Assessing accuracy of a laser rangefinder in estimating grassland bird density

摘要

The use of rangefinders in measuring perpendicular distances for density estimation has potential time-saving advantages in sampling avian populations. However, an important assumption in distance methods is accurate measurement of perpendicular distances. We compared a laser rangefinder to conventional measuring tape in measuring perpendicular distances for the purpose of estimating grassland bird density on Texas rangelands. Distances determined with a measuring tape were highly correlated with distances obtained using a laser rangefinder (r=0.98). The regression of rangefinder distances on tape-measured distances was significant (r(2)=0.963, P<0.001), and the slope of the regression (1.005, SE=0.007) line did not differ from 1 (P=0.226). Examination of standardized residuals indicated that the variance about the regression line was constant at distances less than or equal to100 m.