SEDL / STP / STP817-EB / STP30186S

Plot Occupancy for Indicating Pocket Gopher Abundance and Conifer Damage

Anthony, RM
Zoologist and wildlife biologist, U.S. Fish and Wildlife Service, Denver Wildlife Research Center Field Station, Bend, Ore.

Barnes, VG
Zoologist and wildlife biologist, U.S. Fish and Wildlife Service, Denver Wildlife Research Center Field Station, Bend, Ore.

Pages: 9    Published: Jan 1983

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Abstract

Pocket gopher (Thomomys mazama) sign (mounds and earth plugs) was inventoried at 48-h and one-month intervals in study areas in central and south-central Oregon. Similar counts of 48-h and three-month accumulations of sign made by T. mazama and T. talpoides were taken in California, Idaho, and Oregon. Plot occupancy—the frequency at which sign occurred on circular, 81-m² plots—was strongly correlated with counts of individual signs and gopher depredation of planted conifer seedlings. For one area, we also determined that plot occupancy was significantly related to gopher density. We recommend the 48-h plot occupancy count—done in late summer or early fall, when gophers are most actively producing mounds—as the most useful index for forest management.