Coping with the heat (Focus - August)

I really struggle during heatwaves. At home, I do all I can to keep the house cool and to make sure there is some shade into which we can retreat at the hottest time of the day. But, how is wildlife, which has evolved over long time periods to be adapted to our normal climate, impacted by the increasingly frequent hot and dry spells? Well, in numerous direct and indirect ways.

We will see in our gardens how fruit and veg may mature too quickly and drop fruit prematurely. In the field, this can mean that crops of berries, nuts, and fruits that birds and animals normally rely on in autumn, may be gone by the time they need them. Although we can water our wilting garden plants and seedlings, in the wild they may perish, and a new generation will be lost. If the plants provide food for the larvae of insects like butterflies and moths become desiccated and die, the larvae won’t be able to grow sufficiently to progress to their overwintering stage, diminishing the numbers that emerge next year.

Anyone trying to dig into their flowerbeds will know how rock-hard the soil can get. Well, imagine if you rely on muddy soil with which to build a nest, or on digging into that soil to get food – as badgers, hedgehogs and many birds do. Life becomes very difficult for them. And things are just as bad for the creatures in that hardened soil, making it an inhospitable place. The worms and invertebrates that moles feed on are harder to find, so they must dig deeper to find moist soil and food.

While every creature needs to drink water in some way, amphibians such as frogs and toads rely on being able to keep moist, but as cool damp areas become increasingly rare, they risk death from dehydration. During heatwaves, water temperatures in ponds and rivers rise, resulting in reduced dissolved-oxygen levels, which in turn can kill fish. At the same time, the warmth encourages algal blooms, which can smother other wildlife and become toxic. If ponds dry out completely before tadpoles have competed their transition to froglets or toadlets, they will die.

Added to all these problems is the increasing risk of wildfires, or, even worse, deliberately started fires. This is a particular problem on our southern heathlands, many of which are close to built up areas, which seems to increase their vulnerability.

Obviously, it is not all bad news. Some species undoubtedly benefit from the heat and drought. But cumulatively, repeated heatwaves will favour the more resilient species, which can adapt in the short term or can move to more favourable locations and are able to recolonise later. Sedentary species, or those whose population take many generations to rebuild, may become locally extinct, eventually leading to a reduced flora and fauna of robust, adaptable species. Unfortunately, many of these are what we currently think of as pests. In future, our flora and fauna may be less diverse, less interesting, and significantly different to what we are comfortable with.

Andrew Graham