背景:纳塔尔扩散,出生地点和第一次繁殖地点之间的距离,在种群动态和物种对环境变化的反应中起着基本作用。人口密度被认为是出生扩散的关键驱动因素。然而,很少有研究能够检查出生和定居地点的密度,这对于理解密度在扩散中的作用至关重要。此外,在长寿和缓慢繁殖的物种中,密度对出生扩散的作用仍然知之甚少,由于其延长的传播期和通常难以捉摸的性质。我们研究了白尾鹰(Haliaeetusalbicilla)的出生扩散,以响应当地育种者的密度。我们调查了出生部位周围活跃区域数量对(a)出生扩散距离和(b)出生和定居部位饲养者密度之间差异的影响。我们对老鹰是否表现出同种吸引(正密度依赖性)或种内竞争(负密度依赖性)的趋势以及这与定居地点饲养员密度的关系感兴趣。
方法:我们使用了长期视觉和基因型鉴定的组合,以将个体从其繁殖地点匹配到其出生巢。我们确定了1984年至2015年之间在波罗的海沿岸和芬兰北极地区孵化的355名个体的出生扩散事件。其中,251由他们的基因型鉴定。
结果:出生在高密度地区的人比出生在低密度地区的人分散更短的距离,但与出生地点相比,定居在密度较低的繁殖地点。与出生地点相比,在低出生地区密度出生的老鹰分散得更远,但定居在密度更高的繁殖地点。
结论:我们表明,鹰可能会被物种(正密度依赖性)吸引,以识别高质量的栖息地或寻找配偶,但不要在人口最稠密的地区定居。这表明出生扩散受到同种吸引力和种内竞争相互作用的影响,这对白尾鹰的种群动态有影响,还有其他顶级捕食者。此外,我们的研究证明了长期收集雏鸟和(非侵入性)成人DNA样本的价值,然后使用基因型匹配来识别长寿和难以捉摸的物种中的个体。
BACKGROUND: Natal dispersal, the distance between site of birth and site of first breeding, has a fundamental role in population dynamics and species\' responses to environmental changes. Population density is considered a key driver of natal dispersal. However, few studies have been able to examine densities at both the natal and the settlement site, which is critical for understanding the role of density in dispersal. Additionally, the role of density on natal dispersal remains poorly understood in long-lived and slowly reproducing species, due to their prolonged dispersal periods and often elusive nature. We studied the natal dispersal of the white-tailed eagle (Haliaeetus albicilla) in response to local breeder densities. We investigated the effects of the number of active territories around the natal site on (a) natal dispersal distance and (b) the difference between natal and settlement site breeder density. We were interested in whether eagles showed tendencies of conspecific attraction (positive density-dependence) or intraspecific competition (negative density-dependence) and how this related to settlement site breeder density.
METHODS: We used a combination of long-term visual and genotypic identification to match individuals from their breeding site to their natal nest. We identified natal dispersal events for 355 individuals hatched between 1984 and 2015 in the Baltic Sea coast and Arctic areas of Finland. Of those, 251 were identified by their genotype.
RESULTS: Individuals born in high-density areas dispersed shorter distances than those born in low-density areas, but settled at lower density breeding sites in comparison to their natal site. Eagles born in low natal area densities dispersed farther but settled in higher density breeding sites compared to their natal site.
CONCLUSIONS: We show that eagles might be attracted by conspecifics (positive density-dependence) to identify high-quality habitats or find mates, but do not settle in the most densely populated areas. This indicates that natal dispersal is affected by an interplay of conspecific attraction and intraspecific competition, which has implications for population dynamics of white-tailed eagles, but also other top predators. Furthermore, our study demonstrates the value of long-term collection of both nestling and (non-invasive) adult DNA samples, and thereafter using genotype matching to identify individuals in long-lived and elusive species.