Research Projects

Best Management Practices for worm control at airports

Provide airports with best management practices/strategies for worm control that focuses on effectiveness, cost and environmental stewardship with special attention to avoid adverse impacts on Federally listed species under the Endangered Species Act as well as other non-target species. The identification of these practices/strategies would reduce the risk to safe airport operations and the costs resulting from bird/aircraft collisions (bird strikes).

Background (Describe the current situation or problem in the industry, and how your idea would address it.)

During and following rain events, earthworms are often forced to impervious surfaces such as runways, taxiways, ramps and aprons due to a lack of oxygen in saturated soils. Worms on the aircraft movement areas are known to be a food source and attract species of birds that are a high risk to safe airport operations, such as raptors and gulls. Proactive aviation wildlife hazard management is required to reduce the risk of bird strikes. Human life safety is paramount at airports but the costs to aircraft operations resulting from damaging bird strike events must also be managed.

Airports have implemented many strategies to keep earthworms off aircraft movement areas with the intent of reducing the risk to human life safety and aircraft operations. Airports with robust financial resources have installed extensive infrastructure such as French drains as a way of excluding earthworms from specific surfaces. At other airports, chemical applications have been utilized with some efficacy; however, there are currently no registered toxicants or repellants specifically for earthworms in the United States (Seamans et al. 2015). Other options such as abrasive aggregate and soil pH reduction have been less successful (Potter et al. 2013; Williamson & Hong, 2004). Many effective management strategies are often too costly for most airports or have adverse effects on the environment and non-target species.

Research on this subject would increase safety, reduce costs associated with bird strikes and would greatly benefit the aviation community across the nation. In the United States, human fatalities and injuries due to bird strikes include many species that are known to forage for earthworms on aircraft movement area surfaces. Raptors and gulls alone account for over 17% of identified bird strikes in the United States. Strike damage from these species has amounted to 233,359 hours of down time and $202,576,519 in reported costs (Dolbeer et al. 2019). These numbers underscore the need to provide airports with best management practices/strategies for worm control that focuses on effectiveness, cost and environmental stewardship.

Submitted by the PDX Wildlife Department at the Port of Portland (PDX)


Casey Kaffka
Aviation Wildlife Supervisor
Port of Portland

Nick Atwell
Sr. Natural Resources & Wildlife Manager
Port of Portland


Literature Cited

Dolbeer, R.A., Begier, M.J., Miller, P.R., Weller, J.R., and Anderson, A.L. (2019). Wildlife strikes to civil aircraft in the United States, 1990–2018. Serial Report Number 25. Federal Aviation Administration, Office of Airport Safety and Standards, Washington, D.C. 104pp.

Potter, D. A., C. T. Redmond, and D. W. Williams. 2013. Managing excessive earthworm casting on golf courses and sport fields. International Turfgrass Society Research Journal 12:347–356.

Seamans, T. W., Blackwell, B. F., Bernhardt, G. E., & Potter, D. A. (2015). Wildlife Society Bulletin: Volume 39, Number 2. Wildlife Society Bulletin, 39(2), 434–442. doi: 10.1002/wsb.545

Williamson, R. C., and S. Hong. 2004. Managing earthworm casting in golf course turf. USGA Turfgrass and Environmental Research Online 3:1–6.



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Idea No. 398