Lesser Yellowlegs location data describing the occurrence of birds within harvest zones in the Caribbean and South America

Shorebirds have experienced a precipitous reduction in abundance over the past four decades. While some threats to shorebirds are widespread (e.g. habitat alteration), others are regional and may affect specific populations. Lesser Yellowlegs (Tringa flavipes) are long-distance migrants that breed across the North American boreal biome and have declined in abundance by 60-80% since the 1970s. The documented harvest of Lesser Yellowlegs in the Caribbean and northeastern South America during southward migration is a possible limiting factor for the species, but it is unknown to what extent birds from different breeding origins may be affected. To address the question of differential occurrence in harvest zones during southward migration, we used PinPoint GPS Argos transmitters to track the southward migrations of 85 adult Lesser Yellowlegs from across the species' breeding range and 80° of longitude from Anchorage, Alaska, USA to the Mingan Archipelago, Quebec, Canada. We classified migratory locations as inside or outside three zones with high levels of harvest (Caribbean, coastal Guianas, and coastal Brazil) and then fit generalized additive mixed models to estimate the probability of occurrence of Lesser Yellowlegs in harvest zones according to their breeding origin. Individuals from the Eastern Canada population had a higher probability of occurrence within one or more harvest zones and remained in those zones longer than individuals breeding in Alaska and western Canada. Linear regressions also suggested that longitude of the breeding origin is an important predictor of occurrence in harvest zones during southward migration. Lastly, our findings, combined with other sources of evidence, suggest that current estimated harvest rates may exceed sustainable limits for Lesser Yellowlegs, which warrants further investigation.

近四十年来，鸻鹬类（Shorebirds）的种群丰度经历了急剧下降。尽管部分威胁因素对鸻鹬类具有普遍性（如栖息地改变），但另有一些威胁具有区域性，可能仅影响特定种群。小黄脚鹬（Lesser Yellowlegs，学名Tringa flavipes）为长途迁徙鸟类，繁殖于北美寒温带生物群区，自20世纪70年代以来种群丰度已下降60%至80%。有记录显示，在向南迁徙期间，加勒比海及南美东北部区域存在小黄脚鹬的捕猎行为，这可能是该物种种群受限的潜在因素，但目前尚不明确不同繁殖起源的种群受影响的程度。为解答小黄脚鹬在向南迁徙期间于捕猎区的分布差异这一科学问题，本研究使用PinPoint GPS Argos发射器，对覆盖该物种种群繁殖范围、跨度达80个经度的85只成年小黄脚鹬的向南迁徙过程进行追踪，追踪范围从美国阿拉斯加州安克雷奇延伸至加拿大魁北克省明甘群岛。研究人员将迁徙定位点划分为三个高捕猎强度区域（加勒比海、圭亚那沿海及巴西沿海）内或外，并构建广义加性混合模型（generalized additive mixed models），以估算不同繁殖起源的小黄脚鹬出现在捕猎区的概率。相较于在阿拉斯加及加拿大西部繁殖的个体，加拿大东部种群的小黄脚鹬在一个或多个捕猎区内出现的概率更高，且在捕猎区停留的时间更长。线性回归分析同样表明，繁殖起源的经度是影响小黄脚鹬在向南迁徙期间进入捕猎区的重要预测因子。综上，本研究结果结合其他证据显示，当前估算的小黄脚鹬捕猎率可能已超出其种群可持续极限，这一发现亟需开展进一步研究。