Reproduction and productivity of Shiras moose (Alces alces shirasi), based on macroscopic examination of 424 female reproductive tracts plus analysis of sex and age of 1,581 animals harvested in Montana in 1963 and 1965-1971, are reported. Forty-three and 92 percent of yearling and adult cows collected after 1 October had ovulated, respectively. Ovulation rates were 48 and 115 per 100 yearling and adult cows, respectively. Pregnancy rates were 32 and 86 percent for the same respective age groups. Yearling and adult twinning rates were 0 and 16 percent, respectively, with 32 and 100 calves per 100 cows for the same respective age groups. Yearlings were no more, or less vulnerable to hunters than adults. Gross productivity, net productivity and rate of increase were 25, 20, and 34 percent, respectively. Comparison of our data with that from several other regions indicates that Shiras moose in Montana are equally as productive as any other North American moose herds studied. Differences between in utero and post partum productivity are discussed.
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