Simmons Robert E, Kolberg Holger, Braby Rod, Erni Birgit
DST/NRF Centre of Excellence at the Percy FitzPatrick Institute of African Ornithology, University of Cape Town, Rondebosch, South Africa, 7701.
Directorate Scientific Services, Ministry of Environment and Tourism, Windhoek, Namibia.
Conserv Biol. 2015 Jun;29(3):877-87. doi: 10.1111/cobi.12493. Epub 2015 Apr 9.
Many long-distance migrating shorebird (i.e., sandpipers, plovers, flamingos, oystercatchers) populations are declining. Although regular shorebird monitoring programs exist worldwide, most estimates of shorebird population trends and sizes are poor or nonexistent. We built a state-space model to estimate shorebird population trends. Compared with more commonly used methods of trend estimation, state-space models are more mechanistic, allow for the separation of observation and state process, and can easily accommodate multivariate time series and nonlinear trends. We fitted the model to count data collected from 1990 to 2013 on 18 common shorebirds at the 2 largest coastal wetlands in southern Africa, Sandwich Harbour (a relatively pristine bay) and Walvis Bay (an international harbor), Namibia. Four of the 12 long-distance migrant species declined since 1990: Ruddy Turnstone (Arenaria interpres), Little Stint (Calidris minuta), Common Ringed Plover (Charadrius hiaticula), and Red Knot (Calidris canutus). Populations of resident species and short-distance migrants increased or were stable. Similar patterns at a key South African wetland suggest that shorebird populations migrating to southern Africa are declining in line with the global decline, but local conditions in southern Africa's largest wetlands are not contributing to these declines. State-space models provide estimates of population levels and trends and could be used widely to improve the current state of water bird estimates.
许多远距离迁徙的滨鸟（如矶鹬、鸻、火烈鸟、蛎鹬）种群数量正在减少。尽管全球存在常规的滨鸟监测项目，但大多数对滨鸟种群趋势和规模的估计都不准确或根本不存在。我们构建了一个状态空间模型来估计滨鸟种群趋势。与更常用的趋势估计方法相比，状态空间模型更具机械性，允许分离观测和状态过程，并且能够轻松处理多元时间序列和非线性趋势。我们将该模型应用于1990年至2013年期间在纳米比亚南部非洲两个最大的沿海湿地——三明治港（一个相对原始的海湾）和沃尔维斯湾（一个国际港口）收集的18种常见滨鸟的计数数据。自1990年以来，12种远距离迁徙物种中有4种数量减少：翻石鹬（Arenaria interpres）、小滨鹬（Calidris minuta）、环颈鸻（Charadrius hiaticula）和红腹滨鹬（Calidris canutus）。留鸟物种和短距离迁徙物种的数量增加或保持稳定。南非一个关键湿地的类似模式表明，迁徙到南部非洲的滨鸟种群数量正在随着全球数量下降而减少，但南部非洲最大湿地的当地条件并非导致这些减少的原因。状态空间模型提供了种群数量水平和趋势的估计，可广泛用于改善当前水鸟估计的现状。
