Details:

Creators:
Watts, Bryan D ; Watts, Marian U.
Watts, Bryan D ; Watts, Marian U. Less -
Corporate Creators:
Virginia Transportation Research Council (VTRC)
Corporate Contributors:
Virginia. Dept. of Transportation ; United States. Federal Highway Administration
Virginia. Dept. of Transportation ; United States. Federal Highway Administration Less -
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
Virginia ; United States Less -
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:

Supporting Files

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