Fertility of mule deer in Utah
Robinette, W.L.; Gashwiler, J.S.; Jones, D.A.; Crane, H.S.
Jour Wildlife Management 19(1): 115-136
1955
DOI: 10.2307/3797561Document Number: 394580
1000 pregnancy examinations of mule deer (Odocoileus h. hemionus) does were made. Ovulation rates (detd. by corpora lutea counts) increased with each of four age classes (1-year, 2-yr., 3-7, 8 and over). Percentage loss of ova increased with the number shed, however, being 50% for does shedding four as compared to 10% for those shedding two. Overall there were 89.5 fetuses surviving to mid-pregnancy for each 100 ova shed by does bred currently. Some evidence of identical twinning was obtained. A few cases of resorption and abortion of fetuses were noted. A total of 21 atrophic fetuses were found for 1263 embryos examined. Only 11 prenatal corpses could be sexed-6 males and 5 females. The sex ratio for 1169 fetuses was 111 males: 100 females. . Does older than fawns averaged about 1.5 fetuses-the exact rate appearing to vary with nutritional conditions. Summer and winter ranges seem to be of near equal importance in determining fertility of yearlings which as a group are sexually and physically immature. Summer range conditions are of greater importance in determining fertility of older does.