Eradication of small burrowing mammals causes more harm than good

According to a recent study published in the Journal of Animal Ecology, current measures to protect grasslands in the Qinghai-Tibetan Plateau – which were introduced in 2000 and focus on the eradication of small burrowing mammals, such as the plateau pika and the zokor – are in fact damaging the local ecosystem and should be stopped. 

The experts argue that, since both the pika and the zokor are keystone species and major ecosystem engineers, their extermination can negatively impact ecosystem health and productivity and should be replaced with a nature-based control strategy.

“The government agency’s policy of conducting large-scale animal culling campaigns each year is not a good approach,” said study co-author Johannes Knops, an expert in Community Ecology and Trophic Interactions at Xi’an Jiaotong-Liverpool University (XJTLU).

“Our research shows that using natural predators and other ecological factors to regulate burrowing mammal populations can be a more sustainable and effective approach to grassland management.”

The Qinghai-Tibetan Plateau grasslands play a major role in the quality of water flowing into major Asian rivers such as the Yangtze, Lancang-Mekong, Yellow, Indus, and Ganges. Since rodents often cause damage to grasslands by consuming foliage, compete with grazing livestock for food, and cause soil erosion, scientists started implementing an eradication policy in 2000 – part of the Returning Grazing Land to Grassland project – in an effort to prevent grassland degradation. 

However, as the authors of the current study argue, small burrowing mammals can increase plant diversity as they increase seed dispersion and light availability by consuming taller grasses. Moreover, their burrows offer valuable refuges and habitats for other species and can contribute to the decrease of surface water runoff and soil erosion. 

“If we look at the grasslands, we will find numerous plant species, and not all animals eat the same plants, so it is crucial to consider the entire food chain rather than killing all the small mammals,” Knops explained.

The scientists also criticize the current high-cost and labor-intensive poisoning method used to eradicate these mammals, arguing that it can have unintended consequences, such as the development of resistance to poisons by target species and the possible harm it may cause to non-target species.

Finally, the extermination policy can increase human-wildlife conflict by reducing predator populations and creating imbalances in the ecosystem.

“It’s important to consider the knock-on effects of reducing the small burrowing mammal population. If there are fewer small mammals, there is less food for their natural predators, such as red foxes, steppe polecats, upland buzzards, brown bears, and mountain weasels. Not only will these larger mammals start to look for alternative food sources and increasingly prey on livestock, causing more human-wildlife conflict, but their populations will also decrease,” Knops explained.

“The eradication policy, therefore, causes the opposite effect to the one intended, as when the number of the pika and zokor’s natural predators is reduced, burrowing mammal populations can increase rapidly. This then requires more human control, which is costly and negatively impacts non-target species and the environment.”

Although the goal to control burrowing mammal populations should not be completely eradicated, it could be replaced with a nature-based control strategy which uses natural predators and other environmental factors, such as the rodents’ preferred plant species and the height of vegetation. 

Thus, some efficient methods could include providing nesting spaces for raptors, and reducing the over-grazing of livestock on the grasslands, which will allow the grass to grow taller and keep the small mammal populations at a manageable level, as they prefer to feed on shorter vegetation. 

While further research is needed to refine this approach and test its effectiveness in different grassland ecosystems, the study’s findings offer critical new insights into the major ecological roles small burrowing mammals play in grasslands.

“By maintaining a stable, low density of burrowing mammals using natural predators and ecological factors, we can promote sustainable livestock grazing practices while also preserving biodiversity and reducing human-wildlife conflicts,” Knops concluded.

More about small burrowing mammals

There are numerous small mammals that are adapted to a burrowing lifestyle. These animals are often found in grasslands, forests, and deserts where they dig tunnels and chambers for shelter, protection from predators, and access to food sources. Here are a few examples:

Moles

Moles are small mammals known for their digging capabilities. They have cylindrical bodies, velvety fur, tiny or invisible ears and eyes, and large, powerful forelimbs with broad paws adapted for digging. Their diet primarily consists of earthworms and other small invertebrates found in the soil.

Gophers

Also known as pocket gophers, these North American rodents are known for their extensive tunneling activities. They have cheek pouches, or “pockets,” which are used for transporting food back to their burrows. They have powerful front limbs that are excellent for digging.

Prairie dogs

Despite their name, prairie dogs are actually a type of ground squirrel. They are social animals and live in large colonies or “towns” in extensive burrow systems, which can have multiple entrances. They primarily feed on grasses, seeds, and roots.

Groundhogs (or Woodchucks)

These large rodents, part of the squirrel family, are excellent diggers, creating burrows with multiple entrances and chambers. They primarily eat vegetation and hibernate during the winter.

Rabbits and Hares

Many species in the Leporidae family dig burrows, especially the European rabbit. These burrows, also known as warrens, can be quite complex with multiple entrances and chambers.

Shrews

Some species of shrews are burrowers, especially those found in the genus Sorex. They are tiny mammals that primarily feed on insects and have been known to occupy the burrows of other small mammals.

Hamsters

In the wild, hamsters dig burrows that can be up to a meter deep, containing various chambers for food storage and nesting. They are omnivorous, with a diet consisting of a variety of foods, including seeds, fruits, nuts, and insects.

These are just a few examples of the many burrowing mammals found worldwide. Burrowing behavior has evolved in many different lineages independently, as it’s an effective strategy to avoid predators, harsh weather, and to store food.

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By Andrei Ionescu, Earth.com Staff Writer

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