Influence of Sample Size and Sampling Design on Analysis of Avian Foraging Behavior

Abstract

The influence of sampling scheme and sample size on results of foraging behavior of the hermit (Dendroica occidentalis) and black-throated gray (D. nigrescens) warblers using both single point and sequential observational methods was analyzed. Single point observations gave results similar to those of sequential observations except for the use of foraging heights and species of tree; infrequently used heights and tree species were not detected by the single point method. Making sequential observations apparently allows an observer to follow an individual bird through a wider range of activities (e.g., use of low heights) as compared to single point observations. At least 30 individuals constitute the minimum sample necessary to analyze foraging behavior. Statistical problems associated with the sequential observation method and suggestions for alternative methods of sampling foraging behavior are discussed.