Africa’s bats could survive climate change – if they can find somewhere to live

Climate change and changes in the way land is used are the two biggest threats to wildlife because they change the environment in which animals survive and thrive. Knowing how species respond to these pressures is central to planning conservation actions.

A number of studies have modelled how climate change will affect vertebrate distributions. But little is known about bats from tropical and subtropical regions, especially in Africa.

Bats are particularly sensitive to changes to their environment because of their slow reproductive rates, dependence on stable roosts, and sensitivity to climatic extremes that shape insect availability – their main source of food.

They therefore need both suitable foraging landscapes and the availability of caves for roosting. Research has been done on how bats will be affected by the effects of climate change such as rising temperatures. What has been overlooked is the fact that cave-dependent bats can’t survive in climatically suitable areas without access to suitable roosts.

So even if a future landscape has the right temperature and rainfall, it may be of little use to a bat if there is nowhere suitable to roost. That led us to a simple question: what happens when the places with the right climate aren’t the places with caves?

Having studied bats since 2017, I have spent much of my research career investigating their ecology and dependence on particular habitats. This experience led me to question where climate change might push wildlife. I wanted to understand whether Africa’s cave-dwelling bats would actually be able to find somewhere to live as the climate changes.

My co-author Mark Keith and I set out to answer this by building a model that brought together future climate conditions and the availability of caves and rocky roosting habitat across sub-Saharan Africa. We used cave-dwelling long-fingered bats called Miniopteridae as our study group to explore how these two essential pieces of the puzzle might overlap in the future.

Long-fingered bats are found widely across Africa and depend heavily on caves for shelter. They also commonly occur alongside other cave-dwelling bat species, making them a useful group for understanding how climate change could affect bats that rely on caves.

Our findings suggest that Africa’s cave-dwelling bats face a double challenge. Climate change could shrink the areas where they can live, but even where future conditions remain suitable, there might not be caves.

Places need to found where three things come together: the climate remains suitable; there is somewhere for the bats to live; and they can move between the places they need.

These could become critical safe havens for bats as the climate changes.

Modelling where bats can survive

We used an existing database of 551 reliable records showing where these bats have been found across sub-Saharan Africa. We then used these records to ask where conditions could remain suitable for them as the climate changes. Using a computer model, we matched each of these places with its local climate, such as how hot, cold or wet it gets, to work out what conditions the bats need. We then asked the model where those conditions would still exist around 2070, if the world carries on warming at a moderate rate.

We found that, depending on how the climate changes in the coming decades, the area with suitable conditions for these bats could shrink by 36% to 64% by 2061-2080. The areas that remained suitable were concentrated mainly in southern Africa, the eastern highlands and Madagascar.

We then went on to answer the next question. Were there caves in those places?

When we compared the areas with a suitable future climate with the locations of suitable caves and rocky landscapes, the picture became much more worrying. Only around 5% of the areas with suitable caves also had a climate expected to remain suitable for the bats. And when we considered how vulnerable the surrounding landscape was to future change, that fell to around 2%.

In other words, the places where bats might find the right climate and the places where they might find a home barely overlapped.

Read more:
South Africa’s cave-dwelling bats need more protection – to keep people safe too

In addition, for some cave-dwelling bats, survival is not simply about finding one suitable cave. They may depend on a network of caves spread across the landscape, moving between them at different times of the year. That means the landscape between caves matters too.

A cave might provide an ideal shelter, but if the surrounding landscape has become heavily fragmented by roads, cities, agriculture or other changes, reaching another suitable cave may become much more difficult. And flying takes energy. If bats have to travel further between places where they can feed, rest and reproduce, they may have to spend more of their limited energy simply getting around. For animals already dealing with a changing climate, that could add another layer of pressure.

Read more:
Fruit bats: the winged ‘conservationists’ reforesting parts of Africa

A problem that goes beyond bats

Our findings are important for a range of animals. A frog may need a particular wetland. A bird may depend on a particular type of forest. A plant may only grow in a certain kind of soil. As the climate changes, the conditions these species need may shift, but their homes may not.

This creates a challenge for conservation: it is not enough to ask where the climate will be suitable for wildlife in the future. We also need to ask whether wildlife will actually have somewhere to live when it gets there.