or low trees. They travel in runways of their own, and also in those 

 made by other mice, and are out both by day and night. The food is 

 mainly seeds and grain, with some green vegetation. The young are four 

 or more in number, and they appear to breed throughout spring and 

 summer into the fall. 



Gary noted one at Wray moving about in the brush and often winding 

 its tail around a twig to assist itself. The writer found one at Barr under 

 an old piece of sheet iron lying on the prairie. 



The colors of the various forms in Colorado vary from light buff to 

 various shades of brown, usually light, but often, if not always, mixed with 

 blackish hairs. The tail is bicolor, brown above, lighter or white below. 

 Adults vary in length from 4.8 to 5.95 inches, and the tail from 2 to 2.5 

 inches. 



The Harvest Mice occurring in Colorado are the Pallid Harvest Mouse, 

 Rheithrodontoinys albescens albescens; the San Luis Valley or Mountain 

 Harvest Mouse, R. moiitanus; the Aztec Harvest Mouse, Rheithrodontoinys 

 megalotis azteciis; and the Prairie or Nebraska Harvest Mouse, R. m. 

 dychei. 



The Mountain Harvest Mouse is interesting from the fact that the 

 first specimen was taken by one of the Pacific Railroad surveying parties 

 in August, 1853, and was described by Baird in 1855. The type specimen 

 long remained unique. A single immature specimen was taken by Vernon 

 Bailey at Del Norte in 1904. In the fall of 1907 Merritt Gary went to the 

 Medano Ranch, 15 miles northeast of Mosca, probably not far from the 

 place at which the type was taken, and collected a considerable series of the 

 animals, enabling a detailed study to be made for the first time. He found 

 them on a low sandy ridge running through the meadows on the ranch, 

 The present writer was unable to secure any at the same place two years 

 later, but did take one at Crestone, several miles farther north. 



As a whole the distribution of Harvest Mice in Colorado is not 

 very well known. They seem to be quite common in northeastern Colorado, 

 have been taken at Canon City, and are also found in various portions of 

 southwestern Colorado. I have not found them at Colorado Springs, nor 

 did I take any in southeastern Colorado in 1905. 



DEER MICE OR WHITE-FOOTED MICE. 



Of our native wild mice probably the best known to outers are those 

 belonging to the group collectively known as Deer Mice or White-footed 

 Mice, the former name being derived from the tawny color of many of the 

 species, something like that of the red coat of a deer, and the latter from 

 the fact that most of them have white feet. They are members of the 

 genus Peromyscus, a very large group which has been subdivided into 

 several subgenera. In Colorado we have no less than eight species and 

 subspecies. 



There is more or less similarity in the habits of all these. They are 

 strictly nocturnal. It would be difficult to find a locality or situation 

 which was not inhabited by one or more species. In certain portions of 

 Colorado I have found four species in the same locality. They are sure 

 to be found about rocks, and dead logs and brush. The banks of the dry 

 arroyos of the prairies often have holes inhabited by these mice. Traps 

 set in meadow mice runways in wet grassy places usually yield their quota 

 of deer mice. In short, they are practically everywhere. In altitude they 

 range from the lowest elevations up to timberline at least. Osgood says: 

 "Throughout practically all of the western United States they exist in 

 countless numbers, perhaps exceeding those of the other combined mam- 

 malian inhabitants of the region." 



Usually, so far as my observations go, living in holes in the ground 



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