Avian predators in a meadow landscape: consequences of their occurrence for breeding open-area birds
Avian predators in a meadow landscape: consequences of their occurrence for breeding open-area birds
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草地景观中的鸟类捕食者：它们的出现对露天鸟类繁殖的影响
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发表时间：
2008
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影响因子：
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通讯作者：
M. Wassen
中科院分区：
文献类型：
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作者：
R. E. Vliet;E. Schuller;M. Wassen
我们研究了6种草甸鸟类（4种涉禽和2种鸣禽）的发生与鸟类捕食者（3种）巢位距离的关系。我们将我们的发现与这种鸟类捕食者巢穴所在的景观的开放程度联系起来。开放程度从非常开放到非常封闭不等，取决于景观中阻碍视野的景观元素的数量（开放的景观中没有或很少，而非常封闭的景观中完全被森林或建成区覆盖）。我们使用了一个包含荷兰Gelderland省草甸鸟类和食肉动物筑巢位置的数据集，允许我们对三种网格单元大小（100×100 m， 250×250 m和500×500 m）进行分析。结果表明，对于每个网格大小，所有草甸鸟类在开放景观中都表现出最高的筑巢密度。无论捕食者的巢穴位于开放还是封闭的景观中，在被占领的鸟类巢穴周围发现的密度都较低。草甸鸟类对远离捕食者巢穴的开阔景观的偏好表明，大的能见度使它们能够扫描捕食者并及时赶走它们，这是草甸鸟类选择筑巢地点的重要栖息地要求。它还表明，景观的开放性，独立于捕食者巢穴的存在，是选择筑巢地点的一个因素。相比之下，对于三分之二的鸟类捕食者，我们发现它们选择更封闭的景观筑巢，因为这些物种在林地和孤树等景观元素中筑巢，这使得景观更加封闭。对于第三种鸟类捕食者，网格细胞的大小可能太小，无法找到一致的结果，因为该物种的领土甚至比我们使用的最大网格细胞的大小还要大。
We examined the occurrence of six species of meadow birds (four wader species and two songbird species) in relation to the distance to the nest location of an avian predator (three species). We related our findings to the degree of openness of the landscape in which this avian predator nest was located. The degree of openness varied from very open to very closed, depending on the number of view-obstructing landscape elements in the landscape (none or very few in open ones, but completely covered with forest or built-up area in very closed landscapes). We used a dataset containing nesting locations of meadow birds and predators in the province of Gelderland, the Netherlands, allowing us to perform the analysis on three grid cell sizes (100×100 m, 250×250 m and 500×500 m). Our results show that, for each grid cell size, all meadow bird species showed highest nesting densities in open landscapes. Lowered densities were found around occupied nests of avian predators, irrespective whether the predator's nest was situated in an open or closed landscape. The preference of meadow birds for open landscapes away from predator's nests suggests that a large visibility, that allows them to scan for predators to be able to chase them away in time, is an important habitat requirement for meadow birds to select a nest site. It also suggests that openness of the landscape, independent from the presence of occupied predator's nests, is a factor in selecting a nest site. In contrast, for two out of three species of avian predator, we found that they chose more closed landscapes to nest because these species nest in landscape elements like wood lots and lone trees which make the landscape more closed by definition. For the third avian predator species, the grid cell size was probably too small to find a consistent result, as that species has territories larger than even the largest grid cell size we used.