Data from: Butterfly density and behaviour in uncut hay meadow strips: behavioral ecological consequences of an agri-environmental scheme

Sparing zones from mowing has been proposed, and applied, to improve local conditions for survival and reproduction of insects in hay meadows. However, little is known about the efficiency of refuge zones and the consequences for local populations. We studied population densities of butterflies before and after mowing in the refuge zone of 15 meadows in 2009 and 2011. We also studied the behaviour of the meadow brown (Maniola jurtina) comparing nectar use, interactions and flights in the refuge zone before and after mowing. Densities of grassland butterflies in this zone doubled on average after mowing. The density of females of M. jurtina increased on average fourfold, while males showed a more modest increase. In line with the idea of increased scramble competition in the refuge zone after mowing, M. jurtina increased the time spent on nectar feeding, the preferred nectar source was visited more frequently, and females made more use of non-preferred nectar sources. Maniola jurtina did not interact more with conspecifics after mowing, but interactions lasted longer. Flight tracks did not change in linearity, but were faster and shorter after mowing. After mowing, only a part of the local grassland butterflies moved to the uncut refuge zone. The resulting concentration effect alters the time allocated to different activities, nectar use and movements. These aspects have been largely ignored for agri-environmental schemes and grassland management in nature reserves and raise questions about optimal quantities and quality of uncut refuge sites for efficient conservation of grassland arthropods in agricultural landscapes.

在干草甸中保留免割区域的做法，已被提出并付诸实践，旨在改善昆虫的存活与繁殖生境条件。然而，目前对这类庇护区（refuge zone）的实施成效及其对当地昆虫种群的影响仍知之甚少。本研究于2009年与2011年，针对15处干草甸的庇护区，调查了割草前后的蝶类种群密度。此外，本研究还以草地褐眼蝶（Maniola jurtina）为研究对象，对比分析了割草前后其在庇护区内的访花行为、种内互作与飞行活动。该区域内的草原蝶类种群密度在割草后平均提升了一倍。草地褐眼蝶的雌蝶种群密度平均增长至原来的四倍，而雄蝶的增幅则相对平缓。这与割草后庇护区内争夺型种内竞争（scramble competition）加剧的假说相符：草地褐眼蝶延长了访花取食的时长，对偏好蜜源的访问频率显著提升，雌蝶则更多利用非偏好蜜源资源。割草后，草地褐眼蝶与同种个体的互作频次并未增加，但单次互作的持续时间有所延长。其飞行轨迹的线性度未发生变化，但割草后飞行速度更快、飞行路径更短。割草后，仅有部分本地草原蝶类迁入未被割除的庇护区。由此产生的种群聚集效应，改变了蝶类用于各类活动的时间分配、访花行为与飞行活动模式。上述诸多环节在自然保护区的农业环境方案与草原管理实践中长期被忽视，这也引发了相关疑问：在农业景观中，若要高效保护草原节肢动物，未割除的庇护区的最优规模与质量标准应当如何设定？