Deserts rarely conjure up images of flourishing life. They are, however, home to several species of birds that, because of their habitat, provide researchers with a unique opportunity to study the links between survival, breeding success and temperature. Researchers are learning about the effects of climate change from these desert birds and their findings are very concerning.

While the desert is a challenging environment at the best of times, the increasing number of heat waves in these regions is placing huge pressure on endemic bird populations. Increased temperatures present birds with significant physiological challenges, making it more difficult to balance their intake and consumption of energy and water. Rising temperatures also put strain on breeding processes. Prof Andrew McKechnie, of the Department of Zoology and Entomology in the Faculty of Natural and Agricultural Sciences at the University of Pretoria (UP), is a physiologist who is studying the potential of desert birds to predict the effects of climate change.

Prof McKechnie and his postgraduate students work in close collaboration with Dr Susie Cunningham from the University of Cape Town’s Percy FitzPatrick Institute of African Ornithology. The Hot Birds Programme, as it is suitably named, conducts research primarily in the Kalahari Desert, which covers an area of 900 000 square kilometres in Botswana, Namibia and South Africa. The programme includes a number of research areas, such as the ability of different desert birds to handle increasing maximum temperatures and more frequent heat waves. Deserts around the globe are showing an increase in the number of hot days they experience per year – in parts of Australia, for instance, the number of days per year with temperatures exceeding 40˚C has doubled since the 1960s. Also in Australia, incidents of hundreds to thousands of birds dropping dead on a single day during an extreme heat wave are becoming more frequent.

McKechnie’s research over the past few years has studied desert birds in North America, Australia and the Kalahari, using a standardised approach to quantify the heat tolerance limits of birds. Placing birds in metabolic chambers in order to measure their physiological capacity to keep cool may sound drastic, but this is precisely the type of data that is essential in order to understand if, and to what extent, birds are able to handle such extreme heat waves.

Evaluating the temperature-dependency of physiological and behavioural responses in wild birds enables McKechnie to better predict how and when birds might experience dehydration or heat stress during extremely hot weather events. McKechnie is using the white-browed sparrow-weaver as a model species to better understand the differences in sensitivity among populations when it comes to extreme heat conditions. ‘This kind of data,’ McKechnie says, ‘enables you to come up with fairly convincing predictions of what climate change means.’

McKechnie will soon be able to take this valuable research further with the opening of a state-of-the-art temperature-controlled facility at UP’s experimental farm. The University has invested millions of rands into the commissioning of this facility in the interest of furthering research around climate change.

As many of the devastating effects of climate change will only be realised in the decades to come, the international research community still has many questions which this facility will provide the capacity to answer. McKechnie says the facility will be able to simulate heat waves and allow researchers to test the ability of birds to acclimatise to different thermal conditions. One of its projects will involve breeding birds in captivity at different temperatures, in order to determine the effects of temperature on reproduction and other important processes. While the burning question of whether birds can adapt to temperatures higher than those they currently experience, remains unanswered, McKechnie is hopeful that with this new facility, he will be able to find the answer.

In conclusion, Prof McKechnie emphasised the importance of this research area: ‘Birds are much more important than people realise. The ecosystem services they provide, from pollination to pest control, are significant. When we lose birds in these ecosystems, we are going to have a lot of problems.’

Homepage Banner: The white-browed sparrow-weaver, a widepspread southern African bird species that has become the focal species for research into the effects of rising temperatures on arid-zone birds (Photo: Adam Riley)