Climate change and birds: perspectives and prospects from southern Africa
AbstractGlobal climate warming, now conclusively linked to anthropogenically-increased CO2 levels in the earth\'s atmosphere, has already had impacts on the earth\'s biodiversity and is predicted to threaten more than 1 million species with extinction by 2050. Climate change in southern Africa is expected to involve higher temperatures and lower rainfall, with less predictability and a greater frequency of severe storms, fires and El Niño events. The predicted changes to birds in Africa — the continent most at risk from climate change — have hardly been explored, yet birds and many other vertebrates face uncertain futures. Here, in one of the first focused analyses of the correlates of climate change vulnerability in southern African birds, we offer a wide-ranging perspective on which species may be most at risk, and explore which traits may influence the adaptability or extinction risk of bird species.
Our review suggests that small nomadic species with short generation times may be least at risk. While larger-bodied species may be physiologically buffered against environmental change, their longer generation times may make them less able to adapt evolutionarily to climate change. Migrant species, and those with specialised feeding niches such as pollinators, are also predicted to be at risk of population declines, based on low ability to adapt to new environments when introduced there as aliens. Species with small ranges (<50 000km2) restricted to the two southern African biodiversity hotspots most at risk from climate change — the Cape Floral Kingdom and the Succulent Karoo — are ranked according to low, medium or high risk of extinction. Those restricted to mountain slopes, mountain tops or islands, and those occurring mainly at the southern or western extremes of these biomes, are ranked as highest risk. These include endemic sunbirds, warblers and rockjumpers — none of which are currently recognised Red Data species. Using climate envelopes we modelled the possible range shifts by 2050 of three pairs of species found in habitats considered to be at risk: fynbos, mountain and arid Karoo. All six species lost substantial portions of their range (x# = 40%), with the montane Drakensberg Rock-jumper Chaetops aurantius losing most (69%). Significant reductions of available climate space in all species may interact with life history characteristics to threaten many southern African bird species unable to shift geographic range or adapt to novel resource conditions. We conclude with a list of research priorities and testable hypotheses which may advance our understanding of the complex influence that climate change is likely to have on African, particularly southern African, birds.
Ostrich 2004, 75(4): 295–308