Date of this Version
Throughout the history of agriculture, man has competed with various animal species for the fruits of his labors. During the past 60 years, many research papers have dealt with the impact of field rodents and lagomorphs on agriculture. Damage has been estimated in various ways, from dollar values to cattle unit losses. In an early study, Shaw (1921) attempted to measure the amount of winter wheat loss due to Columbia ground squirrel. Grinnel and Dixon (1918) related ground squirrel damage to forage loss and cattle production. Several rodent enclosure and exclosure studies have been conducted in an attempt to measure the impact of field rodents and rabbits. Most of the damage assessment investigations involved rangeland production. The species studied have included prairie dogs (Taylor 1924, 1930; Fitch 1947), ground squirrels (Taylor 1930, Fitch 1947, Kalmbach 1948, Fitch and Bentley 1949, Norris 1950, Howard et al. 1950), jack rabbits (Taylor 1930, Kalmbach 1948, Norris 1950), kangaroo rats (Kalmbach 1948, Reynolds and Glendening 1949, Fitch and Bentley 1949, Reynolds 1950, Norris 1950), and pocket gophers (Kalmbach 1948, Fitch and Bentley 1949). Relatively few rodent damage assessment studies on agronomic crops, such as grain, alfalfa, and irrigated pasture, have been conducted in the western U.S. Foster (1965) noted that a large overwintering population of Microtus severely reduced production of irrigated wheat grass in seed fields and plots. The Belding ground squirrel (S. beldingi) is found in rangeland, pasture, and various agronomic crops. However, its impact on agricultural production ahs been measured only rarely, e.g., by Grinnel and Dixon (1918) and Sauer (1976, 1977). In California the effects of the Belding ground squirrel appear to be most sever in alfalfa. The present investigations were conducted to measure the impact of the Belding ground squirrel on alfalfa production in northeastern California.