E. Heske 1982 Journal San Isidro, Puntarenas Prov., Costa Rica Aug. cont. and a field with some brush, bananas on the other side. Alt. 525 m. weather clear, sunny + hot. In an extensive area of moisten, more mature forest 18.4 km SW San Isidro , I set 60 more traps, Duke set 60 traps. The canopy here is higher and more dense, areas of thick herbaceous ground cover ~ .5-1 m tall, more vines, etc. Looks like better Heteromys habitat!. Both areas are fairly flat - a welcome change! Here I saw my first tierciopelo - just as I finished setting traps and began to leave the forest, it moved out of my way and stuck it's head up above the leafy ground cover to look at me. I was about 1.5m long (maybe a bit less, I couldn't see the whole snake) and the coloration looked like a rotting stick - very cryptic. We spent the night in San Isidro , which is a fairly pleasant place with a nice town square. Full moon. Warm clear evening. San Isidro to Cd. Neily, Puntarenas Prov., Costa Rica 5 Aug. Arose 0600 and went to check traps after first eating breakfast and checking out of our hotel. At the nearby site where we had 120 traps between us, I only caught 1 juvenile Heteromys , Duke caught 1 juvenile Heteromys and a Proechimys . The further site yielded some surprises. My line caught only 1 Proechimys and an Oryzomys -