How animals shape the planet in surprising ways

Hundreds of animals, from tiny ants to mighty hippos, are shaping the Earth’s surface as powerfully as floods and storms. These animals effectively act as landscape engineers, reorganising soils and sediments. Yet their combined global impact has never been explored, until now.

Research that my colleagues and I conducted shows that animal engineers are much more diverse, widespread and globally significant than previously recognised. We estimated that the combined energy they devote to landscape-shaping processes is equivalent to the energy of hundreds of thousands of river floods.

Animals act as landscape architects as they feed, create shelter, reproduce and simply move around. Beavers build dams that form wetlands and change river channels. Spawning salmon move huge amounts of river sediments too, similar to the amounts moved by floods. Yet, beyond such charismatic and iconic examples, animal landscape engineers can be viewed as curiosities – interesting but uncommon, with healthy scepticism about their role in landscape change.

Most studies focus on a single species, so we collected evidence from hundreds of studies to understand the global significance of these animals. We focused on animals living on land or in rivers, lakes, wetlands and other inland water bodies. Oceans host important engineers too, but they were not included in our study.

My team was astounded by the diversity of landscape engineers we uncovered. The list we compiled included 500 wild animal species including insects, mammals, fish, birds, reptiles and crustaceans. More than a quarter of those 500 species are threatened or vulnerable in some way. This means their landscape-shaping effects – mixing, eroding or stabilising soils and sediments, building landforms – could disappear before they are fully understood.

Animal architects include some of the smallest creatures on Earth, such as ants, termites and aquatic insect larvae, as well as the largest, such as elephants, hippos and bison. As a group, they are globally widespread across land and in water, in all major ecosystem types. We showed that despite covering only 2.4% of the planet’s land surface, freshwater habitats host over a third of these fascinating animals.

We searched thousands of published articles for mentions of animal engineers to compile a comprehensive list of species. We explored their global distributions using free online biodiversity data. We used recent estimates of the total biomass of ants, mammals and all living things to estimate the combined biomass of animal engineers. Then, we converted this information to calorie content and estimated how much of that energy is used to shape landforms and landscapes.

We inevitably missed some studied species in our searches. For instance, we know that the tropics and subtropics are biodiversity hotspots, but fewer animal agents of landscape change were reported there. This is because research and resources have been concentrated in places like Europe, the US and Australia. Countless more species remain unreported or even undiscovered, especially smaller, less visible animals such as insects.

Another consideration is that our energy estimates for livestock substantially exceeded wild animals due to their large body size and high abundance. Yet how livestock shapes the landscape depends on how the animals are farmed. Intensive farming of large livestock breeds can increase soil erosion and flood risk, while low-density regenerative farming can improve soil health.

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Rewilding potential

Nature loss is intrinsically linked with the climate crisis. Natural habitats such as forests and wetlands capture and store carbon dioxide, helping to mitigate climate change. They also help us to adapt to the impacts of climate change, by altering how quickly water moves through landscapes for example, which reduces the severity of floods and droughts.

In rewilding projects around the world, free-roaming pigs, deer, ponies and cattle introduced as landscape engineers increase carbon storage by changing vegetation and soils and helping reduce flood risk downstream. Beavers create “emerald refuges” in wildfire-scorched landscapes by damming streams to create ponds and wetlands. Hippo trails lead to the creation of new river channels that direct water flow to different areas.

Finding ways to harness the enormous energy potential of landscape-shaping animals could help simultaneously mitigate and adapt to climate change and boost biodiversity.

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