Beware of hitchhiking ticks? Clarifying the variable roles of bird species in tick movement along migratory routes

Ticks are blood-feeding parasites which act as major vectors for various pathogenic microorganisms affecting both animal and human health. Hard ticks are known to move passively (i.e. ‘hitchhike’) on migratory birds as they transit between breeding and non-breeding grounds. This potentially leads to exchange and establishment of non-endemic tick species in novel environments. However, it is not yet clear if all migratory bird taxa play an equal role in movement of specific tick species, especially outside of medically important tick taxa. To clarify these interactions, we performed a systematic literature review regarding primary data of ticks moving on migratory birds within the African–Western Palearctic flyways. In total, 35 studies were found which showed 123 bird species from 37 families and 12 orders connected to potential movement of 30 tick species representing six genera (Amblyomma, Dermacentor, Haemaphysalis, Hyalomma, Ixodes, Rhipicephalus). Most tick species did not show high abundance for any bird species, or, if they did, only on very few. Only Ixodes ricinus and Hyalomma marginatum were estimated to be carried at above average burdens by multiple bird species. This could indicate an increased likelihood of these species to be moved during migration. Specific tick species or whole genera were only found in certain migratory seasons as expected based on their geographic distributions. Even so, species found in both migratory seasons did not differ in their estimated abundances on birds between seasons. This result could suggest that tick abundance on migrating birds is not always a direct result of geographic distribution and may suggest an understudied importance of stopover sites towards potential tick introduction or turnover. Taken together, the results presented here provide guiding information for future analyses integrating individual level variation into the current understanding of tick movement with migratory birds.

Data included here are the studies and the raw collected data in relation to the above mentioned project.

蜱虫作为一种主要的吸血寄生虫，在动物和人类健康受到多种病原微生物影响的过程中扮演着重要角色。硬蜱虫因其被动迁移方式（即‘搭便车’）而著称，它们随着迁徙鸟类在繁殖地和非繁殖地之间迁移。这种现象可能导致非本土蜱虫物种在新的环境中进行交换和定殖。然而，目前尚不清楚所有迁徙鸟类分类群在特定蜱虫物种的迁移中是否扮演着同等角色，尤其是在对医学具有重要意义的蜱虫分类群之外。为了阐明这些相互作用，我们对非洲-西欧平原迁徙鸟类中蜱虫的原始数据进行了一项系统的文献综述。总计发现了35项研究，这些研究涉及来自37个科和12个目的123种鸟类，以及代表六个属（Amblyomma、Dermacentor、Haemaphysalis、Hyalomma、Ixodes、Rhipicephalus）的30种蜱虫的潜在迁移。大多数蜱虫物种在任何鸟类物种中并未表现出高丰度，或者即使有，也仅限于极少数物种。只有Ixodes ricinus和Hyalomma marginatum被估计为被多种鸟类携带，且携带量超过平均水平。这可能会表明这些物种在迁徙过程中被迁移的可能性增加。正如预期的那样，基于其地理分布，某些特定迁徙季节才能发现特定的蜱虫物种或整个属。尽管如此，在两个迁徙季节中发现的物种在其鸟类中的估计丰度之间并无差异。这一结果可能表明，迁徙鸟类身上的蜱虫丰度并不总是地理分布的直接结果，并且可能暗示了停歇地对于潜在蜱虫引入或转换的重要性尚未得到充分研究。综上所述，此处呈现的结果为未来将个体层面变异整合到当前对蜱虫与迁徙鸟类迁移理解的分析提供了指导信息。