A Comparison of Fixed-Width Transects and Fixed-Radius Point Counts for Breeding-Bird Surveys in a Mixed Hardwood Forest

The fixed-width strip-transect and fixed-radius point-count survey methods for breeding birds were evaluated side-by-side in 2009, 2010, and 2011 in a 200-ha mixed hardwood forest surrounded by urban development in Parkville, MO. One 2-ha strip transect (80 m × 250 m) and four 0.5-ha fixed-radius plots (40 m radius, 150 m separation) were surveyed in adjacent riparian forest areas during May and June, 2009. In 2010, two additional sets of transects and corresponding circular-plot arrays were installed, bringing the total area surveyed by each method to 6 ha in 2010 and 2011. Abundance of individuals of all species was greater on circular-plot arrays compared with transects in both 2009 and 2010. Modeling the potential intersection of transect and circular-plot arrays on a background simulating a landscape distribution of bird territories at varying densities indicated that a dispersed array of circular survey plots may overlap more bird territories than contiguous strip transects, though both survey plots enclose the same total forest area. The fixed-radius point-count method appears to effectively sample a larger forest patch than the fixed-width transect method, possibly resulting in estimations of bird population parameters that are different between the two methods.