Age at sexual maturity of males and timing of the mating season of polar bears (<i>Ursus maritimus</i>) in Greenland

作     者：Rosing-Asvid, A Born, EW Kingsley, MCS 

作者机构：Greenland Inst Nat Resources Nuuk 3900 Greenland Univ Copenhagen Dept Populat Ecol DK-2100 Copenhagen Denmark 

出 版 物：《POLAR BIOLOGY》 (极地生物学)

年 卷 期：2002年第25卷第12期

页      面：878-883页

核心收录：

学科分类：0710[理学-生物学] 07[理学] 09[农学] 0713[理学-生态学] 

基　　金：Pinngortitaleriffik  GINR 

摘      要：Age at sexual maturity among male polar bears (Ursus maritimus) and timing of the mating season were studied by microscopic and macroscopic analysis of the reproductive organs from 165 male and 92 female Greenland polar bears. Males became sexually mature in the spring following their fifth birthday. Testes sampled during the spring reached 95% of their asymptotic length at 5.8 years. Some spermatozoa were found in 2- to 4-year-old bears during the spring, but only in low concentrations in a mixture of other cell types. The first corpus luteum was found on 1 April and most ovulations were estimated to occur before mid-May which indicate that the peak of the mating season begins in late March and ends in May. These findings are somewhat different from a similar study from Svalbard, where the mating season is estimated to peak later and male polar bears are found to become mature earlier. We hypothesize that these differences occur because adolescent males have their peak testicular activity after the main breeding period and therefore appear to be fully sexually mature during summer and not during spring.