Mokotjomela Thabiso Michael, Vukeya Loyd Rodney, Pamla Lwandiso, Scott Zimbini
South Africa National Biodiversity Institute Free State National Botanical Garden Bloemfontein South Africa.
School of Life Sciences University of KwaZulu-Natal Pietermaritzburg South Africa.
Ecol Evol. 2023 Oct 20;13(10):e10452. doi: 10.1002/ece3.10452. eCollection 2023 Oct.
In this study, we documented the diversity of bird species in the Eastern Cape coastal nature reserves (i.e., Hluleka, Dwesa, Silaka and Mkhambati nature reserves), and determined the potential role of each bird species in habitat maintenance using two functional traits (i.e., body mass and feeding mode) as the function's proxy. We applied the timed species count approach during bird observations, coupled with drive-by surveys to maximise spatial coverage of each nature reserve over four years. To evaluate functional diversity, bird species were classified based on functional traits such as the adult body, and their potential ecological role derived from their feeding mode and habitat associations. Over 864 h, we accumulated 818 bird records containing 178 different bird species that were classified into 58 families with 32 species occurring in all nature reserves. Shannon-Wiener Diversity Indices showed very high overall species diversity across the nature reserves ( > 3.5) with no differences detected across sites. Although no significant correlations between vegetation changes measured through Normalised Difference vegetation Index (NDVI) in each nature reserve and the number of bird records, forest bird species were dominant (42.1%; = 178) throughout years of observation and diversity remained high ( > 3.5). Bird species abundance only increased significantly across all nature reserves during 2018-2019. All four nature reserves had a similar distribution of bird functional traits with both high functional richness (FRic = 1), and divergence (FDiv = 0.8) and moderate evenness (FEve = 0.4). Multiple Correspondence Analysis (MCA) demonstrated a positive correlation between bird sizes and functions with large birds mainly associated with predators and carrion. Small birds and medium birds had a similar composition of species in terms of functionality being seed dispersers across the nature reserves. A significant effect that insectivores and carrions displayed in MCA plots, suggest the availability of indirect pollination services. Despite extreme drought conditions across the country in 2019, NDVI levels remained largely consistent over time in these four reserves; and thus, they offer important refuge for birds during extreme climatic conditions such as drought.
在本研究中，我们记录了东开普省沿海自然保护区（即赫卢莱卡、德韦萨、西拉卡和姆坎巴蒂自然保护区）鸟类物种的多样性，并使用两个功能性状（即体重和取食方式）作为函数代理，确定了每种鸟类在栖息地维持中的潜在作用。在鸟类观察期间，我们采用定时物种计数方法，并结合驾车调查，以在四年内最大限度地扩大每个自然保护区的空间覆盖范围。为了评估功能多样性，根据成年体型等功能性状对鸟类物种进行分类，并根据它们的取食方式和栖息地关联确定其潜在的生态作用。在超过864小时的时间里，我们积累了818条鸟类记录，包含178种不同的鸟类，这些鸟类被分为58个科，其中32种出现在所有自然保护区。香农-维纳多样性指数显示，各自然保护区的总体物种多样性非常高（>3.5），各地点之间未检测到差异。尽管通过各自然保护区的归一化植被指数（NDVI）测量的植被变化与鸟类记录数量之间没有显著相关性，但在整个观察年份中，森林鸟类物种占主导地位（42.1%；n=178），多样性仍然很高（>3.5）。鸟类物种丰富度仅在2018 - 2019年期间在所有自然保护区显著增加。所有四个自然保护区的鸟类功能性状分布相似，功能丰富度（FRic = 1）、离散度（FDiv = 0.8）都很高，均匀度（FEve = 0.4）适中。多重对应分析（MCA）表明鸟类大小与功能之间存在正相关，大型鸟类主要与捕食者和腐肉相关。小型鸟类和中型鸟类在功能方面具有相似的物种组成，它们在各自然保护区都是种子传播者。食虫动物和食腐动物在MCA图中显示出显著影响，表明存在间接授粉服务。尽管2019年全国遭遇极端干旱条件，但这四个保护区的NDVI水平随时间基本保持一致；因此，它们在干旱等极端气候条件下为鸟类提供了重要的避难所。
