Endemic birds of the Fynbos biome: a conservation assessment and impacts of climate change

Abstract

SummaryThe South African Fynbos biome, a global biodiversity hotspot with high endemism and species richness, has six endemic bird species. These are important not only intrinsically, but also for ecological functioning and as flagships for South Africa’s economically valuable avitourism sector. Little is known about population sizes or realised distribution ranges of these six species, but projected range modelling based on occurrence from the South African Bird Atlas Project (SABAP) has suggested these species are vulnerable to climate change. We estimate global population sizes for these six endemics based on densities calculated from two intensive biome-wide point count surveys in 2012. We modelled regions of suitable climatic space, from which we established that mean annual temperature and the temperature of the warmest quarter of the year appear to limit Cape Rock-jumperChaetops frenatusand Protea CanarySerinus leucopterusranges. Both species have seen an apparent > 30% decrease in range and reporting rates (a proxy for abundance) in the twenty years between SABAP atlas periods (1987–1991 and 2007–ongoing). The Cape Rock-jumper result is unexpected: encounter rates are higher in shorter vegetation, dry slopes and habitats with more recent occurrence of fire – all proxies for proximate causes of climate change on the Fynbos. Although coastal plains are highly transformed, mountain Fynbos is the best protected of all the world’s Mediterranean-climate habitats, with relatively little anthropogenic land transformation. Long term weather datasets from the Fynbos demonstrate significant warming since 1960. We conclude from these lines of evidence that these decreases are consistent with the loss of suitable climate space and inability of these species to adjust physiologically to increasing temperatures.