Nest survival of threatened Eurasian Curlew ( Numenius arquata ) breeding at low densities across a human-modified landscape
Nest survival of threatened Eurasian Curlew ( Numenius arquata ) breeding at low densities across a human-modified landscape
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受威胁的欧亚杓鹬（Numenius arquata）在人工改造景观中低密度繁殖的巢穴生存
作者：
Ewing H
采取有针对性的管理行动，提高关键的人口比例，有助于恢复稀有和局部种群，但越来越需要稳定或扭转以前常见和广泛的物种的下降。由于生产率不可持续地低，欧洲许多繁殖涉禽的数量正在下降，而旨在提高涉禽繁殖率的保护工具已被最有效地用于保护区内的半殖民物种。对在人类改造的景观中以低密度繁殖的涉禽物种进行有针对性的管理，例如迅速下降的欧亚CurlewNumenius arquata，可能更具挑战性。在这里，我们量化了杓鹬巢生存的变化，以探讨如何有针对性地管理，以提高这一关键组成部分的繁殖生产力。2019年至2021年期间，在英格兰东部布雷克兰的8个地点，每年监测多达80对欧亚杓鹬，其筑巢密度从<1对/平方公里到0.7对/平方公里不等。在草原和耕地为主的地点的136个巢中，大多数失败（86%）是由（主要是夜间）捕食引起的，所有孵化或捕食的巢（127）的平均孵化存活概率（PSI）为c。0.25.巢生存表现出很小的年度或季节性变化，但略有不同的网站之间，但是，这种空间变化并没有明确的管理条件或巢隐藏在这些网站。围栏，以排除哺乳动物巢捕食者可以有效的涉禽，但太少的欧亚杓鹬目前巢内围栏地区在布雷克兰产生可观察到的影响。在少数筑巢密度高的地点设置围栏可能会使研究区域内每年孵化的小鸡数量增加一倍，但可能需要采取景观规模的行动来减少捕食者对巢穴和小鸡的影响，以维持更广泛的农村地区的繁殖数量。
Targeted management actions to boost key demographic rates can help to restore rare and localized populations but are increasingly required to stabilize or reverse declines of formerly common and widespread species. Many breeding wader populations across Europe are declining because of unsustainably low rates of productivity, and the conservation tools designed to boost wader breeding productivity have been most effectively used for semi‐colonial species within protected areas. Targeted management for wader species that breed at low densities across human‐modified landscapes, such as the rapidly declining Eurasian CurlewNumenius arquata, is likely to be more challenging. Here, we quantify variation in Curlew nest survival to explore how management could be targeted to boost this key component of breeding productivity. Up to 80 pairs of Eurasian Curlew were monitored annually between 2019 and 2021 in eight locations across Breckland, eastern England, where nesting densities range from <1 toc0.7 pairs/km2. For 136 nests across grassland‐ and arable‐dominated sites, the majority of failures (86%) were caused by (primarily nocturnal) predation and the mean probability of surviving incubation (PSI) for all hatched or predated nests (127) wasc. 0.25. Nest survival showed little annual or seasonal variation but did vary slightly between sites; however, this spatial variation was not clearly related to management conditions or nest concealment at these sites. Fencing to exclude mammalian nest predators can be effective for waders, but too few Eurasian Curlews currently nest within fenced areas in Breckland to produce observable effects. Fencing the few sites with high nesting densities could potentially double the number of chicks hatched each year within the study area, but landscape‐scale actions to reduce predator impacts on nests and chicks are likely to be needed to maintain breeding numbers in the wider countryside.