1936] MAMMALS OF OREGON 177 



Among the rocks the same building material is used to fill and block 

 the passages leading back to the nest cavities. The nests of soft plant 

 fibers are placed in cool, clean chambers deep underground or well 

 back in cavities among the rocks. They are always neat and clean, 

 and even those found on shelves or beams or under the floors of de- 

 serted buildings are as well made and uniform in design as many 

 birds' nests. 



One of the wood rats kept in captivity at Malheur Lake during 

 July and August was gentle in disposition, timid but not nervous, 

 and soon submitted to being stroked as it sat in its nest. It never 

 made any vocal sounds, but tapped with one hind foot on the boards 

 or in the nest with a soft thud, thud, thud, sometimes with one foot 

 and sometimes with the other. It would spend a large part of each 

 night running in its hollow wheel, but slept most of the daytime 

 curled up in its soft nest. On cold nights the nest was drawn up 

 around its neck or over the top of its head. 



Breeding habits. As in other species of wood rats, the mammae 

 are arranged in 2 pairs of inguinal, and the young are usually 2 to 

 4 in number, but there are several records of 5 embryos. The young 

 are born from February to May, and some as late as July, and in 

 some cases more than one litter may be raised in a year. 



Food habits. In the free wild state the food of these wood rats 

 consists of a great variety of green plants, fruit, seeds, and any 

 scattered grain that comes their way. The captive was a dainty 

 feeder, never eating much at a time and picking the choice bits, green 

 leaves, tender tips, and branches of plants. Pigweeds of 3 or 4 

 species were eaten, as also were Atriplex, Dondia, Sarcobatus, Poly- 

 gonumi, nettles, dock, grasses and grass seeds, cabbage, cantaloup, 

 apple parings, lettuce, green corn, rolled oats, bread, cheese, and many 

 of the scraps from the table. He would not eat meat, cooked or raw, 

 and did not kill the meadow mice or white-footed mice kept for 

 several days in his cage. 



Economic status. Over most of the range of this species the desert 

 valleys do not produce enough forage for stock, so the little green 

 vegetation eaten is of no importance. In only rare cases do the rats 

 come in contact with camps or ranches where some slight mischief 

 might be done, and here they are so easily controlled as to prove of 

 little economic importance. 



ONYCHOMYS LEUCOGASTER FUSCOGBISEUS ANTHONY 

 OREGON GRASSHOPPER MOUSE; BROWN SCORPION MOUSE 



Onychomys leucogaster fuscogriseus Anthony, Amer. Mus. Nat. Hist. Bull. 

 32: 11, 1913. 



Type. Collected at Ironside, Malheur County, Oreg., by H. E. Anthony in 1912. 



General characters. A sturdy little animal, with short, thick, tapering tail 

 (pi. 32, A) ; short legs; erect ears; and a keen, bold, almost weasellike, expres- 

 sion of face. Color: Upper parts of adults, dark reddish brown with dusky 

 along middle of back and on face and ears and top of tail ; whole lower parts, 

 feet, lower half and tip of tail, nose, and tuft at anterior base of each ear 

 snow white. Immature specimens with slaty gray or plumbeous upper parts. 

 The darkest specimens are from the Klamath region. 



Measurements. Average of several adults: Total length, 143 mm; tail, 38; 

 foot, 19.2; ear (dry), 15. Of large female: 150; 40; 21; 16. Weight of appar- 

 ent subadult male when captured, 22 g ; after 2 years of captivity, 45.5 g. 

 7209 < 



