Data from: Meteorological conditions influence short-term survival and dispersal in a reinforced bird population.

A high immediate mortality rate of released animals is an important cause of translocation failure (“release cost”). Post-release dispersal (i.e. the movements from the release site to the first breeding site) has recently been identified as another source of local translocation failure. In spite of their potential effects on conservation program outcomes, little is known about the quantitative effects of these two sources of translocation failure and their interactions with environmental factors and management designs.
Based on long-term monitoring data of captive-bred North African houbara bustards Chlamydotis undulata undulata (hereafter, houbara) over large spatial scales, we investigated the relative effects of release (e.g. release group size, period of release), individual (e.g. sex and body condition) and meteorological (e.g. temperature and rainfall) conditions on post-release survival (N = 957 individuals) and dispersal (N = 436 individuals).
We found that (i) rainfall and ambient air temperature had, respectively, a negative and a positive effect on houbara post-release dispersal distance, (ii) in interaction with the release period, harsh meteorological conditions had negative impact on the survival of houbara, (iii) density-dependent processes influenced the pattern of departure from the release site and (iv) post-release dispersal distance was male-biased, as natal dispersal of wild birds (although the dispersal patterns and movements may be influenced by different processes in captive-bred and in wild birds).
Synthesis and applications. Our results demonstrate that post-release dispersal and mortality costs in translocated species may be mediated by meteorological factors, which in turn can be buffered by the release method. As the consequences of translocation programs on population dynamics depend primarily upon release costs and colonisation process, we suggest that their potential interactions with meteorological conditions must be carefully addressed in future programs (i) through monitoring of short-term post-release mortality to understand its link with environmental conditions; (ii) by carefully choosing the season of release to minimize exposition of inexperienced individuals to harsh conditions and (iii) generalising the use of long-term weather forecast to adapt release effort and staggering releases over several years to buffer meteorological effects.

被放归个体的高即时死亡率，是导致易地放归（translocation）失败的重要诱因之一，此类损失亦被称作“放归成本（release cost）”。近期研究表明，放后扩散（post-release dispersal）——即个体从放归位点抵达首个繁殖位点的移动过程——是另一类引发局部易地放归失败的因素。尽管二者均可能对保护项目的实施成效产生潜在影响，但目前学界对这两类易地放归失败诱因的量化效应，及其与环境因子、管理方案间的交互作用仍知之甚少。
本研究基于大空间尺度下的长期监测数据，以人工繁育的北非波斑鸨指名亚种（Chlamydotis undulata undulata，下文简称波斑鸨）为研究对象，共纳入957只个体的放后存活数据、436只个体的扩散数据，旨在解析放归相关因素（如放归群规模、放归时段）、个体特征因素（如性别与身体状况）以及气象条件（如气温、降雨量）对放后存活与扩散的相对影响。
研究结果显示：（1）降雨量与环境气温分别对波斑鸨的放后扩散距离产生负向与正向调控作用；（2）结合放归时段的交互效应来看，严酷的气象条件会对波斑鸨的存活产生负面影响；（3）密度制约过程会影响个体从放归位点的迁出模式；（4）放后扩散距离存在雄性偏向性，这与野生鸟类的出生扩散模式一致——尽管人工繁育个体与野生个体的扩散模式及移动过程可能受不同机制调控。
综合与应用启示。本研究结果证实，易地放归物种的放后扩散与死亡成本，可受气象因子介导，而放归方式可对此类效应起到缓冲作用。鉴于易地放归项目对种群动态的影响主要取决于放归成本与定殖过程，我们建议未来的放归项目需重点关注其与气象条件的潜在交互作用，具体可通过以下途径实现：（1）开展放后短期死亡率监测，以明确其与环境条件的关联；（2）谨慎选择放归季节，以降低无经验个体暴露于严酷环境的概率；（3）推广使用长期天气预报工具，以优化放归工作安排，并通过多年分期放归来缓冲气象因子的不利影响。