I studied flock composition, distribution and foraging ecology of wintering wading birds along the Gulf of Mexico coast. I focused on geographic variability in wintering wading bird assemblages, the processes that structured these assemblages and habitat use by wading birds. I found considerable variation among three sites, Aransas National Wildlife Refuge (ANWR), Texas; Marsh Island Wildlife Refuge (MIWR), Louisiana; and Chassahowitzka National Wildlife Refuge (CNWR), Florida. Species comprising wintering wading bird assemblages varied regionally. ANWR had the most species-rich assemblage, with eight species. MIWR had only six wading bird species. And CNWR had only three different species. Processes that structured wintering wading bird assemblages also varied regionally. In ANWR, Texas, the Random Fraction niche apportionment model (RF model) best explained the empirical abundance data for ANWR. For abundance data from MIWR a good fit was obtained with the MacArthur Fraction (MF) model and the Power Fraction (PF) models. None of the models fully explained the CNWR abundance data. I also examined patterns of habitat partitioning among wintering wading birds at three different scales at two sites, Matagorda Island National Wildlife Refuge (MINWR) and Laguna Atascosa National Wildlife Refuge (LANWR). At the macrohabitat level, wintering wading birds showed interspecific differences in macrohabitat use of both open water habitats and vegetated flats. At the mesohabitat level all species at MINWR used the category nearest the edge most often, alternatively, at LANWR wading birds were most often in the mesohabitat category of 8.1- 12 m. from the edge. In both locations wading birds partitioned habitat based on water depth. Finally, I found that Great Egrets and Snowy Egrets participated more often in flock foraging and derived more benefits from feeding in flocks than other species. Great Egrets feeding in flocks had a higher mean strike rate than those foraging alone, whereas Snowy Egrets had a higher success rate foraging in flocks than those foraging alone. In the case of the darkercolored species (e.g., Great Blue Herons, etc.) they either showed no difference in behaviors between birds foraging in flocks versus those foraging alone or they actually did worse when they foraged in flocks.

Geographically isolated wetlands (GIWs) within the southeastern U.S. Coastal Plain have been increasingly recognized for their importance in providing ecosystem services. These wetlands serve as valuable foraging and breeding habitat for wetland-dependent species, including wading birds. I quantified wading bird presence in GIWs in southwestern Georgia and determined the relative importance of factors influencing their use of these wetlands. I also examined the diet of a nesting colony of Little Blue Herons; a species experiencing population declines throughout most of the Southeast. I found that wetland-specific parameters were important factors in predicting wading bird use of GIWs, and wading birds utilized agricultural and natural wetlands differently depending on hydrological seasonality. Little Blue Herons were primarily consuming large anurans and anuran larvae, which are characteristic of agriculturally modified wetlands. The seasonal process of receding water levels in GIWs and subsequent concentration of / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2018. / FAU Electronic Theses and Dissertations Collection

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

In tropical wetlands, breeding wading birds rely on concentrations of aquatic fauna during the dry season to meet increased energetic demands. Wetland microtopography increases aquatic fauna concentration levels. Crocodilians modify the landscape creating deep-water refugia but their role as a mechanism for aquatic fauna concentration is unknown. I sampled alligator (Alligator mississippiensis) abundance and slough microtopography to examine correlation between the two measures. Despite increased microtopography in high alligator use sloughs, the differences were not significant. Using an in situ experimental approach, I quantified the magnitude, timing, and spatial extent of aquatic fauna concentrations within simulated alligator depressions and the surrounding marsh. Aquatic fauna density and biomass were greater within simulated depressions, thus enhancing wading bird foraging habitat. Further understanding the mechanisms creating microtopography, thus enhancing wading bird habitat, is critical to facilitate restoration and prevent declines of wading bird populations in seasonally pulsed wetlands worldwide. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2018. / FAU Electronic Theses and Dissertations Collection

Wetland loss and degradation have led to the development of restoration programs worldwide, many of which monitor wading bird populations as indicators of wetland quality. Therefore, efficient, standardized monitoring is integral to restoration progress. I tested the use of passive acoustic monitoring to estimate nest abundances and provisioning rates in wading bird colonies and examined regional nesting dynamics in the Florida Everglades, where a long monitoring record enables analysis of nesting patterns relative to hydrologic changes. I found that call rates can serve as indices of colony nest abundances and begging call rate and timing are indicative of provisioning events. Nesting dynamics suggested that resource availability is asynchronous between regions of the Everglades, but the degree of asynchrony varies with species. The conclusions of this study will facilitate the long-term monitoring of wading bird nesting trends, which are important measures of wetland restoration in Florida and worldwide. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2021. / FAU Electronic Theses and Dissertations Collection

The hydrological and topographical variation of wetlands can affect the behavior, population growth, and local densities of aquatic species, which in turn can drive the behavior and density dynamics of gleaning predators. Prey availability, primarily determined by prey density and water depth in wetlands, is an important limiting factor for nesting wading bird populations, top predators in the south Florida Everglades. The Everglades is able to support large colonies of nesting wading birds because of the microtopographic variation in the landscape. Some types of prey concentrate in flat, shallow sloughs or become trapped in isolated pools as they move down from higher elevation ridges with receding water levels. Manipulations to the hydrology and landscape of the Everglades has negatively impacted nesting wading bird populations in the past, and may continue to be detrimental by allowing flat, shallow sloughs to be intersected by deep canals, a potential refuge for wading bird prey. In addition, the subtle elevation differences between the ridge and slough landscape may be an important mechanism for increasing slough crayfish (Procambarus fallax) prey availability for the most abundant and seemingly depth-sensitive Everglades wading bird, the White Ibis (Eudocimus albus). I implemented a 2-year experimental study in four replicated manmade wetlands with controlled water recession rates in order to determine the effects of proximate deep water (akin to canals) on fish prey concentrations in the sloughs, as water levels receded similarly to a natural Everglades dry season. I also calculated average daily wading bird densities with game cameras (Reconyx PC800 Hyperfire) using timelapse imagery over 60 days to determine when and where wading birds responded to changing prey concentrations. I completed an additional observational study on White Ibis and slough crayfish prey from the first year of data (2017). Crayfish make up the majority of the diet for nesting White Ibis, and literature has suggested crayfish are most abundant at slough depths much deeper than previously proposed foraging depth limitations for White Ibis. This study specifically compared recent determinations about crayfish movement dynamics in the ridge and slough system with White Ibis foraging behavior and depth limits. Results from the first experimental study suggest that canals might be an attractive refuge for relatively large prey fishes (> 3 cm SL) in sloughs, but it is uncertain if the fencing blocked all prey fish movement. The second observational study determined White Ibis foraging activity was primarily driven by a down-gradient crayfish flux from ridge to slough, with the majority of foraging activity occurring at much deeper slough depths than previously suggested water depth limitations for White Ibis. Results from both of these studies support the importance of preserving the ridgeslough landscape of the Everglades to sustain high prey availability for wading birds. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2018. / FAU Electronic Theses and Dissertations Collection

Oyster reefs are important estuarine ecosystems that provide habitat to many species including threatened and endangered wading birds and commercially important fishes and crabs. Infaunal organisms (i.e. small, aquatic animals that burrow in the sediment) are also supported by oyster reef habitats. Infaunal organisms are critical to marine food webs and are consumed by many important species that inhabit coastal estuaries. However, over the past century 85% of shellfish reef habitats have been lost, making restoration of these areas vital. Due to their important role in coastal food webs, infauna is hypothesized to be a strong indicator of habitat productivity to document the transition from a dead to a restored and living intertidal oyster reef. Research was conducted in Mosquito Lagoon of the northern Indian River Lagoon system. Three replicate samples were collected from 12 intertidal oyster reefs (four dead, four live, four restored). Samples were collected one-week pre-restoration and one month and six months post-restoration. Infauna was counted and sorted into six taxonomic categories: polychaetes, amphipods, isopods, gastropods, bivalves, and decapods. Reef infaunal abundance increased following restoration: restored reefs became more similar to live reefs one month following restoration. Six months after restoration restored reefs were also significantly different than dead reefs. Live reefs consistently had high infaunal abundance and dead reefs consistently had low abundance, while restored reefs were intermediate. These data suggest restored reefs are more productive than their dead counterparts, with restoration showing a positive trajectory to impact numerous infaunal species and their associated food webs.

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Rice not collected by harvesters and natural seeds are important foods for waterfowl. Estimation of abundance of these seeds is necessary for calculating waterfowl habitat conservation needs in the Louisiana Chenier Plain (LCP) and Texas Mid-Coast (TMC). My objectives were to quantify dry mass of rice and other seeds from August-November 2010, and estimate waterbird abundances on farmed and idle ricelands in these regions from December 2010-March 2011. Rice abundance in farmed ricelands ranged from 159.7 kg/ha (CV = 66.6%) to 1,014.0 kg/ha (CV = 8.3%). Natural seed abundance in idle ricelands ranged from 99.7 kg/ha (CV = 32.9%) to 957.4 kg/ha (CV = 17.2%). Greatest waterbird densities occurred in shallowly flooded (i.e., ¡Ü30 cm) disked ricelands (mean = 7.35 waterbirds/ha, 90%; CI = 2.37-19.70). Ratoon, disked, and shallowly flooded ricelands are important habitat for non-breeding waterbirds but variable estimates of seed and waterbird abundances warrant continuation of this study.