Reproduction in the Female Brown Bear

摘要: Reproduction in the female brown bear (Ursus arctos) was studied by gross examination of 96 reproductive tracts, including 16 from known-age animals, obtained Kodiak Island and Alaska Peninsula during 1959-1965. Additional data were incidental to livetrapping 165 bears aerial surveys made within same period. Gross features tracts indicated females attained sexual maturity when 3 6 years age commonly fourth year life. The breeding season extended May through mid-July as evidenced condition genitals, follicle maturation, observations actual breedings. gestation period estimated be approximately 245 days. Corpora lutea counts disclosed a mean 2.10 ovulations. Placental scar 2.53 conception rate. Litter size averaged 2.23 cubs. Young are weaned prior or second winter denning. Lactation probably inhibited reproduction first summers following parturition. hypothesis is advanced that normally breed at 3-year intervals opposed common belief young produced on alternate years. This paper presents information reobtained cumulative efforts production found authors, who marked censused Peninsula. them with aircraft. We indebted M. Bureau Sport Fisheries Wildlife Talifson, W. Pinnell, other guides cooperated Department supplied many our specimens. also Fish Game combining specimen appreciate R. L. Rausch collections C. Loveless kindly offered suggesThe physiological aspects tions concerning manuscript. photowere based regraphs used this credited productive tracts. Other Zahn. i atio o e forts l ears content downloaded 157.55.39.59 Sat, 15 Oct 2016 04:14:54 UTC All use subject http://about.jstor.org/terms 358 Journal Management, Vol. 33, No. 2, April 1969