Investigation of breeding peregrine falcons on Virginia bridges.

Details

• Creators:
  Watts, Bryan D ; Watts, Marian U.
• Corporate Creators:
  Virginia Transportation Research Council (VTRC)
• Corporate Contributors:
  Virginia. Dept. of Transportation ; United States. Federal Highway Administration
• Subject/TRT Terms:
  • Birds
  • Inspection
  • Bridges
  • Habitat (Ecology)
  • Endangered species
  • Bridge management systems
  • Peregrine falcons
  • bridge maintenance
  • bird nests
  • nest survey
• Publication/ Report Number:
  FHWA/VTRC 17-R25
• Resource Type:
  Tech Report
• Geographical Coverage:
  Virginia ; United States
• Corporate Publisher:
  Virginia Transportation Research Council (VTRC)
• Abstract:
  Following the extirpation of the peregrine falcon (Falco peregrinus) population in Virginia by the early 1960s and an ; aggressive restoration program during the 1970s and 1980s, the population has undergone a slow but steady recovery to more ; than 30 breeding pairs. Bridges have played a significant role in this recovery, consistently supporting more than 30% of the ; known population. Due to regulatory restrictions, this role has increased operational costs and caused concerns for bridge ; management and maintenance. One of the ongoing challenges faced by the Virginia Department of Transportation (VDOT) is the ; uncertainty and associated financial risk stemming from not knowing the occupancy status of many bridges. The objectives of ; this study were (1) to determine occupancy for bridges in the Coastal Plain, (2) to test a rapid survey protocol for determining ; occupancy, (3) to assess bridge characteristics that attract falcons to bridges, and (4) to conduct a retrospective assessment of ; current peregrine management techniques used on bridges. ; The authors conducted 166 surveys of bridges (n = 83) in coastal Virginia using a call-broadcast protocol. Eleven ; (13.3%) bridges were occupied by falcons, including 10 pairs that produced 11 young. Broadcast calls were extremely effective ; in eliciting a response from falcons with nearly 60% and 100% of falcons responding within five and 30 seconds of call initiation, ; respectively. Occupied bridges were not a random subset of those surveyed but supported more potential nest sites, were longer ; and higher, and were embedded within landscapes with more foraging habitat compared to unoccupied bridges. Lift and draw ; bridges were particularly attractive, with 60% of those available supporting pairs. The current practice of installing nest boxes or ; trays has resulted in higher breeding success and reproductive output. ; Findings from this study have implications for reducing uncertainty in peregrine falcon management on bridges. Callbroadcast ; surveys were effective and should be used to expand the set of bridges monitored annually to improve the planning and ; scheduling of maintenance projects. Current peregrine management techniques improve breeding performance but may also ; reduce maintenance conflicts and should be continued. The bridges identified in this study as occupied by falcons or that have a ; high potential to be occupied in the near future will be communicated to the appropriate VDOT staff.
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• Format:
  PDF
• Funding:
  107899
• Download URL:
  https://rosap.ntl.bts.gov/view/dot/32360/dot_32360_DS1.pdf
• File Type:
  [PDF - 1.05 MB]
• Collection(s):
  US Transportation Collection
• Main Document Checksum:
  urn:sha256:b20edcfe008a0d27624c3bee782a8489c1251f37d27f080632e9cd904f0d65ac