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Ant mounds play a critical role in sustaining biodiversity

Ants, often considered a nuisance in our gardens, may be significantly more important for biodiversity than previously thought, according to a recent study conducted by Rikke Reisner Hansen and colleagues from the Department of Ecoscience at Aarhus University. The researchers studied ant mounds on Danish heathlands to understand their impact on other insects and plants.

“The ants drag dead animals back to the ant mound, and this adds carbon and other important nutrients to the surrounding soil,” explained Hansen. “The ant mound moreover warms up the surrounding ground, and in springtime, adders, lizards and beetles like to rest near ant mounds for warmth. The heat and the nutrients create unique conditions that allow certain plant species that don’t otherwise thrive on heathland to thrive on the ant mound.”

To investigate the role of ant mounds in heathland wildlife, Hansen went to the heath and looked for two types of ant mounds: those belonging to the narrow-headed ant and those belonging to the yellow meadow ant. She dug deep holes next to the ant mounds, enabling her to study how the mounds affected the soil, roots, and wildlife both above and below the mound. She also measured the temperature on top of the ant mound and examined the soil around and underneath it to determine the soil nutrients.

Hansen found that the top part of the ant mound acts like a “miniature Costa del Sol for insects and reptiles. The animals exploit the excess heat from the ants for warmth in early spring and on chilly mornings.” She added that plants growing on an ant mound would blossom or come into leaf faster than the same species growing in the surrounding heathland soil. This is a significant advantage for insects that feed on pollen and nectar, as the ant mounds introduce an extra flowering season.

The Alcon blue butterfly, which lives only on heathland where ants are present, has developed a method to trick ants into believing its caterpillar is the ant queen. 

“The Alcon blue lays its eggs on the rare marsh gentian plant,” said Hansen. “The caterpillar feeds on marsh gentian seeds during the first three stages of its life. When it has grown big enough, it falls to the ground and begins to emit a smell and a sound identical to those of a queen ant larva.” Worker ants then drag the caterpillar into the nest, sometimes neglecting their own offspring, which can lead to the colony’s demise.

Denmark is home to 12 species of gossamer-winged butterflies, with 11 of these species thriving best in places where ants also live. A handful of these species depend on ants to complete their life cycle. Protecting ant mounds can thus be a crucial step in mitigating the biodiversity crisis.

The world, including Denmark, is experiencing a biodiversity crisis, with the loss of species accelerating as important habitats are destroyed through deforestation, heathland cultivation, and bog drainage. In Denmark alone, 1,844 species of animals, plants, and fungi are under threat of extinction. The Alcon blue butterfly, for example, has lost more than 15 percent of its habitat in Denmark within the past 40 years.

Hansen suggests that the way we manage our heathlands could be contributing to this decline. “We tend to manage our heathlands as a homogenous landscape. We often apply the same management method throughout a heathland to preserve it as an open landscape. For example, we allow too many animals to graze the land. Or we use large machines to cut the vegetation. Unfortunately, this destroys the ant mounds.”

“To ensure many different plants and animals on the heath, we need to rewild the landscape, or at least return it to the way it was before machinery took over from traditional management systems,”

More about the biodiversity crisis

The biodiversity crisis, often referred to as the sixth mass extinction, represents a rapid loss of biodiversity on Earth. Biodiversity, which is the variety of life in a particular habitat or ecosystem, is crucial for the stability of ecosystems and the services they provide, including food production, clean water, and carbon sequestration.

Unfortunately, species are disappearing at an alarming rate, much higher than the natural background rate of extinction. It’s estimated that dozens of species are going extinct every day. This loss of biodiversity is largely driven by human activities.

Key factors contributing to the biodiversity crisis include:

Habitat Loss and Degradation

Human activities such as deforestation, urbanization, and industrial agriculture lead to destruction of natural habitats, which is the primary cause of the current biodiversity crisis. When habitats are destroyed, the species that live there are often pushed to extinction.

Climate Change

Changes in temperature and precipitation patterns, as well as increased frequency and intensity of extreme weather events, can disrupt ecosystems and make it difficult for many species to survive.


This refers to the unsustainable use of species for resources, such as overfishing or hunting a species to the point where its survival is threatened.


Various forms of pollution, including air, water, and soil pollution, can have devastating effects on biodiversity. For example, pesticides can harm non-target species, and plastic waste can injure or kill marine animals.

Invasive Species

These are non-native species that are introduced to new environments, often by human activities, where they outcompete native species for resources and can cause them to go extinct.

The biodiversity crisis is not just an environmental issue but also a developmental, economic, security, social and moral issue as well. The loss of biodiversity threatens our food supplies, opportunities for recreation and tourism, and sources of wood, medicines and energy. It also interferes with essential ecological functions.

Addressing the biodiversity crisis requires global cooperation. This includes measures to protect and restore habitats, combat climate change, transition to sustainable agricultural practices, and regulate hunting and fishing. Additionally, it involves concerted efforts in scientific research, education, and policy-making to create sustainable solutions for biodiversity conservation.


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