Ronnenberg Katrin, Strauß Egbert, Siebert Ursula
Institute for Terrestrial and Aquatic Wildlife Research, University of Veterinary Medicine Hannover, Foundation , Bischofsholer Damm 15, 30173, Hannover, Germany.
Hunting Association of Lower Saxony, Schopenhauerstraße 21, 30625, Hannover, Germany.
BMC Ecol. 2016 Sep 9;16(1):39. doi: 10.1186/s12898-016-0093-9.
The grey partridge (Perdix perdix) and the common pheasant (Phasianus colchicus) are galliform birds typical of arable lands in Central Europe and exhibit a partly dramatic negative population trend. In order to understand general habitat preferences we modelled grey partridge and common pheasant densities over the entire range of Lower Saxony. Spatially explicit developments in bird densities were modelled using spatially explicit trends of crop cultivation. Pheasant and grey partridge densities counted annually by over 8000 hunting district holders over 10 years in a range of 3.7 Mio ha constitute a unique dataset (wildlife survey of Lower Saxony). Data on main landscape groups, functional groups of agricultural crops (consisting of 9.5 million fields compiled by the Integrated Administration and Control System) and landscape features were aggregated to 420 municipalities. To model linear 8 or 10 year population trends (for common pheasant and grey partridge respectively) we use rho correlation coefficients of densities, but also rho coefficients of agricultural crops.
All models confirm a dramatic decline in population densities. The habitat model for the grey partridge shows avoidance of municipalities with a high proportion of woodland and water areas, but a preference for areas with a high proportion of winter grains and high crop diversity. The trend model confirms these findings with a linear positive effect of diversity on grey partridge population development. Similarly, the pheasant avoids wooded areas but showed some preference for municipalities with open water. The effect of maize was found to be positive at medium densities, but negative at very high proportions. Winter grains, landscape features and high crop diversity are favorable. The positive effect of winter grains and higher crop diversity is also supported by the trend model.
The results show the strong importance of diverse crop cultivation. Most incentives favor the cultivation of specific crops, which results in large areas of monocultures. The results confirm the importance of sustainable agricultural policies.
灰山鹑（Perdix perdix）和雉鸡（Phasianus colchicus）是中欧耕地典型的鸡形目鸟类，其种群数量呈部分显著的负增长趋势。为了解它们的一般栖息地偏好，我们对下萨克森州全境的灰山鹑和雉鸡密度进行了建模。利用作物种植的空间明确趋势对鸟类密度的空间明确变化进行建模。在370万公顷范围内，8000多名狩猎区持有者在10年里每年统计的雉鸡和灰山鹑密度构成了一个独特的数据集（下萨克森州野生动物调查）。关于主要景观组、农作物功能组（由综合行政控制系统编制的950万个田地组成）和景观特征的数据被汇总到420个市镇。为了模拟线性的8年或10年种群趋势（分别针对雉鸡和灰山鹑），我们使用了密度的rho相关系数，以及农作物的rho系数。
所有模型均证实种群密度急剧下降。灰山鹑的栖息地模型显示，它们会避开林地和水域比例高的市镇，但偏好冬季谷物比例高和作物多样性高的地区。趋势模型通过多样性对灰山鹑种群发展的线性正效应证实了这些发现。同样，雉鸡会避开林地，但对有开阔水域的市镇表现出一定偏好。发现玉米在中等密度时具有正效应，但在比例非常高时具有负效应。冬季谷物、景观特征和高作物多样性是有利的。趋势模型也支持冬季谷物和更高作物多样性的正效应。
结果表明多样化作物种植非常重要。大多数激励措施有利于特定作物的种植，这导致了大面积的单一栽培。结果证实了可持续农业政策的重要性。
