1936] MAMMALS OF OREGON 167 



General Tidbits. These large handsome flying squirrels live in both 

 the yellow pine timber, and higher up through the lodgepole pine 

 and spruce forests, always among the tall trees where they travel 

 through the air from trunk to trunk or come down the trunks to 

 gather food on the ground. They rarely get far from the trees, 

 which are their main protection from enemies. Even the marten, 

 which may follow them to the top of the tallest tree, is left behind as 

 they soar away to distant trunks. The type and two others were 

 caught in traps set for marten at the base of trees and baited with the 

 bodies of birds and small mammals that had been skinned for speci- 

 mens. The flying squirrels are always a great annoyance to trappers 

 as they are fond of meat and constantly get into marten traps. 

 They are rather omnivorous in taste and accept almost any camp 

 supplies, regularly visiting camp grounds for the scraps of food to 

 be found. At the type locality one stole a biscuit one night from the 

 grub box, and when Merriam fired into the treetop it dropped the 

 biscuit at his feet. The animals are fond of rolled oats, bread, nuts, 

 seeds, or any grain used as trap bait, and like other varieties of the 

 group probably eat many insects and insect larvae. 



Economic status. These forest dwellers rarely come about build- 

 ings or clearings and so are not likely to cause any loss of crops or 

 property. The suspicion that they rob birds' nests may have some 

 basis in fact but needs careful investigation before it can be accepted. 

 Also the extent and nature of their insect food should be given care- 

 ful study, as it would not be surprising to find that they contribute 

 much to the protection of the forests and to the control of insects. 



Family MURIDAE: Rats and Mice 



RATTUS NORVEGICUS (EEXLEBEN) 



NORWAY RAT ; BROWN RAT ; HOUSE RAT ; BARN RAT ; WHARF RAT ; SEWER RAT 



[Mu$~\ norvefficus Erxleben, Syst. Regni. Anim. v. 1, p. 381, 1777. 



Type locality. Norway. 



General characters. Large and heavy ; tail about as long as head and body, 

 tapering, annulated, scantily haired; ears medium large, nearly naked; soles 

 naked; pelage coarse and harsh. Color in adults, upper parts rusty gray, 

 lower parts soiled yellowish white or dirty gray. Young dusky gray above, 

 lighter gray below. 



Measurements. Good-sized adult male. Total length, 400 mm; tail, 200; 

 foot, 45; ear (dry), 18; from crown, 13. Weight 1 to 2 pounds, but very 

 large individuals weighing more than 2 pounds have been recorded. 



Distribution and habitat. Supposedly native of Asia, these rats 

 spread to Europe in 1730 to 1750, and to North America in 1775, 

 and are now found over much of the inhabited earth. 



They have kept close behind the vanguard of civilization in its 

 progress across the continent of North America and were probably 

 taken to Oregon on ships in the early part of the last century. A 

 specimen was collected at Astoria by Lieutenant Trowbridge in 

 1855 (Baird, 1857, p. IfiS} . At the present time they are common all 

 along the coast country of Oregon, throughout the Willamette Valley, 

 and in the Columbia River Valley. At Millers, near the mouth of the 

 Deschutes, Jewett reported them in 1915 as a serious pest in the grain 



