Is the ‘bat population’ an operational concept for statutory species conservation?

Abstract

In the European Union (EU), all bat species are legally protected by the Habitats Directive (HD). Especially the goal of keeping or restoring a favourable conservation status for protected species and habitats is an outstanding innovation in the law of nature conservation. The Directive does not only focus on rare species close to extinction, but has the goal of viable populations for all species included in the pertinent annexes. However, most bat populations are still far away from reaching this goal, which leads to the question why the Habitats Directive may have failed to achieve its objective.We argue that the pluralism of definitions of the concept of ‘population’ is a major problem in the application of the Directive. Concerning bats, several population definitions are possible that fit biological aims as well as aims of legal protection. But without clear assignment which definition should be used in the application of nature conservation law, the pluralism of the population definition offers the possibility of arbitrary use, and with it the failure of bat conservation. In consequence, we describe different population definitions and give suggestions to avoid arbitrary delimitation. When applying species protection law, the population must be specified through ecological parameters rather than merely through statistical approaches. In case of migrating bats, we found that the objectives of the HD can only be achieved with individual-based approaches. Population-based protection is doomed to failure because of the lack of knowledge about meaningful population delimitation. Thus, strong EU-wide effort is necessary to completely implement legal bat protection.

Keywords

• European Habitats Directive
• Population definition
• Ecological impact assessment