J.R. Mcleorn 1940 Microtus Hmi W Fort Howe R.S., 4000ft, Powder River Co., Montana. June 14 Natural causes. I set 20 traps in these runs and this morning I found three Microtus in the traps. Nos 1714, 1715, 1716. On my way back to camp I noted in another area several runs which were apparently in use and as indicated by droppings & cut grass many Microtus were using these runs. This was in the bottom of a E running small canyon and the grass was shaded most of the day by the growth of conifer trees. It is rather a dry location and no water is within 150 yards of the runs. I am unable to explain why these mice apparently favor the dry grassey areas to the wet " " along the small stream. Traps which I set last night were baited with "chewed" rolled oats and set about 4 ft apart over an area of 40 feet square.