Spatial shifts in steppe bird hotspots over two decades: Assessing conservation priorities and the role of protected areas☆

The analysis of biodiversity hotspots is crucial for defining and prioritizing conservation areas and efforts. However, periodic reassessments are needed to track spatial shifts and changes in species composition over time. Focusing on steppe birds, one of the most threatened groups of birds in Europe, we identified historical (1998-2002) and current (2014-2023) hotspots (high value areas for conservation, defined as species-rich areas with higher frequency of rare and threatened species) and spatial shifts between the two periods in Spain, their main European stronghold. We also evaluated i) whether hotspots were covered by Protected Areas (PAs), ii) the effectiveness of PAs at maintaining species-rich steppe bird communities; and iii) which species should be considered as conservation priorities. We evidenced spatial changes of hotspots during the last two decades. Two regions in Central and NE Spain collectively accounted for >50 % of historical and current hotspot areas, while other regions in NW Spain lost >50 % of hotspot areas. The extent of hotspots including PAs increased from 21.8 % to 29.4 %, however, overall species richness declined over the two periods, particularly outside PAs. This indicates that PAs can be an effective conservation tool for steppe bird communities. Finally, we identified nine "high priority" species for conservation that included two sandgrouse, two bustards, two passerines, one raptor, one wader and one gamebird. Our results shed light on how quickly the conservation status of species and communities can change, the importance of continuous monitoring, and the urgent need for adaptive conservation strategies to protect biodiversity.