Examining the relationship between local extinction risk and position in range

Over half of globally threatened animal species have experienced rapid geographic range loss. Identifying the parts of species’ distributions most vulnerable to extinction would benefit conservation planning. However, previous studies give little consensus on whether ranges decline to the core or edge. Here we build on previous work by using empirical data to examine the position of recent local extinctions within species’ geographic ranges, addressing range position as a continuum and exploring the influence of environmental factors. We aggregated point locality data for 125 species of galliform birds across the Palearctic and Indo-Malaya into equal area half degree grid cells and used a multi-species dynamic Bayesian occupancy model to estimate the rates of local extinctions. Our model provides a novel approach to identify loss of populations from within species ranges. We investigated the relationship between extinction rates and distance from range edge, examining whether patterns were consistent across biogeographic realm and different categories of land-use. In the Palearctic, local extinctions occurred closer to the range edge in both unconverted and human-dominated landscapes. In Indo-Malaya, no pattern was found for unconverted landscapes but in human dominated landscapes extinctions tended to occur closer to the core than the edge. Our results suggest that local and regional factors over-ride any general spatial patterns of recent local extinction within species’ ranges and highlight the difficulty of predicting the parts of a species’ distribution most vulnerable to threat.