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Permanent URI for this collectionhttps://hdl.handle.net/1969.6/86486
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Browsing publications by Author "Chastant, Jennifer E."
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Item Nesting substrate and water-level fluctuations influence wading bird nesting patterns in a large shallow eutrophic lake(Springer International Publishing Switzerland, 2016-10-21) Chastant, Jennifer E.; Gawlik, Dale E.; Petersen, Michelle L.Water-level fluctuations determine the ecological function of shallow lakes and wetlands. Wading birds (Pelecaniformes and Ciconiiformes) are reliable indicators of the biotic conditions at multiple trophic levels, thereby reflecting an ecosystem response to water-level changes. We used a historic nesting record dating back to 1977 and an informationtheoretic approach to identify environmental factors that were most important for predicting the number of wading bird nests at Lake Okeechobee, a highly managed reservoir in Florida. The three top models accounted for 71% of the Akaike weight. Model variables included area of willow (Salix spp.) for nesting substrate, maximum depth of the lake on January 1, and foraging habitat availability over the nesting season. Collectively, the results suggest that the number of nests was greatest when area of nesting substrate was high and water levels were moderate (3.9–4.4 m). Nesting substrate was greatest when water levels fell below 3.9 m at least once every three years. Nest numbers dropped when either nesting substrate or foraging habitat was limited. This study identifies key hydrological parameters that support large populations of breeding wading birds and thus promote healthy, functioning wetland ecosystems.Item Water Level Fluctuations Influence Wading Bird Prey Availability and Nesting in a Subtropical Lake Ecosystem(The Waterbird Society, 2018-03-01) Chastant, Jennifer E.; Gawlik, Dale E.Food availability affects the reproductive success of animal populations. However, food availability includes both prey abundance and its accessibility, which are regulated by different environmental processes. The match-mismatch hypothesis links reproductive success to annual variability in food availability, but the threshold hypothesis suggests that changes in prey abundance can reduce or intensify the effects of a mismatch event. From January-June 2011-2013, food availability and wading bird (Pelecaniformes) reproduction were measured amidst different environmental conditions at Lake Okeechobee, Florida, USA. Mean prey density was 165 ± 21 prey/m2 (2011), 87 ± 7 prey/m2 (2012), and 104 ± 9 prey/m2 (2013) while 34% (2011), 36% (2012), and 77% (2013) of the landscape became available for foraging. Two generalized linear mixed models were constructed to quantify the relationship between fledging success and total productivity using prey density and foraging habitat availability as independent variables. The interaction of prey density and habitat availability was significant and positive in both models. Fledging success and total productivity increased with increasing prey density, the effects of which were more pronounced when habitat availability was low. Saturation thresholds existed for both fledging success (147 prey/m2) and total productivity (189 prey/m2), above which high concentrations of prey could sustain nesting when habitat availability was low