Roads and traffic have been implicated in population declines in a number of taxonomic groups. However, there is little research into the potential effects of roads or traffic on spiders. Here, we tested the prediction that there would be fewer aerially-dispersing (i.e., ballooning) spiders at high-traffic than low-traffic roads. We used custom-made sticky traps attached to a vehicle to collect ballooning spiders along 10 high-traffic-low-traffic rural road pairs in southeastern Ontario, Canada. We collected half as many spiders at high-traffic than low-traffic roads. This provides the first published evidence of negative traffic effects on ballooning spiders. Although consistent with our prediction that ballooning spiders are less abundant at high-traffic roads, there are several possible explanations for this finding. Further study is needed to investigate these explanations, including whether the observed traffic effect reflects reduced population sizes near high-traffic roads or reduced ballooning behaviour near high-traffic roads. If the former, then roads may represent a significant conservation concern for ballooning spider species.

Ballooning, road ecology, road kill, traffic intensity, traffic volume
Department of Biology

Martin, A.E. (Amanda E.), Pervin, E. (E.), Graham, S.L. (S. L.), Henry, M. (M.), & Fahrig, L. (2019). Abundance of Aerially-Dispersing Spiders Declines with Increasing Road Traffic. Ecoscience, 26(4), 383–388. doi:10.1080/11956860.2019.1629060