224 NORTH AMERICAN FAUNA [No. 55 



General characters. Relatively small; form slender; colors dull and pale; 

 upper parts rusty brown ; lower parts drab brown ; under fur uniformly pale 

 brown or drab; skull very long and narrow, with long slender rostrum and 

 narrow nasals ; dentition light. 



Measurements. Adult male from type locality : Total length, 1,046 mm ; tail, 

 254; foot, 183; ear (dry), 24. Weight not given. Young adult, a 1% -year-old 

 female (Oct. 11), from same place measured 946; 368; 190; 24 mm; and 

 weighed 32 pounds. 



Distribution omd habitat. In 1826 one of Ogden's beaver trappers, 

 Sylvailles by name, discovered the river flowing into Malheur Lake 

 from the north, since called Silvies River and reported it rich in 

 beavers. The following year the party again visited this river in 

 June, when they took 300 beavers in about a month, but complained 

 that the natives of this section had destroyed upwards of 6,000 beav- 

 ers, not 1 of which had reached their trading posts (1910, pp. 221). 

 In 1828 Ogden and his party of trappers struck south across Alvord 

 Valley onto the headwaters of streams flowing south, probably the 

 headwaters of Quinn River and the North Fork of the HumBoldt, 

 near the Nevada line, into country where " there were great numbers 

 of Indians and abundance of beavers." Here in November his 6 

 trappers brought in as high as 52, 58, and 60 beavers a day, and 

 before the month was over they had taken 800 skins. In April of 

 the following spring he returned to this " unknown river " with a 

 larger party to complete the fur harvest and on May 8 reported 

 1,700 beaver skins taken and said " in no part have I found beaver so 

 abundant ". 



These desert- valley beavers are still found in the Great Basin 

 drainage of northern Nevada along the Humboldt River, and its 

 tributaries and in the Malheur Lake and S teens Mountains drain- 

 age of southeastern Oregon (fig. 50). Two skulls from Fish Creek, 

 a branch of the Blitzen River, which flows into Malheur Lake from 

 the south, are typical ~boAleyi. There are a few beaver all along the 

 Blitzen from its headwaters down to near Malheur Lake, and George 

 Benson reports one shot at the edge of Malheur Lake in 1909. In 

 1916 they were found in Big Fish Creek, McCoy Creek, and Kiger 

 Creek. It is fair to assume in the absence of specimens that the 

 beaver in the Silvies River and its branches on the north of Malheur 

 Lake are also of this subspecies. In 1920 they were still common in 

 many places along the Silvies and Blitzen Rivers, and while in places 

 they were doing some damage by flooding the meadows, more often 

 they were merely holding up the water to a better depth and 

 improving the meadows by subirrigation. 



On the other hand they sometimes dam the irrigation ditches or 

 locate in the banks of streams near fields and orchards where they 

 do serious mischief and have to be removed, driven away, or de- 

 stroyed. With intelligent handling and the introduction of a darker 

 and more valuable fur variety they could become a valuable asset 

 on many of the eastern Oregon ranches. 



