When you see railway lines, you probably first think of what they do for humans- provide an essential service by transporting people and goods over long distances. However, railway lines not only connect groups of humans, but may also function as habitat corridors for animals across large landscapes.
A new study by Moroń et al. looks at the role of railway lines in connecting pollinator communities in the Kraków region of Poland. To do this, the authors sampled bees, butterflies, and flower-associated flies from both railway embankments and grasslands, and examined differences in the composition of these pollinator communities. Because most of the surrounding land was composed of crop fields, the grassland sites were largely isolated from other natural habitat while the railway lines provided a mostly continuous strip of habitat for pollinators. When the authors compared pollinator communities across the landscape, they found that railway lines positively affected community similarity, such that pollinator communities at railway embankments near to each other were more similar than those far apart. In contrast, the isolated grassland sites showed no overlap in species composition relating to distance from each other or other spatial factors. The authors therefore conclude that railways provide pollinators with a corridor that allows them to disperse more easily than through the surrounding crop fields.
Interestingly, Moroń et al. found that not all pollinator species were affected similarly by railway lines, and that traits such as body size and food preferences determined species’ responses. Only species of butterflies and flies with larger body sizes, which are known to be good long-distance dispersers, responded to railway embankments. Similarly, generalist bee species that visit many different flower species showed a greater response to railways than specialist species.
In sum, this study provides a compelling example of how a landscape feature built for humans can also provide an important function for conserving animals across human-dominated landscapes. Because railways can serve as corridors for pollinators, these and other transport systems should be incorporated into future conservation and connectivity planning. In addition, conservation managers may want to consider ways to improve habitat along railways with pollinator species in mind.
Moroń, D., Skórka, P., Lenda, M., Celary, W., and Tryjanowski, P. 2017. Railway lines affect spatial turnover of pollinator communities in an agricultural landscape. Diversity and Distributions 23(9): 1090–1097.