Program in Ecology, Evolution, and Conservation Biology, University of Illinois, Shelford Vivarium, 606 East Healey Street, Champaign, Illinois 61820, USA.
Ecology. 2011 Jun;92(6):1271-81. doi: 10.1890/10-1386.1.
The factors that affect survival until reproduction are essential to understanding the organization of life histories within and among species. Theory predicts, for example, that survival until reproduction influences the optimum level of reproductive investment by parents, which might partly explain prolonged parental care in species with high first-year survival. Tests and refinements of life-history theory have been hampered, however, by a lack of field-based estimates of pre-reproductive survival, especially for tropical species, which have been the subject of many comparative analyses. Tropical species are predicted to have higher first-year survival and delayed reproduction compared to Northern Hemisphere species. We estimated survival until reproduction, age at first reproduction, and sources of variation in juvenile survival in a Neotropical passerine, the Western Slaty-Antshrike (Thamnophilus atrinucha), in central Panama. We observed that fledged antshrikes had 76% survival through the dependent period and 48% survival to the age of 1 year; survival rate was lowest during the first week after leaving the nest. Timing of fledging within the breeding season, fledgling mass, and age at dispersal influenced survival, while sex of offspring and year did not. Individuals did not breed until two years of age, and post-fledging pre-reproductive survival was 41% of annual adult survival. High survival until reproduction in antshrikes balanced their low annual productivity, resulting in a stable population. Survival during the post-fledging period of dependence and the first year of independence in the Western Slaty-Antshrike exceeded estimates for Northern Hemisphere species. This difference appears to be associated with the extended post-fledging parental care, delayed dispersal, low costs of dispersal, and the less seasonal environment of antshrikes.
影响繁殖前生存的因素对于理解物种内和物种间的生命史组织至关重要。例如，理论预测，繁殖前的生存会影响父母的最佳生殖投资水平，这在第一年生存率较高的物种中，可能部分解释了延长的亲代抚育。然而，由于缺乏基于野外的繁殖前生存估计，特别是对于许多比较分析的热带物种，生命史理论的测试和改进受到了阻碍。与北半球物种相比，热带物种预计会有更高的第一年生存率和延迟的繁殖。我们在巴拿马中部的一个新热带雀形目鸟类——西部石板蚁鸟（Thamnophilus atrinucha）中估计了繁殖前的生存、首次繁殖的年龄以及幼鸟生存的变异来源。我们观察到，羽翼丰满的蚁鸟在依赖期的存活率为 76%，1 岁时的存活率为 48%；离开巢穴后的第一周，存活率最低。繁殖季节内的出雏时间、雏鸟体重和扩散年龄影响了存活率，而后代的性别和年份没有影响。个体直到两岁才开始繁殖，出雏后繁殖前的存活率为成年个体年存活率的 41%。蚁鸟繁殖前的高存活率平衡了它们低的年度生产力，导致了一个稳定的种群。在依赖期的出雏后阶段和在西部石板蚁鸟的独立的第一年的生存，超过了对北半球物种的估计。这种差异似乎与延长的出雏后亲代抚育、延迟的扩散、低扩散成本以及蚁鸟较少的季节性环境有关。
