Land Cover Sampling Biases Associated with Roadside Bird Surveys

Roadside surveys such as the Breeding Bird Survey (BBS) are widely used to assess the relative abundance of bird populations. The accuracy of roadside surveys depends on the extent to which surveys from roads represent the entire region under study. We quantified roadside land cover sampling bias in Tennessee, USA, by comparing land cover proportions near roads to proportions of the surrounding region. Roadside surveys gave a biased estimate of patterns across the region because some land cover types were over- or underrepresented near roads. These biases changed over time, introducing varying levels of distortion into the data. We constructed simulated population trends for five bird species of management interest based on these measured roadside sampling biases and on field data on bird abundance. These simulations indicated that roadside surveys may give overly negative assessments of the population trends of early successional birds and of synanthropic birds, but not of late-successional birds. Because roadside surveys are the primary source of avian population trend information in North America, we conclude that these surveys should be corrected for roadside land cover sampling bias. In addition, current recommendations about the need to create more early successional habitat for birds may need reassessment in the light of the undersampling of this habitat by roads.

Comparison of Two Roadside Survey Procedures for Dwarf Mistletoes on the Sawtooth National Forest, Idaho

Two roadside surveys were conducted for dwarf mistletoes parasitizing lodgepole pine and Douglas-fir on the Sawtooth National Forest, Idaho. One survey used variable-radius plots located less than 150 m from roads. The 2nd survey used variable-radius plots established at 200-m intervals along 1600-m transects run perpendicular to the same roads. Estimates of the incidence (percentage of trees infected and percentage of plots infested) and severity (average dwarf mistletoe rating) for both lodgepole pine and Douglas-fir dwarf mistletoes were not significantly different for the 2 survey methods. These findings are further evidence that roadside-plot surveys and transect-plot surveys conducted away from roads provide similar estimates of the incidence of dwarf mistletoes for large forested areas.

Roadside interview survey. 1971. Report.

Mode of access: Internet.

County of Los Angeles Alcohol Safety Action Project roadside survey - 1975. Final report.

National Highway Traffic Safety Administration, Washington, D.C.

Lincoln Alcohol Safety Action Project. Roadside survey report. 1971-1972.

National Highway Traffic Safety Administration, Washington, D.C.

Roadside survey - Utah ASAP. Final report.

Utah Department of Public Safety, Salt Lake City

Analysis of 1976 roadside survey of Hennepin County driver population.

National Highway Traffic Safety Administration, Office of Driver and Pedestrian Programs, Washington, D.C.

Roadside survey, Utah ASAP. Evaluation extention final report.

National Highway Traffic Safety Administration, Washington, D.C.

Daytime roadside survey: a description of daytime driving and drinking patterns. Final report.

National Highway Traffic Safety Administration, Washington, D.C.

Public acceptability of highway safety countermeasures. Volume III: alcohol and drug research. Final report.

National Highway Traffic Safety Administration, Washington, D.C.

Public acceptability of highway safety countermeasures. Volume V: summary report. Final report.

National Highway Traffic Safety Administration, Washington, D.C.

Restraint usage and effectiveness on the National Crash Severity Study.

Mode of access: Internet.

A survey of public attitudes toward the S.D. ASAP: baseline period (1971).

Alcohol Safety Action Project--South Dakota, Pierre

Baseline data for public education about alcohol and highway safety in Vermont.

National Highway Traffic Safety Administration, Washington, D.C.