Data from: Wind farms affect the occurrence, abundance and population trends of small passerine birds: the case of the Dupont's lark

1.The assessment of the effects of wind farms on bird populations is commonly based on collision fatality records. This could undervalue the effect of wind farms on small-sized birds. We evaluate the effect of wind turbines on occurrence, abundance and population trends of a threatened small passerine species, the Dupont's lark Chersophilus duponti. To our knowledge, this is one of the first studies addressing the effect of wind farms on population trends using time series data from multiple wind farms.

2.We estimated population trends by fitting a switching linear trend model with the software TRIM (Trend & Indices for Monitoring data). We used multiannual data surveys of five populations in the presence of wind farms and nine in their absence (2008–2016 period). Furthermore, we fitted a logistic and a negative binomial regression model to test the effect of wind farm proximity on species occurrence and abundance in 2016, respectively. We incorporated local connectivity and habitat availability estimates in both models as predictors.

3.Results showed a negative trend overall, but that was significantly more regressive in the presence of wind farms: 21.0% versus 5.8% average annual decline in the absence of wind farms.

4.Dupont's lark occurrence and abundance in 2016 were negatively affected by measures of population isolation and positively affected by the distance to wind farms.

5.These results highlight the negative effect of isolation and wind farm proximity on Dupont's lark population parameters. Taking into account the metapopulation structure exhibited by the species in the study area, this work established a 4.5 km threshold distance from wind farms, beyond which Dupont's lark populations should be unaffected.

6.Synthesis and applications. This work highlights the negative impact of wind farms on small-sized birds and provides a 4.5 km threshold distance that should be taken into account in the design of future wind energy projects. Moreover, we suggest an analytical approach based on population trends, species abundance and occurrence variation in relation to wind farms, useful for the assessment of wind farm impacts on small-sized birds.

1. 风电场对鸟类种群的影响评估通常基于碰撞致死记录，但该方法可能低估风电场对小型鸟类的影响。本研究以受威胁的小型雀形目物种——杜氏百灵（Dupont's lark, *Chersophilus duponti*）为研究对象，评估风力涡轮机对其出现率、种群丰度及种群动态的影响。据我们所知，本研究是首批利用多风电场的时间序列数据探究风电场对种群动态影响的研究之一。
2. 本研究借助TRIM（Trend & Indices for Monitoring data）软件拟合分段线性趋势模型，以估算种群动态。我们使用了2008-2016年间的多年调查数据，涵盖5个受风电场影响的种群以及9个未受风电设施影响的种群。此外，本研究分别构建逻辑回归模型与负二项回归模型，用以检验2016年时风电场邻近程度对该物种出现率与种群丰度的影响；同时将局地连通性与栖息地可获得性的评估值作为预测变量纳入两个模型中。
3. 研究结果显示，整体种群呈下降趋势，但在有风电场分布的区域，种群衰退趋势更为显著：有风电场区域的年均种群降幅达21.0%，而无风电设施区域的年均降幅仅为5.8%。
4. 2016年，杜氏百灵的出现率与种群丰度受到种群隔离程度指标的负面影响，同时随着与风电场距离的增加而显著提升。
5. 上述结果证实了种群隔离与风电场邻近程度对杜氏百灵种群参数的负面影响。结合研究区域内该物种的集合种群（metapopulation）结构特征，本研究确定了风电场与杜氏百灵种群间的4.5km阈值距离：当距离超过该阈值时，风电场不会对杜氏百灵种群产生影响。
6. 总结与应用：本研究明确了风电场对小型鸟类的负面影响，并提出了4.5km的阈值距离，该距离应在未来风电项目的规划设计中予以考量。此外，本研究提出了一种基于种群动态、物种丰度及与风电场相关的出现率变化的分析方法，该方法可用于评估风电场对小型鸟类的影响。