Mitigation of Traffic Mortality of Endangered Brown Pelicans on Coastal Bridges

Details

• Creators:
  Owens, L. Karalee ; James, Ray W. ; Slack, R. Douglas
• Corporate Creators:
  Texas Transportation Institute. Texas A&M University
• Corporate Contributors:
  Texas State Department of Highways and Public Transportation ; United States. Department of Transportation. Federal Highway Administration
• Subject/TRT Terms:
  Aerodynamics Bird Strikes Bridges Endangered Species Field Studies Traffic Control Traffic Mitigation Turbulence Wildlife
• Publication/ Report Number:
  FHWA/TX-91 /1226-1 F
• Resource Type:
  Tech Report
• Geographical Coverage:
  Texas ; United States
• Edition:
  Final Report: 9/1/88 - 8/31/90
• Corporate Publisher:
  Texas Transportation Institute. Texas A&M University
• Abstract:
  A field study of the Texas Brown Pelican population and the behavior of the Brown Pelican population in the vicinity of the P100 Bridge between Port Isabel and South Padre Island, Texas was prompted by increasing traffic mortality of the endangered birds. The findings of the field studies, supplemented with wind tunnel studies of the airflow around models of the bridge, led to the conclusions that the mortalities result from a combination of several factors: the greatly increased numbers of birds in the population, the flight patterns of the birds as they fly to roosting sites in the evenings, the occasional presence of strong northerly winds and inclement weather, and the air flow patterns above the bridge deck. It is concluded that the birds are not intentionally landing on the deck, rather a region of pronounced reverse flow, downwash, and turbulence above the deck, similar to the "wind shear" phenomena which has contributed to airplane crashes, causes the birds to land unintentionally on the deck if they attempt to fly over the bridge without sufficient initial altitude. Because of the uncertain effectiveness and expense of aerodynamic modification, several other strategies are recommended for mitigation of the problem. Traffic control, including reduced speed limits during certain critical times and weather conditions, is recommended. Activation of roadway lighting earlier in the evenings is also recommended. Other recommendations are offered for evaluation should traffic control measures alone not provide acceptable mitigation of traffic mortalities.
• Format:
  PDF
• Funding:
  2-5-88/9-1226
• Collection(s):
  US Transportation Collection
• Main Document Checksum:
  urn:sha-512:9a25b47f4117219c206180aa748732d25bb9d25ce93b8ad071ee40344f2e7caa07755de78487872243aaa7e883ea1db66ce4d510d47c1559c96395cf8ca9437b
• Download URL:
  https://rosap.ntl.bts.gov/view/dot/85188/dot_85188_DS1.pdf
• File Type:
  [PDF - 1.92 MB ]