Evaluation of Controls to Prevent Nesting Swallows on Highway Structures and Possible Impacts on Nesting and Breeding

Focus Area

Construction and Maintenance Practices


Environmental Process, Natural Resources




Under $99k


1-2 years

Research Idea Scope

The Migratory Bird Treaty Act prohibits work on bridges and CBCs when active swallow nests are present. Controls to prevent nesting swallows on bridges and concrete box culverts not only affect the ability of highway workers to build and repair structures, but may also affect the nesting habits and breeding success of the swallow species. DOTs face a challenging task at balancing construction needs with wildlife concerns governed by the federal Migratory Bird Treaty Act and state law.
The first part of this research would include: a comprehensive literature survey of all known methods currently employed for preventing or discouraging bird nesting; development of a table or matrix of all these methods for ranking based on effectiveness, relative ease of providing access to bridge and maintenance personnel, negative impacts or risks to people, wildlife, environment, and infrastructures, cost effectiveness and life-cycle cost analysis, ease of construction, operation, and maintenance, and compliance with regulatory standards and environmental requirements; and actual testing of some of the promising bird deterrents available in the market.
The second part of the research would focus on the effects of controls on swallows nesting habitats, as protected under the Migratory Bird Treaty Act and Executive Order 13186 (1/11/01) which requires federal agencies to evaluate the effects of proposed projects on migratory birds and to identify and mitigate take which is likely to have a measurable negative effect on migratory bird populations. The second part of the research could include:
  1. Assess the fate of swallows excluded from nesting colonies including impacts on current-year and subsequent-year nest success and productivity.
  2. Assess the impact of various types and increasing levels of disturbance on swallow nest success and productivity. When combined with the results from #1 above, biologists should be better able to recommend management strategies that balance the potential impacts of exclusion against the impacts of disturbance (i.e, exclusion may not always be the least damaging alternative).

TERI Administrator Note (June 2007): Related Research
Arkansas DOT: Evaluation of Passive Bird Deterrent Devices to Minimize Nesting on Bridges and Culverts (Underway)

Abstract: The Arkansas State Highway and Transportation Department (AHTD) only has one approved method, Special Provision, "CONDITIONS FOR REMOVAL OR CONSTRUCTION ON EXISTING BRIDGE AND CULVERT STRUCTURES", for preventing migrating birds, primarily swallows, from nesting on bridges and culverts that need to be removed. This method allows the contractor to install netting before the nesting season and details the appropriate size of netting and installation procedure. The Environmental Division is proposing an alternative method, an ultrasonic bird deterrent, be installed at various test sites to prevent the birds from nesting as an option to netting. The Department’s current Special Provision requires netting to be installed with no more spacing than 1/2 inch. Frequently this installation requires lane closures during installation and maintenance. When installed and maintained correctly, the netting has proven to be very successful in deterring nesting birds. However, due to it’s size and required maintenance it is a labor-intensive installation that requires close monitoring.

Urgency and Payoff

The transportation agency will have various options for handling the nesting problems in different environments, as well as understanding the biological and legal impacts of these decisions for swallow specifies.  Costs associated with each option will be determined.  Examples of specifications that can be inserted in the plans will be developed. Monetary and time savings will be generated for the transportation agency.  Increased safety to transportation employees will be provided.

Suggested By

Debra Angulski; Colorado Department of Transportation, Region 1 Environmental Jack W. Miller California Department of Fish and Game 2002 Research Needs Conference Idea

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