483 - 
INTRODUCTION 
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Effects on soil properties are varied. Gophers promote vertical 
cycling and mixing of soil constituents through continuous earth moving activities. 
The subsurface burrows tend to increase aeration and water movement within the 
soil, but also may aggravate drought conditions due to extended aeration of the 
soil (Hansen and Morris, 1968). Soil disturbance by gophers may also promote 
increased soil erosion, especially if soil pushed to the surface is deposited 
in natural drainage channels (Turner, 1973). However, Ellison (1946), although 
conceding that gophers were agents in soil erosion, concluded that gully cutting 
runoff could not be attributed to gopher activities. Soil fertility and friability 
are probably increased due to decay of buried plant material and the loosening 
of soil (Turner, 1969; Ellison, 1946). 
In addition to their beneficial and deleterious effects on vegetation 
and soil, gophers are a part of the food-chain of those systems. They are preyed 
upon by many mammals, birds, and reptiles, (Reid, 1973). 
Northern pocket gophers may need to be controlled, depending on 
management objectives of specific areas. The time for control depends on 
population size, which has traditionally been determined by ground survey 
techniques. These techniques have been based on trapping and sign-counting 
(Reid, 1973). The sign-counting technique developed by Reid et al. (1966) 
appears most appropriate since the gophers are not eliminated from the population, 
nor is the sample site disturbed by digging to set traps in the burrow system. 
This technique is based on the number of fresh mounds and earth plugs made’ in 
a 48-hour period in the early fall when the young-of-the-year, and older components 
Northern pocket gophers ( Thomomys talpoides Richardson) are small 
burrowing mammals (Fig. 1) inhabiting most montane and subalpine grasslands and 
meadows in west-central North America. In general, they range between 98° and 120° 
west longitude and between 36° and 52° north latitude (Fig. 2). In the northern 
part of their range, they may also be found in lowlands away from the mountains. 
The ecological and economic significance of northern pocket gopher 
populations has been intensively investigated because of their effects on 
vegetation and soils. The gophers tend to colonize an area that changes little 
in size regardless of animal population density. However, the effects on the 
habitat occupied varies dramatically as populations vary. Many factors, including 
depth of snowpack, of melt rate of the snowpack, and the availability of food have an 
influence on the populations. It is believed that population fluctuations vary 
randomly due the these effects (Reid, 1974). 
A detailed treatise on pocket gophers and mountain rangeland (Turner 
et al., 1973) leaves little doubt that northern pocket gophers significantly 
influence the amount and availability of herbage used by domestic livestock 
or other herbivores. During times of high populations, they may reduce herbage 
yields 20 percent or more. Their foods are primarily herbaceous species, 
although they do consume some shrubs and tree seedlings. Burrow building contributes 
to herbage losses by covering of plant material with soil.