Koford 77 Cynomys ludovicianus March 19, 1955 NW Weld Co., Colo. About 2 p.m., visited Dec. 22 colony & saw several out near my traps, but none in a bait cage (release not used or mice set bait?). Overcast but no wind. Pocket gopher & Dipodomys scratchings in a sandy hill at W. end of colony, March 20—snowed about 3". March 21, 1955 Boulder, Colo. Paul Morlin of Biology Dept. has had some experience in collecting rattlesnakes in C.L. towns. He said that the snakes wintered in unoccupied burrows, going in in October and emerging in mid-May. For a few days at these times a man had to be very careful in walking around in a colony. Sometimes about 7 snakes came out of one burrow & rested on mound or in entrance. He thought the prairie rattlesnake too small to feed on C.L., so probably not a major predator. Morlin said they used to be a large colony 3 mi. SW of Ft. Collins & another 20 mi. NW of Greeley. He also told me of an M.A. thesis at Colo. Univ. written by a student named D. O'Dell. This had some information on predation on C.L. by eagles. Another student named Ronald Smith was going to work on prairie dog ecology & had done some work in Nebraska. Formerly there were dog towns near Boulder but now few dogs left because of poisoning. A salamander Ambystoma tigrinum was sometimes found in C.L. burrows (check if actually seen). Morlin also said active burrows could sometimes be identified by fact that flies entered, presumably to lay eggs. March 22, 1955. Denver, Colo. Charles Sperry says that Salala does not grow in C.L. towns, but only around them; apparently they keep this weed down. Charles Harrison, an amateur snake man, told me that about 1947 in a dog town NE of Platteville he collected 65 Oritylus in on