Cover photo: The Bolivian chinchilla rat (Abrocoma boliviensis), an endemic rodent of Bolivia and critically endangered. Photo: Marisol Hidalgo
“Most people don’t know much about native wild rodents, their importance in ecosystems, or their role in ecosystem services that benefit people. But when you start to explain, they are surprised,” says Adriana Rico, Ph.D. in ecology and director of the Institute of Ecology at the Universidad Mayor de San Andrés. In an interview with Armonía, Rico explains the fascinating world of rodents and why it is important to conserve the 148 species of native rodents known in Bolivia to date.
Rodents have earned the right to be in this world
Rico emphasizes that rodents, despite being less charismatic and less known, play a crucial role in ecosystems. Although some people may consider them less relevant, she argues, “If we talk in evolutionary terms, rodents have earned their right to be here, just like us. Who are we to decide which species have more right to exist than others?”
People should care about conserving rodents because they are part of the base in food webs in ecosystems. The ecologist explains that if that base were to be missing, problems would arise in higher groups, that is, in predators. “They really don’t seem important, but if the other animals don’t have food, there will be a problem. It is a fairly intricate network of relationships in nature, plants, animals, and different levels. One problem in one network disrupts everything,” she points out.
The role of these small mammals is very varied. Some are specialized insect predators and are very good pest controllers, others can disperse seeds and spores, thus contributing to forest regeneration, and they even contribute to pollination and serve as prey for various wild carnivores.
Thus, these animals are important for ecosystems. “Many rodents dig burrows, and this serves to aerate the soil. Through the tunnels they make, they move the earth and generate the removal of organic matter, they loosen the soil. When it is very compacted, it is difficult for plants to root,” Rico points out.
Squirrels are also rodents. In Bolivia, there are three species of squirrels. Studying and collecting them is complicated due to their arboreal lifestyle, as they are very clever and elusive. “Further studies are needed to determine their taxonomic systematics. They love to hide seeds as a form of storage, but eventually they can forget where they hid them. So, in a way, they also contribute to seed dispersal for subsequent germination. They have a very interesting role,” says the biologist.
Key Biodiversity Areas for the protection of wild rodents
Rodents are the most diverse group of mammals in practically every part of the world, and Bolivia is no exception. With 148 species, rodents are the most numerous group of native mammals in the country. However, Rico points out that Bolivia also has native rodents that are in some category of threat, such as some species of the genera Akodon, Kunsia, Thomasomys, Oxymycterus, Abrocoma, Dinomys, and Ctenomys, among others, where the Chinchilla chinchilla is in a critically endangered state of conservation. Bolivia also harbors many rodent species that are endemic to the country, such as Abrocoma boliviensis, Oxymycterus hucucha, several species of the genus Akodon, or the genus Ctenomys, among others. The expert also suggests that as more research is conducted on these small mammals, we could discover even more endemic species in the country and/or more rodent species with some degree of threat.
Rico emphasizes that the criterion of endemism is key to the conservation of biodiversity and that responsibility towards these endemic species is fundamental, as several of these species found only in Bolivia are threatened by habitat loss. She highlights the need to continue researching and protecting these particular and little-known species, emphasizing that their preservation is not only essential for maintaining biodiversity but is also a commitment and responsibility to nature and its balance. In this sense, the ecologist highlights the value of Key Biodiversity Areas (KBAs) because they focus on the most vulnerable species to extinction and can raise awareness among people. Consequently, KBAs could be of interest in securing funds for research.
The relationship of rodents with human health
Beyond the importance of rodents in ecosystem services, these animals are also crucial in public health and ecosystem balance. According to Rico, rodents can transmit diseases to human populations such as hantavirus, salmonella, or leptospirosis, although, to be precise, these transmissions are rare and mainly occur in rural or wild environments affected by human activities, where rodents can come into contact, and where lack of order and hygiene are key factors for contagion to occur.
“It’s a matter of hygiene,” comments Rico. The presence of rodents in human environments is usually more common in places with poor hygiene habits. Maintaining a clean and tidy environment significantly reduces the risk of rodent-transmitted diseases. However, the biologist fundamentally emphasizes that the most important thing is to maintain the population balance of rodents in nature. An excessive increase in their number, known as “rat outbreak,” can occur due to factors such as the elimination of their natural predators or drastic changes in the environment (Such as deforestation or wildfires) and this could increase the chances of diseases among them and potentially their transmission to other species, including humans. Similarly, the population reduction of some species could trigger an increase in others, also potentially causing an increase in diseases and pathogens, some of them zoonotic.
“Population cycles are normal,” explains Rico, highlighting that these regular cycles of increase and decrease are linked to resource availability and predator pressure. However, when these cycles shoot up abnormally, it can be indicative of environmental imbalances that affect rodents, their predators or even human communities.