Natal dispersal of whooping cranes in the reintroduced eastern migratory population

Natal dispersal is a key demographic process for evaluating population rate of change, especially for long-lived, highly mobile species. This process is largely unknown for reintroduced populations of endangered avian species. We evaluated natal dispersal distances (NDD) for male and female Whooping Cranes (Grus americana) introduced into two locations in central Wisconsin (Necedah National Wildlife Refuge, or NNWR, and the Eastern Rectangle, or ER) using a series of demographic, spatial, and life history related covariates. Data were analyzed using Gamma Regression models with a log-link function and compared using Akaike Information Criterion corrected for small sample sizes (AICc). Whooping Cranes released in the ER dispersed 261% further than those released into NNWR, dispersal distance increased 4% for each additional nesting pair, decreased about 24% for males as compared to females, increased for 21% for inexperienced pairs, and decreased 3% for each additional year of age. Natal...出生扩散（natal dispersal）是评估种群变化率的关键人口统计过程，尤其适用于长寿且高移动性的物种。针对濒危鸟类的再引入种群，这一过程的相关信息仍较为匮乏。本研究针对引入至威斯康星州中部两处区域——内塞达国家野生动物保护区（Necedah National Wildlife Refuge, 简称NNWR）与东部矩形区域（Eastern Rectangle, 简称ER）的雌雄美洲鹤（Whooping Crane，学名*Grus americana*）的出生扩散距离（natal dispersal distances, NDD）展开评估，所用协变量（covariates）涵盖人口统计、空间特征及生活史相关因素。研究采用带有对数连接函数（log-link function）的伽马回归（Gamma Regression）模型对数据进行分析，并利用针对小样本量校正的赤池信息准则（Akaike Information Criterion corrected for small sample sizes, AICc）开展模型比较。结果显示，相较于被释放至NNWR的个体，ER区域释放的美洲鹤扩散距离远出261%；每新增一对筑巢个体，扩散距离增加4%；雄性个体的扩散距离较雌性降低约24%；无繁殖经验的配对个体的扩散距离提升21%；而每增加1岁，扩散距离降低3%。出生扩散……