937 1 mi. W Avon (salt marsh), Contra Costa Co., Calif. Feb. 28, at least 4 marsh hawks were seen. A ground squirrel burrow was noted along the railroad embank- ment. Marsh wren, song sparrows, meadowlarks, Brewer Blackbirds were abundant, all "singing" in the evening and morning. I set out 35 "Benson" live traps and 67 snap traps at an averagedist. of 10 paces apart in the Salicornia and along the border of a stand of Baccharis (with Salicornia immediately adjoining). In Typha and along a slough bank 13 snap traps were set at an av. dist. of 8 paces. All were baited with oatmeal. Found this morning: In live traps: 1 Mus musculus. In snap traps placed in Salicornia: 9 Neithrodonmys, 1 Sorex, 2 Microtus, 2 Mus musculus. In snap traps in Typha: 2 Microtus. All but 2 house mice are saved as specimens. We ate dinner in Martinez, drove back to the marshes to spend the night. After collecting our traps this morning we drove back to Berkeley - reached here about at 10 A.M.