The demography of a population is often reduced to the apparent (or local) survival of individuals and their realised fecundity within a study area defined according to logistical constraints rather than landscape features. Such demographics are then used to infer whether a local population contributes positively to population dynamics across a wider landscape context. Such a simplistic approach ignores a fundamental process underpinning population dynamics: dispersal. Indeed, it has long been accepted that immigration contributed by dispersers that emigrated from neighbouring populations may strongly influence the net growth of a local population. To date however, we lack a clear picture of how widely immigration rate varies both among and within populations, in relation to extrinsic and intrinsic ecological conditions, even for the best‐studied avian and mammalian populations. This empirical knowledge gap precludes the emergence of a sound conceptual framework that ought to inform conservation and population ecology. This review, conducted on both birds and mammals, has thus three complementary objectives. First, we describe and evaluate the relative merits of methods used to quantify immigration and how they relate to widely applicable metrics. We identify two simple and unifying metrics to measure immigration: the immigration rate it defined as the ratio of the number of immigrants present in the population at time t + 1 and the total breeding population in year t, and πt, the proportion of immigrants among new recruits (i.e. new breeders). Two recently developed methods are likely to provide the most valuable data on immigration in the near future: individual parentage (rather than population) assignments based on genetic sampling, and spatially explicit integrated population models combining multiple sources of demographic data (survival, fecundity and population counts). Second, we report on a systematic literature review of studies providing a quantitative measure of immigration. Although the diversity of methods employed precludes detailed analyses, it appears that the number of immigrants exceeds locally born individuals in recruitment for most avian populations (median πt = 0.57, N = 45 estimates from 37 studies), a figure twofold higher than estimated for mammalian populations (median πt = 0.26, N = 33 estimates from 11 studies). Third, recent quantitative studies reveal that immigration can be the main driver of temporal variation in population growth rates, across a wide array of demographic and spatial contexts. To what extent immigration acts as a regulatory process has however been considered only rarely to date and deserves more attention. Overall, it is likely that most populations benefit from immigrants without necessarily being sink populations. Furthermore, we suggest that quantitative estimates of immigration should be core to future demographic studies and plead for more empirical evidence about the ways in which immigration interacts with local demographic processes to shape population dynamics. Finally, we discuss how to tackle spatial population dynamics by exploring, beyond the classical source–sink framework, the extent to which populations exchange individuals according to spatial scale and type of population distribution throughout the landscape.

中文翻译：

---

量化移民对人口动态的贡献：对鸟类和哺乳动物的方法、证据和观点的回顾

人口的人口统计学通常被简化为根据后勤限制而不是景观特征定义的研究区域内个体的表观（或局部）存活率及其实现的繁殖力。然后使用这些人口统计数据来推断当地人口是否对更广泛的景观背景下的人口动态做出了积极贡献。这种简单的方法忽略了支撑人口动态的一个基本过程：分散。事实上，人们早就认为，由邻近人口迁出的分散者造成的移民可能会强烈影响当地人口的净增长。然而，迄今为止，我们还没有清楚地了解移民率在人口之间和人口内部的差异有多大，与外在和内在生态条件有关，即使对于研究最深入的鸟类和哺乳动物种群也是如此。这种经验知识差距阻碍了一个健全的概念框架的出现，该框架应该为保护和种群生态学提供信息。因此，对鸟类和哺乳动物进行的审查具有三个互补的目标。首先，我们描述和评估用于量化移民的方法的相对优点以及它们如何与广泛适用的指标相关。我们确定了两个简单而统一的衡量移民的指标：移民率定义为时间 t + 1 时人口中存在的移民人数与 t 年的总繁殖人口之比，以及 πt，移民在人口中的比例。新兵（即新饲养员）。最近开发的两种方法可能会在不久的将来提供最有价值的移民数据：基于遗传抽样的个体血统（而不是人口）分配，以及结合多种人口统计数据来源（存活率、繁殖力和人口计数）的空间明确的综合人口模型。其次，我们报告了对提供移民定量测量的研究的系统文献综述。尽管所采用方法的多样性无法进行详细分析，但对于大多数鸟类种群而言，似乎移民人数超过了当地出生的个体（中位数 πt = 0.57，N = 45 来自 37 项研究的估计值），该数字比哺乳动物估计值高两倍人群（中位数 πt = 0.26，N = 33 来自 11 项研究的估计值）。第三，最近的定量研究表明，移民可能是人口增长率随时间变化的主要驱动因素，跨越广泛的人口统计和空间背景。然而，迄今为止，移民在多大程度上作为监管程序被认为很少，值得更多关注。总体而言，大多数人口可能从移民中受益，但不一定是汇人口。此外，我们建议移民的定量估计应该是未来人口研究的核心，并呼吁提供更多关于移民与当地人口过程相互作用以塑造人口动态的方式的经验证据。最后，我们讨论了如何通过超越经典的源汇框架探索种群根据空间尺度和整个景观中的种群分布类型交换个体的程度，来讨论如何解决空间种群动态问题。然而，移民在多大程度上充当监管程序，迄今为止很少被考虑，值得更多关注。总体而言，大多数人口可能从移民中受益，但不一定是汇人口。此外，我们建议移民的定量估计应该是未来人口研究的核心，并呼吁提供更多关于移民与当地人口过程相互作用以塑造人口动态的方式的经验证据。最后，我们讨论了如何通过超越经典的源汇框架探索种群根据空间尺度和整个景观中的种群分布类型交换个体的程度，来讨论如何解决空间种群动态问题。然而，移民在多大程度上充当监管程序，迄今为止很少被考虑，值得更多关注。总体而言，大多数人口可能从移民中受益，但不一定是汇人口。此外，我们建议移民的定量估计应该是未来人口研究的核心，并呼吁提供更多关于移民与当地人口过程相互作用以塑造人口动态的方式的经验证据。最后，我们讨论了如何通过超越经典的源汇框架探索种群根据空间尺度和整个景观中的种群分布类型交换个体的程度，来讨论如何解决空间种群动态问题。