Conservation Biology Graduate Program, University of Minnesota, 2003 Upper Buford Circle, Suite 135, St. Paul, MN 55108, USA.
Minnesota Zoo, Conservation Department, 12101 Johnny Cake Ridge Road, Apple Valley, MN 55124, USA.
Anim Reprod Sci. 2014 Jan 10;144(1-2):38-47. doi: 10.1016/j.anireprosci.2013.11.006. Epub 2013 Nov 28.
Understanding factors that influence reproduction and offspring survival in zoo populations is critical for management of threatened and endangered species. Examination of long-term data (1989-2011) compiled from the Association of Zoos and Aquarium's zoo-managed tiger breeding program provides the basis for a more thorough understanding of reproduction and scientifically based decisions for effective population management in this endangered felid. Biological and management-related factors that could influence tiger breeding success and cub survival were evaluated using logistic mixed models. Breeding success improved with female age until approximately age five, then declined thereafter. Experienced female breeders had greater breeding success than inexperienced females. Litter size was most predictive of cub survival, with average-sized litters (3-4 cubs) experiencing the highest proportional survival. Management-related factors, such as whether the breeding institution had a recent tiger litter and whether both animals were already located at the same institution, also influenced breeding success and cub survival. These results highlight the importance of institutional husbandry experience and the need to retain knowledge through staff turnovers to achieve optimal reproductive success. Using fecal estrogen data, frequency of ovarian cyclicity and mean cycle length did not differ by female age or parity; thus, lack of cyclicity and/or increased cycle duration are not likely explanations for declining breeding success with age. These results provide valuable reproductive information that should improve scientific management of zoo-based tiger populations.
了解影响动物园种群繁殖和后代生存的因素对于濒危和受威胁物种的管理至关重要。对动物园管理的老虎繁殖计划的长期数据（1989-2011 年）的检查为更深入地了解繁殖提供了基础，并为这种濒危猫科动物的有效种群管理做出了基于科学的决策。使用逻辑混合模型评估了可能影响老虎繁殖成功率和幼崽存活率的生物学和管理相关因素。繁殖成功率随着母虎年龄的增长而提高，直到大约五岁左右，然后下降。有经验的雌虎繁殖者比没有经验的雌虎繁殖成功率更高。幼崽数量是幼崽存活率的最主要预测因素，中等大小的幼崽（3-4 只幼崽）的存活率最高。管理相关因素，如繁殖机构是否有最近的老虎幼崽，以及两只动物是否已经在同一机构，也会影响繁殖成功率和幼崽存活率。这些结果强调了机构饲养经验的重要性，并且需要通过员工流动来保留知识，以实现最佳的繁殖成功率。使用粪便雌激素数据，卵巢周期性和平均周期长度的频率不因母虎年龄或胎次而异；因此，缺乏周期性和/或周期持续时间延长不太可能是随着年龄增长繁殖成功率下降的原因。这些结果提供了有价值的繁殖信息，应该会改善基于动物园的老虎种群的科学管理。
