Controlling field rodents in California (1953) (20505198479)

Muskrat
Title: Controlling field rodents in California
Identifier: controllingfield434stor (find matches)
Year: 1953 (1950s)
Authors: Storer, Tracy I. (Tracy Irwin), 1889-1973
Subjects: Mammals; Rodents
Publisher: (Berkeley, Calif. ) : Division of Agricultural Sciences, University of California
Contributing Library: University of California, Davis Libraries
Digitizing Sponsor: University of California, Davis Libraries



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with underwater entrances and sometimes construct small "houses" of plant mate- rials in quiet waters. Muskrats reached the Imperial Valley soon after completion of the canal carry- ing water from the Colorado River. In the 1930's muskrats escaped from fur farms or were transplanted and released in several localities from Del Norte and Shasta counties south to Santa Barbara and Kern counties (Storer, 1937; Twin- ing and Hensley, 1943). Today, in the coastal counties, they are present only in a few places and in small numbers, so that no damage has resulted. In the Sacramento Valley south to the Delta re- gion, however, and in parts of Modoc County, they have multiplied and spread to become a serious agricultural problem wherever irrigation waters are stored and used. The "rats" burrow commonly in dams and ditchbanks and about head- gates or outlet boxes, resulting in breaks in the earth banks with consequent loss of water. Farmers are experiencing in- creased trouble and expense to repair the damage and reduce the muskrats, besides suffering some loss in crops. A crude esti- mate of the annual expense in the Sac- ramento Valley is nearer $50,000 than $25,000. In addition, rice growers suffer premature drainage of producing fields by undetected leaks and breaks in ditch banks that result in lessened returns on the crop. In eastern states, where irrigation is unnecessary, the native muskrats do no particular damage to agriculture; but wherever irrigation or drainage is needed in the West, the animals can be a con- tinuing source of trouble. For almost a decade fur trappers have taken substantial numbers for pelts. In 1952 they captured about 70,000 which sold at 47 cents to $1.36 each, yielding about two-thirds the total fur income in California. Trappers naturally seek musk- rats where abundant and in winter when the fur is prime. How to trap. Where muskrats must be prevented from damaging irrigation structures, No 1 steel traps should be set in burrows, or better on the characteristic "feeding mounds" in water 2 to 3 inches in depth, and should be partly sunk in the bottom material. The trap chain
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Fig. 22. Muskrat. The tail is narrow, higher than wide, and scaly; the fur is soft, dense, and brownish. Head-and-body 9Vi to 12 inches, tail Th to 10 inches. 41