Britain’s prolonged spell of extreme heat and drought is beginning to reshape the country’s wildlife, with scientists warning that some of the most serious consequences may not become visible until next year. While wildfires have attracted much of the attention during the unusually hot summer, the effects of water shortages are also being felt across grasslands, trees, wetlands, rivers and the animals that depend on them.
Across parts of Britain, normally green landscapes have turned brown as lawns dry out, trees lose their leaves and ponds, ditches and bogs shrink. Although some of these changes may appear temporary and could reverse after substantial rainfall, wildlife can suffer longer-lasting consequences because many species depend on specific habitats and food sources that are being disrupted by the drought.
Britain’s wildlife is particularly vulnerable because many native species have evolved in a relatively cool and wet climate. Unlike species in naturally dry regions, British plants and animals have historically faced less evolutionary pressure to develop strong adaptations to prolonged heat and water scarcity. As a result, extreme weather can place considerable stress on species that are accustomed to regular rainfall and cooler temperatures.
Some plants, however, are capable of surviving short periods of drought. Grass may stop growing and turn straw-coloured during prolonged sunshine, but its roots can remain alive and begin producing fresh growth once rain returns. Mosses and liverworts are also capable of entering a dormant state when they dry out. Sphagnum mosses, which are particularly important in upland bogs because they help retain water, can recover if dry conditions do not persist for too long.
The greater concern is for animals that rely on these wet environments. Numerous insects and other invertebrates use bogs, ditches and other damp habitats to complete important stages of their life cycles. Even a temporary disappearance of water can therefore affect their survival and reproduction. Trees are also under significant pressure because they require a continuous supply of water. Mature oak trees, for example, can consume hundreds of litres of water a day. When their roots cannot obtain enough moisture, leaves can die and branches may be lost, helping explain the widespread browning and premature leaf loss observed this summer.
Aquatic species face another serious challenge as water temperatures rise. Fish and aquatic invertebrates depend on oxygen dissolved in water, but warmer water is capable of holding less oxygen than colder water. Low oxygen levels can therefore leave aquatic animals severely stressed, particularly during the hottest periods. Reduced water levels can compound the problem by concentrating animals into smaller areas where oxygen may become increasingly scarce.
Birds and mammals are also being forced to cope with greater water demands during periods of intense heat. Many animals regulate their body temperature through evaporation. Mammals may pant or sweat, while birds use panting and other mechanisms to release heat. Heat-stressed birds have consequently been observed seeking shade and keeping their wings slightly open as they attempt to cool themselves.
The drought could also have consequences that travel through the food chain. Warm and dry weather can encourage some flying insects, but an increase in adult butterflies, for example, does not necessarily indicate that butterfly populations are thriving. Many butterfly species depend on particular plants during their larval stage. If those host plants are weakened or destroyed by drought, caterpillars may struggle to find sufficient food.
The northern brown argus butterfly provides one example. The species lays its eggs on common rock rose, a plant found in parts of northern England. If the plants deteriorate before the caterpillars emerge, the young insects can face a severe shortage of food. The immediate impact may be difficult to detect, but fewer surviving caterpillars could eventually mean fewer adult butterflies appearing the following year.
Such disruptions could extend beyond individual species. A decline in caterpillars and butterflies would reduce an important food source for animals higher up the food chain, including songbirds, spiders and frogs. Specialist species that depend closely on particular plants or habitats may be especially vulnerable, raising concerns about declining populations if extreme droughts become more frequent or prolonged.
Experts say people can nevertheless take simple steps to support wildlife during periods of extreme heat. Providing shallow containers of water can give birds access to drinking and bathing facilities, while allowing some garden plants commonly considered weeds, such as cat’s ear, to remain can provide nectar and pollen for insects. Leaving portions of lawns uncut and allowing vegetation to grow taller can also create shaded, cooler areas that offer refuge to wildlife during the hottest conditions.
The current drought therefore represents more than a temporary change in the appearance of Britain’s countryside. While some plants may recover quickly when rainfall returns, the effects on insects, birds, amphibians and other wildlife could emerge much later. In some cases, the true ecological impact of this summer’s extreme weather may only become clear during the next breeding season, when changes in food availability and reproduction begin to translate into visible population declines.
