Reproductive characteristics of Northern Pocket Gophers, Thomomys talpoides, in Alberta alfalfa fields

The productivity of Northern Pocket Gopher (Thomomys talpoides) females inhabiting eight alfalfa (Medicago spp.) fields in Alberta was investigated in 1994. Breeding began in late March and was virtually complete by the end of May. A total of 131 pregnant females were captured on all study sites. Females had, on average, 6.1 (standard deviation: 1.4) viable embryos. There were 295 females with placental scars. They had, on average, 5.5 (1.4) scars. In some study sites, the mean number of embryos/female differed from the mean number of placental scars. In a comparison of various Northern Pocket Gopher populations, it is recommended to use mean productivity levels obtained with the same technique, i.e., embryo or placental scar counts.