A Comparison of Avian Abundance and Species Richness in Palustrine Emergent Wetlands in Southwest Florida

Matthew P. Miller

A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science Department of Environmental Science and Policy College of Arts and Sciences University of South Florida Saint Petersburg.

Abstract

Wetlands are commonly thought of as transition areas between dry, upland habitats and deepwater habitats and can be the hydrologic gradient between a dry landscape and a lake or river, or they be can isolated from a flowing or deepwater system and completely surrounded by a dry landscape (Tiner 2001). Wetlands provide a valuable suite of services including providing foraging, nesting and denning habitat for birds, amphibians and other wildlife (Environmental Law Institute 2008; Stolt, et al. 2001). In southwest Florida, population growth has put enormous pressure on wetland landscapes. Wetland regulations in the state of Florida make clear that a wetland shall not be considered impacted by development if an undisturbed buffer averaging 25 feet is designed around a wetland (and minimum of 15 feet) remains (Southwest Florida Water Management District, Basis of Review, 2011). Four small (2-4 acre) palustrine emergent wetlands in Sarasota County, Florida were selected for analysis of their function as bird habitat by conducting avian surveys. Two of these wetlands are control wetlands (no development within one half mile) and the other two are urban (nearby residential development, with a 25 foot average buffer). There was no statistically significant difference between the median abundance and species richness of total birds found within, flying over or adjacent to the control and urban wetlands during the marsh bird breeding (dry) season (Mann-Whitney U: χ2 = 0.1656; p = 0.6841 and χ2 = 0.8614; p = 0.3533respectively). This study also found no statistically significant evidence that small palustrine emergent wetlands in southwest Florida surrounded by a natural landscape v support a greater abundance or species richness of marsh birds than similar wetlands surrounded by a small upland buffer and urban development. Factors such as the absence of water and the presence of a predator (coyote) likely contributed to this result, but these factors require further investigation before one can conclude that small upland buffers surrounding urban wetlands are sufficient for maintaining marsh bird populations.