Data from: Using ricelands to provide temporary shorebird habitat during migration

To help mitigate large wetland losses in California, The Nature Conservancy launched a dynamic conservation incentive program to create temporary wetland habitats in harvested and fallow rice fields for shorebirds migrating along the Pacific Flyway. Farmers were invited to participate in a reverse auction bidding process and winning bids were selected based on their cost and potential to provide high quality shorebird habitat. This was done in 2014 and 2015, for separate enrollment periods that overlapped with spring and fall migration, both before and after the traditional post-harvest flooding period. To assess the success of the program we monitored shorebird use of fields that were enrolled (treatments), and others that were subject to typical rice farm management (controls). To put these observations in context, we used satellites to simultaneously monitor the extent of shallow-water habitat across the ~215,000 hectares of ricelands in the area. Results showed that providing habitat during migration, when it is typically unavailable in rice fields, yielded the largest average shorebird densities ever reported for agriculture in the region. Treatment fields had significantly greater shorebird density, richness and diversity than control fields in both spring and fall (especially September – early October, and late March – early April), but in fall the difference was greater. Shorebird responses to habitat provisioning, and regional habitat conditions, were variable from year to year, and highly dynamic within a given season. Overall, shorebirds densities were found to be negatively related to the total amount of flooded habitat in the rice landscape. Factors that affected habitat availability included allocation schedules of water deliveries from reservoirs, and rainfall patterns, both of which were influenced by drought. Collectively, these results suggest that appropriately managed agricultural lands have great potential to provide high value habitat for shorebirds during times of habitat deficit, including migration, and that fall may be a particularly impactful time to create additional habitat. Migratory species face great challenges due to the climate change, conversion of historical stopover sites, and other factors, but dynamic conservation programs offer promise that, at least in certain instances, their needs can still be met.

为缓解加利福尼亚州湿地大面积流失的困境，大自然保护协会（The Nature Conservancy）推出一项动态保护激励计划，为沿太平洋迁飞路线（Pacific Flyway）迁徙的滨鸟在已收割及休耕的稻田中打造临时湿地生境。主办方邀请农户参与反向拍卖竞标流程，中标方案将综合考量竞标成本与提供优质滨鸟生境的潜力。该计划于2014年与2015年实施，设置了两个独立的登记时段，分别对应春季与秋季迁徙季，且两个时段均涵盖了传统收获后淹水期的前后阶段。为评估该计划的实施成效，我们对参与计划的稻田（处理组）以及采用常规稻田管理模式的稻田（对照组）的滨鸟利用情况开展了监测。为便于解读观测结果，我们同步借助卫星对该区域约21.5万公顷稻田种植区内的浅水生境覆盖范围进行了监测。研究结果显示，在迁徙季——此时稻田通常无法提供适宜生境——搭建临时生境，使该区域农业生境中的滨鸟平均密度达到了有记录以来的最高水平。无论春季还是秋季，处理组稻田的滨鸟密度、物种丰富度与物种多样性均显著高于对照组，尤其在9月上旬至10月初、3月下旬至4月初这两个时段，且秋季的组间差异更为显著。滨鸟对生境营造的响应以及区域生境状况在不同年份间存在波动，且在单个迁徙季内也呈现出高度动态的变化特征。整体而言，研究发现滨鸟密度与稻田景观内的淹水生境总面积呈负相关关系。影响生境可获得性的因素包括水库输水调度计划与降雨模式，二者均受干旱条件的影响。综合来看，上述结果表明，在生境匮乏时期（包括迁徙季），经过合理管护的农业用地可为滨鸟提供高价值生境，具备巨大潜力；而秋季或许是打造额外生境的尤为关键的时段。迁徙物种正面临气候变化、历史中途停歇地被开发改造以及其他诸多挑战，但动态保护计划为应对这些问题带来了希望——至少在某些特定场景下，迁徙物种的生存需求仍可得到满足。