Climate change is having profound impacts on biological systems. Desert birds are particularly vulnerable to rising temperatures, since many species inhabit areas characterized by extremely hot weather in summer and water resources that are scarce and highly unpredictable. Climate change models predict that nearly all the world’s hot deserts at subtropical latitudes will become significantly hotter during the 21st Century, with maximum air temperatures expected to increase by 3 to 5°C by the 2080s (IPCC 2007). The accompanying increase in the frequency and intensity of extreme heat waves (Meehl and Tebaldi 2004; IPCC 2007), leading to above-average temperatures that exceed the upper limits of organisms’ thermal tolerance, is potentially one of the greatest direct short-term threats to biodiversity (Wolf 2000). In extreme instances, heat waves can lead to catastrophic mortality events (Welbergen et al. 2007), such as those recently observed in the deserts of Western Australia, which resulted in thousands of parrots and finches dying of heat stress and dehydration within two weeks (Towie 2009). We can confidently predict that increasing temperatures in hot deserts globally will cause range changes of birds, but at present we have limited capacity to predict which species will respond first or when the response will occur. Making such predictions requires a mechanistic understanding of the link between the physical/environmental characteristics of habitats and organismal performance. Building such an understanding is the core goal of the Hot Birds programme, which has study sites in the Kalahari, the Sonoran Desert in southwestern USA, and the hot deserts of Australia.
We are currently working towards this goal using several complementary approaches which model the impacts of increased temperatures on the behaviour and physiology of desert birds. These approaches involve comparative studies across desert bird communities assessing behavioural and physiological changes in response to heat stress, and focal species studies aimed at understanding fitness consequences of these changes in detail. Core studies fall under the following themes:
- Heat stress in free-ranging birds: integrating physiology and behaviour
- Evaporative cooling and heat tolerance
- High temperatures and their impacts on fitness
- Thermal landscapes and their potential to buffer the effects of temperature extremes
Further information on each research theme, and on the ‘Hot Birds’ team, can be found on the ‘Hot Birds’ web site.