Determining high value areas for steppe birds in Spain: hot spots, complementarity and the efficiency of protected areas

Abstract

We have examined the distribution of 26 species of steppe birds in the Iberian Peninsula and the Balearic Islands within a grid of 5,070 10 × 10 km grid cells. The most valuable areas for steppe birds have been identified by selecting the upper 5% of the 10 × 10 km grid cells after a simple ranking based on the following criteria: species-richness, richness of rare species, rarity index, species vulnerability at Spanish, European and Global levels, and using an index combining the previous criteria. We have also used a heuristic algorithm to select those areas which offered most complementarity. The results have been analysed on a national scale and have been compared with those obtained by species assessments in previous status summaries. Finally, we have performed an analysis of the coverage afforded to locations which are valuable for steppe species by Natural Protected Areas (NPAs) and Special Protected Areas (SPAs), and an evaluation of the potential effects of temporal changes in species’ threat-status.

The combined index was the most reliable criterion for defining hotspots, encompassing 15% of the species’ distributions within 5% of the total area considered. This index showed a high level of geographical concordance with the other criteria (nearly 70% of the selected grid cells coincided). Analysis of complementarity delivered poorer results than simple rank-scoring. The analysis of the efficiency of NPA network showed a very low coverage (less than 2%) of the hotspots selected according to the Combined Index. Coverage of the SPA network was higher (nearly 45%), although it diminished (to <35%) when only steppe-defined SPAs were included. The geographical concordance between high-value areas selected using current status summaries and those chosen using earlier ones was low for European threat status (53.4%), intermediate (63.2%) for Spanish threat status and high for SPEC status (78.1%). The Combined Index showed a high level of geographical concordance between the old and new data (76.6%). We conclude that automatic scoring methods (identifying hotspots) are useful for selecting valuable areas and for analysing the efficiency of the network of protected natural spaces, as well as for examining the potential effects of status changes on hotspot definition. Furthermore, the Spanish SPA network does not cover the most important areas for steppe birds adequately.