Center for Conservation Biology, College of William and Mary, Williamsburg, VA, United States of America.
Wildlife Resources Division, Georgia Department of Natural Resources, Non-Game Conservation Section, Brunswick, Georgie, United States of America.
PLoS One. 2023 Feb 13;18(2):e0281535. doi: 10.1371/journal.pone.0281535. eCollection 2023.
Bird species that are restricted to tidal marshes during one or all of their life stages are under increasing pressure from sea-level rise. To date, most of the research focused on this group has been conducted during the breeding season despite the fact that more than half of the annual cycle is spent on wintering grounds and the high likelihood that the winter period is the most critical time for adult survival. We used a double-pass rope-drag technique to estimate the winter abundance of sharp-tailed sparrows (Ammospiza nelson and A. caudacutus collectively), seaside sparrows (A. maritimus) and marsh wrens (Cistothorus palustris) within tidal marshes of Virginia along 102 60X250 m transects between January and March, 2014. We used the first pass to remove birds from the transect and the second pass was used to estimate detection probabilities. The technique was highly effective producing detection rates of 98% for sharp-tailed sparrows, 95% for seaside sparrows, and 91% for marsh wrens. We conducted three rounds of surveys and found that species-specific detection rates were comparable when we restricted our analyses to two survey rounds. Availability and abundance estimates deviated to a greater degree than detection rates when restricting data to that collected during only two rounds but confidence intervals overlapped for all three taxa, regardless of which two survey periods were used for the comparison. However, results were less precise when we restricted our analyses to two of three rounds with confidence intervals averaging 13%, 45%, and 14% larger for detection, availability, and abundance respectively. The double-pass rope-drag technique provides an effective, unbiased sampling technique to estimate winter songbird abundance in saltmarsh habitat provided that at least two rounds are used and increasing the number of survey rounds will result in more precise estimates.
在一个或所有生命阶段都局限于潮汐沼泽的鸟类物种正受到海平面上升的越来越大的压力。迄今为止，尽管超过一半的年周期都花在越冬地，并且冬季时期极有可能是成年生存的最关键时期，但对这一群体的大多数研究都是在繁殖季节进行的。我们使用双通绳索拖动技术，在 2014 年 1 月至 3 月期间，对弗吉尼亚州潮汐沼泽中的尖尾麻雀（Ammospiza nelson 和 A. caudacutus 统称）、海滨麻雀（A. maritimus）和沼泽鹪鹩（Cistothorus palustris）的冬季数量进行了估计，该技术使用了 102 条 60X250 米的样带。我们使用第一次通过来清除样带上的鸟类，第二次通过用于估计检测概率。该技术非常有效，产生了 98%的尖尾麻雀、95%的海滨麻雀和 91%的沼泽鹪鹩的检测率。我们进行了三轮调查，发现当我们将分析仅限于两轮调查时，物种特异性的检测率是可比的。当将数据限制在仅两轮收集的数据时，可用性和丰度估计值与检测率相差更大，但置信区间重叠，所有三个分类群都存在，无论比较使用了哪两个调查期。然而，当我们将分析限制在三轮中的两轮时，结果就不太精确了，置信区间平均分别增加了 13%、45%和 14%用于检测、可用性和丰度。双通绳索拖动技术是一种有效的、无偏的采样技术，可用于估计盐沼栖息地中冬季鸣禽的数量，前提是至少使用两轮，并且增加调查轮次将导致更精确的估计。
