Birds

This study compared the avian communities of treatment wetlands in South Florida called Stormwater Treatment Wetlands (STAs) to those in natural marshes and crop lands, and examined factors that influenced the size and structure of the avian communities within the STAs. The STAs contained a more abundant, rich and distinct avian community compared to reference land types. The STAs were dominated by wintering waterfowl, and therefore community patterns fluctuated more seasonally other land types. Within the STAs, density and richness in the fall and winter were much greater in the submerged aquatic vegetation than in the mixed emergent vegetation when waterfowl were present. The STAs maintain two vegetation treatments which enhanced their biodiversity value by supporting distinct avian communities with different migratory strategies This suggests the increase in treatment wetlands could partially offset the loss of natural wetlands, but avian communities in treatment wetlands are not surrogates for natural wetlands.

The bald eagle, Haliaeetus leucocephalus, population declined dramatically in the early 20th century reducing the population from tens of thousands of birds within the lower 48 states, to <450 pairs of birds, effectively inducing a population bottleneck. The overall population has recovered and was removed from the endangered species list in 2007. This study investigates whether such overall population statistics are appropriate descriptors for this widespread species. I investigated the genetic differentiation between three populations of bald eagles from Alaska, North Florida and Florida Bay using both mitochondrial and nuclear DNA loci to determine whether discrete subpopulations comprise the broad range. Significant FST values, for both mtDNA and microsatellites, were found between both Florida populations and Alaska, but not within Florida populations. Results indicate that there is strong population structure, rejecting the null hypothesis of a panmictic population. Future conservation efforts should focus on subpopulations rather than the overall population.

Wading bird foraging success is influenced by many different factors. From January to March 2008, I conducted a small-scale experiment with three captive Scarlet Ibis (Eudocimus ruber) at the Palm Beach Zoo, in West Palm Beach, Florida. Prey density and the presence of conspecifics were manipulated to test for a response by ibis in terms of prey capture rate. Mixed model analysis, when one prey type was available, showed that capture rate increased significantly with prey density and decreased with the presence of conspecifics. When two prey types were available, prey density and the presence of conspecifics had no effect on the capture rates of either prey type. Selectivity analysis revealed that ibis always selected for crayfish in mixed treatments. I hypothesize that the number of prey types available in a treatment played an important role in determining how fish density and the presence of conspecifics affected ibis foraging success.

The Gull-billed Tern is a globally distributed species. Distribution in the United States is limited, however, with the majority of breeding birds being found in Texas. The remainder can be found scattered throughout the southeastern states. Florida has a mere 1.6% of the breeding birds in the U.S. This study has accumulated all breeding records of the Gull-billed Tern in Florida since 1973, and distribution trends were analyzed. Since 1973 the population of these birds has fluctuated widely and experienced an alarming decline of about "95% between 1975 and 1999" (Smith, in press.). I determined that the current status of this bird in Florida mandates that further conservation efforts occur rapidly in order to protect its diminishing population. This study examines those conservation measures already in place, and those pending, such as my petition to list this species as "threatened" under the endangered species provisions of the Florida Wildlife Code (Chap. 39 F.A.C.).

Habitat fragmentation causes the isolation of groups of individuals within species by producing a new landscape that is uninhabitable for many species, including birds. I surveyed the John D. MacArthur campus of FAU in the Fall of 2005 and Spring of 2006 to assess the use of the campus by birds. Throughout the campus trees are lined in rows along the sidewalks and around buildings, in contrast to the pine flatwoods environment that existed prior to development. The birds observed were found performing various activities on the campus, including foraging, perching, and building nests. Individuals were concentrated around or near buildings with the most diverse vegetation. Through assessing these campus uses I suggest that there are ways we can help increase bird diversity in promoting their use of urban environments. Such solutions can help decrease the number of individuals and species lost to the destructive force of habitat fragmentation.