Duckworth Gregory D, Altwegg Res
Statistics in Ecology, Environment and Conservation Department of Statistical Sciences University of Cape Town Cape Town South Africa.
African Climate and Development Initiative University of Cape Town Rondebosch Cape Town South Africa.
Divers Distrib. 2018 Aug;24(8):1083-1091. doi: 10.1111/ddi.12756. Epub 2018 Apr 30.
Protected areas are key conservation tools intended to increase biodiversity and reduce extinction risks of species and populations. However, the degree to which protected areas achieve their conservation goals is generally unknown for many protected areas worldwide. We assess the effect of protected areas on the abundance of 196 common, resident bird species. If protected areas were beneficial to avian biodiversity, we expect landscapes with a higher proportion of protected areas will have higher densities of species compared to landscapes with no protection.
Greater Gauteng region, South Africa.
We analysed bird survey data collected over regular grid cells across the study area. We estimated bird abundance in relation to the proportion of a grid cell that was protected with the Royle-Nichols model and fitted the model once for each of the species. We examined variation in estimated abundance as a function of avian guild (defined by the type of food a species preferentially ate and its foraging mode) with a regression tree analysis.
Abundance was significantly positively related to the proportion of protected areas in grid cells for 26% of the species, significantly negatively related in 15%, and not significantly related in 59% species. We found three distinct guild groups which differed in their average abundance, after accounting for associated variance. Group 1 consisted of guilds frugivores, ground-feeders, hawkers, predators, and vegivores and average abundance was strongly positively related to the proportion of protected areas. Group 2 included granivores, and average abundance was strongly negatively related to proportion of protected areas. Group 3 included gleaners only, and average abundance was not related to proportion of protected areas.
We conclude that the network of protected areas within the greater Gauteng region sustained relatively higher abundances of common birds and thus perform an important conservation role.
保护区是旨在增加生物多样性并降低物种和种群灭绝风险的关键保护工具。然而，全球许多保护区实现其保护目标的程度通常尚不清楚。我们评估了保护区对196种常见留鸟物种数量的影响。如果保护区对鸟类生物多样性有益，我们预计与没有保护措施的景观相比，保护区比例更高的景观将具有更高的物种密度。
南非豪登大区。
我们分析了在整个研究区域的规则网格单元上收集的鸟类调查数据。我们使用罗伊尔 - 尼科尔斯模型估计与网格单元中受保护比例相关的鸟类数量，并为每个物种拟合一次该模型。我们通过回归树分析研究估计数量的变化作为鸟类群落（由物种优先食用的食物类型及其觅食方式定义）的函数。
26%的物种数量与网格单元中保护区的比例呈显著正相关，15%呈显著负相关，59%无显著相关。在考虑相关方差后，我们发现了三个不同的群落组，它们的平均数量有所不同。第1组包括食果动物、地面觅食者、小贩、捕食者和食草动物群落，平均数量与保护区比例呈强烈正相关。第2组包括食谷动物，平均数量与保护区比例呈强烈负相关。第3组仅包括食腐动物，平均数量与保护区比例无关。
我们得出结论，豪登大区的保护区网络维持了相对较高数量的常见鸟类，因此发挥了重要的保护作用。
