RIBBLE, D.O 1984 PEROMYSCUS CALIFORNIUS 4. Hastings Reservation, Monterey Co., Calif. Jan 26 (cont) This PM on GRID MC I caught ?#1480, imm, covered with RED powder at station 8,4 (confirming ?# 0100 as mother). Jan 27 This AM on GRID MC I redusted ?#020, lactating with PURPLE powder at st 10,4. At 0930h this am I weighed all the captive babies and then conducted "arena" a dyadic encounter experiment using the plexiglass tube (9in diameter) Bob Jones supplied I placed the arena in the right half of ?#1441's, ?#1410's enclosure. I first introduced ?#1412 (from the other enclosure) and he huddled against the side. I then introduced ?#1410 (resident) and both males began jumping around like they were trying to escape but then within ~5 sec ?#1412 jumped on 1410 and they proceeded to wrestle with 1410 on the bottom. Since this was so violent I immediately pulled the arena out and both mice retreated to opposite corners. I put ?#1412 back in his enclosure and noted his right front paw was bleeding from 2-3 small cuts (not badly, should be okay). Need to test the arena in the field, but this first test went as planned. This PM on GRID MC caught ?# 146b at 10,15 covered with fresh PURPLE powder (from ?? 020), and ?# 1212 is caught at 9,10 covered with fresh PURPLE powder (from ?? 020). After checking traps this PM I conducted a dyadic encounter between ?#?'s 14604 (visitor) and 1206 (home mouse) at station 7,4. Virtually nothing happened! Both mice stayed in the same position the entire time - huddled with head against side of enclosure. After 4 mins I put #14604 on top of 1206 to try to elicit some response - then they just huddled together! Data recorded on behavior data sheets.