Dibble, D.O 1989 Peromyscus californicus 19 Hastings Reservation, Monterey Co., Calif. April 8 at at 10,16.-Left him in trap for possible collaring waitana. Radio-collared M 040, 37g, Ch 1lo, and his mate F 1460, 43.5g lactating, Ch #7. Both animals were caught at 9,17. Dusted F 1460 with GREEN before release 0800h - on SPEED MC, we radio-collared M 1212, ch 10 at station 10,6; and his mate F 020, 43g, lactating strong, Ch 4 at station 11,5. F David also got locations on M 040, F 1460 together in fallen, rotting Oak log, ~2m long by 0.5m, at ~9.2,17. Earlier this am (0700h) David located F 1225, M 0130 in the at 0200h same rotting location as before (5.2,10). It looked good for fiber- optics, so we blocked two entrances with rocks or logs to return later this am! Evac. 1000h - returned to F1225's nest site with Mark Stanbach to help drill holes, etc. We thought we would have to block them proximally (base of tree) from escaping, but Mark's cuts revealed the trunk was solid. We blocked 2 escape (entrance) holes at the distal end with screen (see diagram below), and then we were able to cut out a hole with a pocket-knife (wood soft and rotting) about 10cm on the proximal side of their radio-locations. Inserted the fiber-optics and got a quick glimpse of a mouse, but they lit?) quickly moved distally. We then pulled out much of the litter and nest material for a better view, but not much better. We then blocked this hole to prevent them from going proximally past and covered the hole. Next we cut out another hole on the distal side of their location and got some good views of both adults and at least one suckling baby. The F escaped past this hole and we prodded her back between the 2 holes and blocked the tunnel leads south,