Avian reproductive success varies depending on environmental conditions, degree of predation, location, and food availability. I examined food availability and nesting habitat of wading birds in South Florida. Evaluating prey availability and prey used by two small heron species demonstrated the ability for small herons to maintain consistent diets through fluctuating environmental conditions, within and across different wetland types. Small herons may be able to cope with environmental changes by altering foraging locations and strategies. Regarding nesting habitat, man-made sites may provide habitat comparable to natural sites, at least in the short-term. The nest’s position can influence its susceptibility to increased temperatures and predators, particularly for. Climatic conditions such as rainfall can also impact nesting success by altering foraging conditions and fish behavior. Understanding the effects of hydrologic regimes on biota can have practical applications since ecosystems around the world share similar problems with competing demands for resources, and there is a concern for how use can affect the quality of the resource. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2018. / FAU Electronic Theses and Dissertations Collection

Thesis--Tekniska högskolan, Stockholm, 1954. / Extra t.p., with thesis statement, inserted. Includes bibliographical references (p. 137-142).

The relationship between water-level fluctuations and wading bird nest numbers and nesting location is well documented, yet species-specific reproductive responses of wading birds to environmental drivers and nesting habitat type is poorly understood. Here, I compared the reproductive responses of two ecologically similar species, Snowy Egret and Tricolored Heron, to foraging conditions influenced by water management and examined the effect of nestling island type on the reproductive success of three wading bird species. Reproductive responses to foraging conditions were broadly similar between Snowy Egrets and Tricolored Herons, however this study revealed specific-specific differences that could lead to different population dynamics in response to management over the long-term. I also found that these two species had lower productivity at spoil islands than marsh colonies, whereas Great Egret productivity did not vary by colony type. This study demonstrates the importance of establishing species-species relationships between productivity and environmental conditions / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2020. / FAU Electronic Theses and Dissertations Collection

Torpedograss (Panicum repens) was first observed in Lake Okeechobee in the 1970s and appears to have displaced an estimated 6,400 ha of native plants, such as spikerush (Eleocharis cellulosa), where inundation depths are often less than 50 cm. Two series of studies evaluated substrate exposure and water depth influences on torpedograss establishment and competitiveness. Results revealed that fragments remain buoyant for extended periods and so facilitate dispersal. Once anchored to exposed substrate fragments can readily root and establish. Subsequently, torpedograss thrives when subjected to inundations to 75 cm and survives prolonged exposure to depths greater than 1 m. These findings suggest that fluctuating water levels contribute to torpedograss dispersal and colonization patterns and that low water levels increase marsh area susceptible to invasion. The competition study found that spikerush grown in monoculture produces significantly more biomass when continually inundated to shallow depths (10 to 20 cm) than when subjected to drier conditions (-25 cm) or greater inundations (80 cm). In contrast, torpedograss establishes more readily on exposed substrate (-25 to 0 cm) compared to inundate substrates. During the first growing season biomass production increases as substrate exposure interval increases. However, during the second year, established torpedograss produces more biomass when grown on intermittently wet (0 cm) compared to permanently dry (-25 cm) or intermittently inundated (10 cm) substrates. No difference in production was observed between substrates permanently inundated (10 cm) and any other regime tested. During the first two years of torpedograss invasion, regardless of treatment, spikerush suppresses invasion and torpedograss had little effect on established spikerush, indicating that spikerush-dominated areas are capable of resisting torpedograss invasion. Even so, disturbances that might cause mortality of long hydroperiod species, such as spikerush, may create open gaps in the native vegetation and thus facilitate torpedograss establishment and expansion.