Grassland Bird Effect Analysis and Application to Roadway Projects

Evan Markowitz
Topic Area
Terrestrial Wildlife and Ecosystem Interactions with Transportation

The potential for adverse effects to grassland birds, one of the most imperiled groups of birds, and other passerine birds as a result of construction and operation of roadways is of concern for projects within or adjacent to suitable habitat. An analysis of peer-reviewed literature indicates the complexity of determining the effect of noise on avian species, including that from roadway projects. This is exemplified by several studies that show positive, neutral, and/or negative effects for specific avian species. Based on the available literature, assumptions, and limitations of studies completed, a review of the ecological and biological characteristics of passerine species studied and those known to occur, an impact assessment methodology was identified and applied to a proposed roadway project adjacent to grassland bird habitat. An area of Potential Indirect Noise Impact was identified, and additional analysis was conducted using population capacity, habitat requirement, nest-effect, and masking analysis. To assess the potential for masking, absolute threshold and critical ratio of avian species was compared to approximated noise levels from build and no-build conditions within suitable habitat. This analysis provided a basis for coordination with interested stakeholders and identification of avoidance, minimization, and mitigation options for the proposed roadway.

Abstract Keywords
Grassland Birds