Evaluating if abundance and behavior of shorebird species are related to restoration and habitat at Whiskey Island and Caminada Headland, Louisiana from 2012 to 2020

Barrier islands provide resources and ecological services that are integral to economic and environmental interests, such as protection of coastal infrastructure and providing habitat for wildlife. Over time, barrier islands may become eroded and experience land loss, which require management actions to restore island integrity. The process of restoring barrier islands can create new habitats but also alter existing habitats, which can impact the organisms depending on coastal habitats, such as the Endangered Species Act-listed (ESA) Piping Plover (Charadrius melodus) and Red Knot (Calidris canutus). Consequently, we aimed to understand the abundance and behavioral responses from a suite of shorebird species, including American Oystercatcher (Haematopus palliatus), Red Knot, Piping Plover, Snowy Plover (Charadrius nivosus), and Wilson’s Plover (Charadrius wilsonia), to restoration and habitat factors at two restored sites in coastal Louisiana, Whiskey Island and Caminada Headland, from 2012 to 2020. We combined observational data from birds with numerous geospatial predictor variables into a machine learning approach to develop response plots to investigate how birds use coastal habitat with respect to restoration activities at Whiskey Island and Caminada Headland, Louisiana from 2012 to 2020. For each species, we quantified the abundance and behavior (breeding, foraging, leisure) of each individual, which served as response variables in boosted regression tree models, and determined the importance of predictor variables, such as restoration phase, habitat class, inundation class, distance to water, and other remotely or field collected variables from Whiskey Island and Caminada Headland. We ran at least three models for each species, which included non-breeding abundance with a Poisson distribution, foraging behavior with a binomial distribution, and leisure behavior with a binomial distribution. For American Oystercatcher (only occurring in reasonable sample sizes at Whiskey Island) and Wilson’s Plover, we also ran models for breeding abundance with a Poisson distribution and breeding behavior with a binomial distribution.

障壁岛（barrier island）可为经济与生态利益提供不可或缺的资源与生态系统服务，例如保护海岸基础设施、为野生动物提供栖息地。随着时间推移，障壁岛可能发生侵蚀与陆域流失，因此需要开展修复管理措施以恢复其岛屿完整性。障壁岛修复过程既能创造新生境，也会改变原有生境，进而对依赖海岸生境的生物造成影响，例如列入《濒危物种法案（Endangered Species Act，ESA）》的笛鸻（Piping Plover，Charadrius melodus）与红腹滨鹬（Red Knot，Calidris canutus）。因此，本研究旨在探明2012—2020年间，路易斯安那州沿海两处修复场址——威士忌岛（Whiskey Island）与卡米纳德岬（Caminada Headland）——的多种鸻鹬类物种对修复活动与生境因子的丰度与行为响应。涉及物种包括美洲蛎鹬（American Oystercatcher，Haematopus palliatus）、红腹滨鹬、笛鸻、雪鸻（Snowy Plover，Charadrius nivosus）以及威尔逊鸻（Wilson’s Plover，Charadrius wilsonia）。本研究将鸟类观测数据与大量地理空间预测变量相结合，采用机器学习方法生成响应绘图，以探究2012—2020年间路易斯安那州威士忌岛与卡米纳德岬的鸟类如何依据修复活动利用海岸生境。针对每一物种，本研究对个体的丰度及行为（繁殖、觅食、休憩）进行量化，将其作为提升回归树模型的响应变量，并分析各预测变量的重要性，其中预测变量包括修复阶段、生境类型、淹没等级、距水体距离，以及从威士忌岛与卡米纳德岬通过遥感或野外采集得到的其他变量。针对每一物种，本研究至少构建三类模型：基于泊松分布（Poisson distribution）的非繁殖期丰度模型、基于二项分布（binomial distribution）的觅食行为模型，以及基于二项分布的休憩行为模型。针对美洲蛎鹬（仅在威士忌岛获取到可接受的样本量）与威尔逊鸻，本研究额外构建了基于泊松分布的繁殖期丰度模型，以及基于二项分布的繁殖行为模型。