Koford, Rolf R. 1974 Journal 11 Dec. Arroyo Martinez mouth, Rancho La Burita, Baja California del Norte, Mexico ~10 ft. We picked up all the traps except for a few gopher sets. I caught 2 gophers from 6 sets, one at night, one during the day. No woodrats were caught in 3 non-folding tomahawks I set by apparent woodrat nests in the rocks. Four Peromyscus, two Dipodomys were cought in 20 large folding Shermand Larry and Dr. Lickicker set up the centrifuge and took plasma, hemolygth, and tissue (liver and kidney) samples from the animals while Pete and I put up the skins. Later Larry and Dr. Lidicker also put up a few skins. We did not finish processing all the material but had to leave for a rendevous with Bill Glanz, Dave Bradford, and Dave Krohe at 1400. We went through Tijuana, getting some money changed there, and onto the toll road. We exited at La Solina and met the others on the beach there, then went north on the *free road for several miles to a town just north of a wide (~1/2 mile) arroyo with salt marsh in the bottom. We camped near the north end on a road jutting into the marsh. We set out traps in lines. Dr. Lidicker and Pete found fresh Microtus sign about 1/4 mile east of our camping spot. Larry found old Microtus scats among the Salicornia. I found a hole about 3 cm. in diam. with a mound of dirt to the side and put a gopher trap in it. The sky was clear all day. Sunrise at ~0630, temp. 75° thm. Midday temp. in high 50's(°F); sunset ~1630. Wind 5-10 mph.