Influence of Range Seeding on Rodent Populations in the Interior of British Columbia

Abstract

This study was designed to determine the influence of range seeding on rodent populations inhabiting cutover lodgepole pine forest land in the interior of British Columbia, Canada. Both deer mice and voles were strongly attracted to an area seeded with grass mixture in the early spring, even though overwinter mortality had dramatically reduced the average density to <2 animals/ha. Five rodents as well as several seed-eating birds appeared on this seeded area while no animals were recorded on a nearby control. Subsequent seeding experiments in the summer also produced significant increases (2 to 2.2 times) in rodent populations. Success of range seeding in B.C. can be quite variable, possibly due to seed predation by mice and voles. Consequently, both the quality and quantity of seed remaining for germination and forage production may be radically altered. Grass seeding of cutover forest land is designed to improve range conditions for cattle grazing in many parts of western Canada and the United States. These seedings are successful in some areas but do not produce the expected growth of forage in other localities. There are probably several factors responsible for this inconsistency, but one potential problem is rodent predation on the grass seed. Seed predation by the deer mouse (Peromyscus maniculatus) has contributed to the failure of several range seeding projects (Howard 1950, Casebeer 1954, Johnson 1961, Nord 1965, Nelson et al. 1970). Everett et al. (1978) have reviewed the range seed preferences of deer mice. Voles of the genus Microtus spp. also harvest large quantities of grass seed (Batzli and Pitelka 1970, Marshall and Jain 1970, Borchert and Jain 1978). These microtines usually inhabit grassland areas but may also occur on interior logged sites (Radvanyi 1973, Sullivan and Sullivan 1982). Little quantitative information is available on the response of rodent populations to range seedings. To determine the influence of range seeding on deer mice and voles and devise suitable control methodology for reduction of seed predation, a preliminary assessment of rodent populations is required. This study was designed to monitor rodent populations before and after grass seeding of cutover lodgepole pine (Pinus contorta) forest lands.