Livestock grazing displaces spiders and promotes ticks.

In many parts of the world, traditional landscapes once dominated by wild herbivores are undergoing dramatic changes. Grazing by livestock has displaced native herbivores, leading to shifts in soil composition, plant diversity, and the delicate balance of predator-prey interactions.

Editorial Team Wild beim Wild — February 22, 2025

These changes are often subtle and develop over years, but their consequences can be far-reaching.

A long-term study in the Spiti Valley in the Himalayas provides information on how these changes affect soil-dwelling arthropods, including spiders, ticks and mites.

The results reveal a worrying trend: Spider populations are declining, while disease-carrying organisms such as ticks and mites are thriving.

These changes have direct impacts on biodiversity, ecological stability, and even human health. Learn more about biodiversity .

Global livestock grazing: the basics

The expansion of pastureland for livestock has been changing landscapes worldwide for decades. As global demand for meat and dairy products increases, ranchers and agricultural companies are clearing more land for cattle, sheep, and other grazing animals.

In places like the Amazon rainforest, vast areas of forest are being cleared to create pastureland, contributing to deforestation and habitat loss.

Grasslands, savannas and even arid regions are also being converted into pastureland, often at the expense of native ecosystems.

In some regions, a switch is being made to regenerative grazing techniques, in which the animals are kept alternately on different pastures to imitate natural grazing patterns and allow the soil to recover.

Others are researching plant-based alternatives and lab-grown meat to reduce pressure on the planet. Plant-based diets are also gaining in importance.

The challenge lies in finding a balance between food production and environmental sustainability, and as global appetite grows, the search for solutions becomes ever more urgent.

Although livestock farming plays a detrimental role in feeding the world, its rapid expansion raises a multitude of enormous problems.

Spiders in livestock-farming areas

The researchers found that areas with livestock farming have fewer spiders but more grasshoppers, ticks, and mites. Spiders play a crucial role in maintaining ecological balance by controlling insect populations.

The study's co-author, Sumanta Bagchi, is an associate professor at the Centre for Ecological Sciences (CES), Indian Institute of Science (IISc).

“Spiders are predators; their ecological role is comparable to that of wolves, lions, and tigers. A low spider population can free grasshoppers from predator control and lead to many downstream changes in an ecosystem. Taken together, these effects alter the flow of materials and energy,” explains Bagchi.

Replacement of wild herbivores with livestock

Bagchi and his team have been studying the impact of livestock farming on the Spiti Valley ecosystems for over 15 years. They have found that wild herbivores like yaks and ibex once thrived worldwide, but are now restricted to protected areas. Elsewhere, domesticated animals dominate.

For the study, the researchers tracked over 25,000 arthropods from 88 taxa, including spiders, ticks, mites, bees, wasps and grasshoppers.

They monitored fenced plots grazed by either wild or domestic animals and analyzed soil moisture, pH levels, and vegetation biomass.

Disturbance of arthropod habitats

Shamik Roy, a former PhD student at CES and co-author of the study, pointed out that arthropods have long been associated with native livestock farmers.

“The biotic and abiotic variables of vegetation and soil are intertwined in complex ways that we still cannot decipher. Arthropods depend heavily on them to find food and habitat, a connection that has developed over centuries with the native grazers in the ecosystem,” Roy said.

When these grazers are replaced, disturbances occur in arthropod populations. The study found that spiders declined in areas where livestock grazed, while ticks and mites flourished.

The reasons for the decline in spider populations are unclear, but the reduced availability of prey and changes in vegetation could contribute.

Increasing disease-carrying arthropods

Pronoy Baidya, a former PhD student at CES and co-author of the study, points to a worrying trend.

“One of the most surprising observations was the massive difference in the frequency of ticks and mites between native grazing animals and farm animals,” said Baidya.

Eighty percent of cattle worldwide carry ticks, posing a danger to both the animals and humans. "This is a major problem for zoonotic diseases and One Health," said Baidya.

Grazing of animals and vegetation

Grazing by livestock has complex effects on vegetation structure and soil health. The study found that areas with grazing livestock have a different plant composition than areas with native herbivores.

Changes in plant species affect arthropod diversity and alter food availability for different species.

Soil conditions, including moisture and pH, also change due to grazing by livestock. These changes affect microbial communities and further influence the ecosystem.

Healthy soil supports diverse vegetation, which in turn maintains a balanced ecosystem.

Nature conservation and land management

To mitigate these impacts, researchers suggest reintroducing native herbivores and monitoring vector-borne diseases. Conservation policy should focus on balanced livestock grazing and ecosystem preservation. Learn more about environmental and nature conservation .

“Currently, most common lands are poorly managed, so that people from the villages cannot sustainably use these common lands for their livelihoods and deprive the local herbivores of their grazing land,” said Baidya.

"Our study will hopefully serve as an example that prompts governments to take serious steps to first release the commons and then begin proper ecological restoration of these areas."

The reintroduction of wild herbivores and the management of pastureland could help restore ecosystems and reduce disease risks.

These changes necessitate measures to protect biodiversity and maintain ecological balance. Sustainable land-use practices and improved management of pastureland can prevent further ecological disturbance.

The study was published in the journal Ecological Applications .

Further reading