Relative Distribution and Abundance of Wintering Raptors in Agricultural and Wetland Landscapes of South Florida

South Florida provides important winter habitat for a variety of migratory and resident raptor species (Bohall and Collopy 1984). In this area, habitat loss has occurred as natural habitat has been modified for either agriculture or urban use. Two predominant features of the current vegetated landscape are Everglades wetland communities and agricultural areas (Pearlstine et al. 2001), including sugarcane-dominated (Saccharum sp.) fields south and east of Lake Okeechobee in the Everglades Agricultural Area (EAA). Although the two habitats are open and contain superficially similar components such as upland, wetland, temporary and permanent water, and sparsely-distributed trees, structure and composition varies greatly between natural and agricultural habitat. Roadside surveys are convenient for obtaining information on distribution, population trends, and abundance of raptors (Fuller and Mosher 1981). Such surveys have been used extensively to determine relative abundance (e.g., Woffinden and Murphy 1977, Leptich 1994, Eakle et al. 1996, Meunier et al. 2000), population trends (e.g., Layne 1980), habitat associations (e.g., Preston 1990, Sorley and Anderson 1994, Garner and Bednarz 2000, Thiollay and Rahman 2002), perch use (e.g., Bohall and Collopy 1984, Smallwood et al. 1996, Meunier et al. 2000, Leyhe and Ritchison 2004), activity patterns (e.g., Meunier et al. 2000), and species richness and diversity (e.g., Leptich 1994, Sorley and Anderson 1994). However, a number of factors may cause variation in raptor counts including differences in detectability across cover types, distance of observation (Millsap and LeFranc 1988) and time of day (Bunn et al. 1995). Migratory and wintering hawks begin arriving in south Florida in October and are present throughout the winter. They can be easily observed along roadsides and flying over the landscape. The purpose of our study was to compare relative distribution and abundance of common wintering raptors in agricultural and wetland landscapes. Our null hypotheses were that there was no difference in raptor abundance and diversity between the two habitats and that perch types were chosen randomly.