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:
  Bird Nests Birds Bridge Maintenance Bridge Management Systems Bridges Endangered Species Habitat (Ecology) Inspection Nest Survey Peregrine Falcons
• 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.
  
  
• Format:
  PDF
• Funding:
  107899
• Collection(s):
  US Transportation Collection
• Main Document Checksum:
  urn:sha256:b20edcfe008a0d27624c3bee782a8489c1251f37d27f080632e9cd904f0d65ac
• Download URL:
  https://rosap.ntl.bts.gov/view/dot/32360/dot_32360_DS1.pdf
• File Type:
  [PDF - 1.05 MB ]