Tracking butterflies for effective conservation Chris A.M. van Swaay Thesis committee Promoters Prof. Dr M.F. Wallis de Vries Special Professor of Insect Ecology and Conservation Wageningen University Prof. Dr M. Dicke Professor of Entomology Wageningen University Other members Prof. Dr F. Berendse, Wageningen University Prof. Dr J.C. Biesmeijer, University of Amsterdam Prof. Dr J.M. van Groenendael, Radboud University Nijmegen Prof. Dr H. Van Dyck, Université Catholique de Louvain, Belgium Tracking butterflies for effective conservation Chris A.M. van Swaay Thesis submitted in fulfilment of the requirements for the degree of doctor at Wageningen University by the authority of the Rector Magnificus Prof. Dr M.J. Kropff, in the presence of the Thesis Committee appointed by the Academic Board to be defended in public on Friday 31 October 2014 at 4 p.m. in the Aula. 3 C.A.M. van Swaay Tracking butterflies for effective conservation 218 pages. PhD thesis, Wageningen University, Wageningen, NL (2014) With references, with summaries in Dutch and English ISBN 978-94-6173-998-8 4 Content 1. General introduction .......................................................................................... 7 Part I: Tracking changes in butterfly distribution ................................................. 19 2. An Assessment of the Changes in Butterfly Abundance in The Netherlands during the 20th Century ....................................................................................... 21 3. A new methodology for compiling national Red Lists applied to butterflies (Lepidoptera, Rhopalocera) in Flanders (N-Belgium) and the Netherlands ........... 31 4. Metapopulation dynamics in the butterfly Hipparchia semele changed decades before occupancy declined in the Netherlands. ................................................... 43 Part II: Monitoring trends in butterfly abundance ................................................. 57 5. Butterfly monitoring in Europe: Methods, applications and perspectives ......... 59 6. Monitoring butterflies in the Netherlands: how to get unbiased indices ............ 71 7. Developing a butterfly indicator to assess changes in Europe's biodiversity ......79 8. Differences in the climate debts of birds and butterflies at continental scale ... 89 Part III: Towards effective Butterfly Conservation .................................................97 9. The relationship between butterflies and environmental indicator values: A tool for conservation in a changing landscape ............................................................ 99 10. Biotope use and trends of European butterflies ............................................ 113 11. Prime Butterfly Areas of Europe: An initial selection of priority sites for conservation ...................................................................................................... 135 12. Applying IUCN criteria to invertebrates: How red is the Red List of European butterflies? ......................................................................................................... 145 13. Synthesis ...................................................................................................... 159 References ......................................................................................................... 177 Summary ........................................................................................................... 195 Samenvatting .................................................................................................... 197 Curriculum vitae ................................................................................................ 199 Publications ...................................................................................................... 200 5 6 1. General introduction C.A.M. van Swaay Biodiversity and conservation The world’s biodiversity is overwhelming. The total number of species is estimated at around 8.7 million, of which only 1.2 million are already catalogued (Mora et al., 2011). Most of this biodiversity is concentrated in the tropics, but even a small country in the temperate climate zone of Western Europe, the Netherlands, still holds approximately 47800 species (Noordijk et al., 2010). And although this little part of the world is one of the best investigated in the world, every year is good for newly discovered species. A thorough investigation of a small nature reserve near Tilburg in the province of Noord Brabant revealed 50 new species for the Netherlands and one for science (Van Wielink, 2011). Nature is dynamic and species have always come and gone. As the human population grew, the impact of mankind on biodiversity has also grown. The Dutch landscape changed from forest dominated before the Roman Age to agriculture dominated from the Middle Ages onwards. This has led to a huge shift in the accompanying species, including the butterfly fauna (WallisDeVries & Van Swaay, 2009). From the 1950s onwards another large shift happened turning the semi-natural grasslands that dominated the countryside into intensively used Lolium perenne monocultures with no suitable habitat for any butterfly-species. This has led to a fear for a biodiversity crisis leading to the extinction of many species. Although there are many signs that such a crisis is well on the way (Conrad et al., 2006; Thomas et al., 2008), it is hard to measure it and even harder to halt and reverse this trend. Where a complete description of the biodiversity at a national scale is almost impossible, we can try to monitor the In a few decades Dutch grasslands changed from species-rich changes in biodiversity using indicators. semi-natural grasslands to Lolium perenne monocultures. Many indicators have been proposed, but Pereira et al. (2013) give an overview of the Essential Biodiversity Variables (EBV’s) that could form the basis of monitoring programs worldwide. One of them is ´Abundances and distributions of species populations: counts or presence surveys for groups of species´, e.g. those that are easy to monitor or of special importance for ecosystem services, over an extensive network of sites, complemented with incidental data. Butterfly Monitoring 7 Schemes provide such data making butterflies very useful indicator species for measuring changes in biodiversity (Van Swaay et al., 2008). At the Convention on Biological Diversity (CBD) meeting in Nagoya (Japan, 18 to 29 October 2010) the Strategic Plan for Biodiversity 2011–2020 was adopted. It proposed five goals and 20 so-called Aichi targets. In line with this a new EU biodiversity strategy was adopted by the European Commission in May 2011. This provided a framework for the EU to meet its own biodiversity objectives and its global commitments as a party to the CBD. One of the main targets is to halt the loss of biodiversity and the degradation of ecosystem services in the EU by 2020, and restoring them as far as feasible, while stepping up the EU contribution to averting global biodiversity loss (EEA, 2012). The strategy includes the development of a coherent framework for monitoring, assessing and reporting on progress in implementing actions. Such a framework is needed to link existing biodiversity data and knowledge systems with the strategy and to streamline EU and global monitoring, reporting and review obligations. Some indicators provide specific measurements and trends on genetic, species and ecosystem/landscape diversity, but many have a more indirect link to biodiversity. Very few were established specifically to assess biodiversity. The status indicators on species only cover birds and butterflies, since these are the only taxa/species groups for which harmonized European monitoring data are available (EEA, 2012) It is important that one of the indicator species groups represents the insects. Insects are by far the most species-rich group of animals, representing over 50% of terrestrial biodiversity (Mora et al., 2011; Noordijk et al., 2010). Contrary to most other groups of insects, butterflies are well-documented, easy to recognize and popular with the general public. Thomas (2005) shows how well four different schemes, used successfully to assess changes in British butterflies (as well as Dutch butterflies), may be representative of other taxa. The four schemes include Red Lists, mapping schemes (atlases), Butterfly Monitoring Schemes and occasional surveys. Thomas (2005) also demonstrated that extinction rates in British butterflies are similar to those in a range of other insect groups over 100 years once recording bias is accounted for, although probably lower than in aquatic or parasitic taxa. It is concluded that butterflies represent adequate indicators of change for many terrestrial insect groups, but recommended that similar schemes be extended to other popular groups, especially dragonflies, bumblebees, hoverflies and ants. Comparisons with similarly measured changes in native bird and plant species suggest that butterflies have declined more rapidly than these other groups (Thomas et al. 2004). Mountains can have a high butterfly diversity. 8 Butterfly research in the Netherlands Butterflies have been popular in the Netherlands already for a long time. In the Golden Age (17th century) people like Johannes Goedaert, Stephen Blankaart and Maria Sybilla Merian studied butterflies and their metamorphosis (Bos et al., 2006). A major step forward was the publication of the first overview of Dutch butterflies by De Graaf (1853), soon followed by more studies (e.g.