MULTISCALE PATTERNS OF FLOCKING AND ACTIVITIES OF BROWN-HEADED NUTHATCHES

Abstract

Brown-headed Nuthatches (Sitta pusilla) were examined at two sites in Georgia, United States, during winter to assess spatial variation in mixed-species flock participation and in activity patterns (mainly bark traversing, cone foraging, and seed hammering). Spatial variation was examined at four scales: between sites, between habitat-patch types (pine vs. mixed woodland) within a site, between tree species, and among microhabitats within trees. Intersite variation existed for the proportions of nuthatches that were heterospecifically flocked, and that were performing different activities. These variables also varied spatially within the Whitehall site, as evident both from chi-square tests comparing flocking and activity patterns between pine and mixed-habitat patches, and from maps depicting locations of observations. Additionally, nuthatches at Whitehall differed in their choice of pine species when flocked vs. nonflocked. No evidence was found for variation in microhabitat use between sites, or between flocked and nonflocked nuthatches. The potential for processes that determine the distribution of birds at different scales to influence one another, and the role of flocking and activity patterns in these processes, is discussed. [Key words: scale, birds, habitat selection, flocking, animal behavior, nuthatches, Georgia.]