Mercury (Hg) is a global pollutant that affects songbird populations across a variety of ecosystems following conversion to methylmercury (MeHg)—a form of Hg with high potential for bioaccumulation and bioavailability. The amount of bioavailable MeHg in an ecosystem is a function of the amount of total Hg present as well as Hg methylation rates, which vary across the landscape in space and time, and trophic transfer. Using songbirds as an indicator of MeHg bioavailability in terrestrial ecosystems, we evaluated the role of habitat, climate, and trophic level in dictating MeHg exposure risk across a variety of ecosystems. To achieve this objective, 2243 blood Hg samples were collected from 81 passerine and near-passerine species in New York State, USA, spanning 10 different sampling regions from Long Island to western New York. Using a general linear mixed modeling framework that accounted for regional variation in sampling species composition, we found that wetland habitat area within 100 m of capture location, 50-year average of summer maximum temperatures, and trophic position inferred using stable isotope analysis were all correlated with songbird blood Hg concentrations statewide. Moreover, these patterns had a large degree of spatial variability suggesting that the drivers of MeHg bioavailability differed significantly across the state. Mercury deposition, land cover, and climate are all expected to change throughout the northeastern United States in the coming decades. Terrestrial MeHg bioavailability will likely respond to these changes. Focused research and monitoring efforts will be critical to understand how exposure risk responds to global environmental change across the landscape.

汞（Hg）是一种全球性污染物，在转化为甲基汞（MeHg）后会影响整个生态系统中的鸣禽种群，甲基汞（MeHg）是一种具有高生物蓄积性和生物利用度潜力的汞。生态系统中可生物利用的MeHg的量是存在的总Hg量以及Hg甲基化率的函数，Hg甲基化率在空间，时间和营养传递方面随景观变化。使用鸣禽作为陆地生态系统中MeHg生物利用度的指标，我们评估了栖息地，气候和营养水平在决定各种生态系统中MeHg暴露风险中的作用。为了实现这一目标，从美国长岛到纽约州西部的10个不同采样区域，从美国纽约州的81种雀形目和近雀形目物种中收集了2243份血汞。使用考虑采样物种组成区域差异的通用线性混合建模框架，我们发现捕获位置100 m以内的湿地栖息地面积，夏季最高温度的50年平均值以及通过稳定同位素分析推断的营养位置均相关全州范围内的鸣禽血中汞浓度 此外，这些模式具有很大的空间变异性，表明MeHg生物利用度的驱动因素在整个州之间存在显着差异。预计在未来几十年中，整个美国东北部的汞沉积，土地覆盖和气候都会发生变化。陆地MeHg的生物利用度可能会响应这些变化。