‘Small herbivores are true victims’

India’s natural areas are under assault. Extensive land-use changes have left ecosystems fragmented, depleted, and invaded by a staggering array of alien plants. Two-thirds of these precious spaces now grapple with this insidious threat, putting biodiversity at immense risk. Among the most vulnerable are herbivores, both wild and domestic, who rely on these landscapes for their very survival.

While invasive plants are not a primary food source for any herbivore, the story is surprisingly nuanced. Large grazers like rhinoceroses, Indian bison and sambars have been observed consuming them, particularly during dry seasons. Driven by factors like size, health and nutrition, these interactions are complex and far from a simple meal.

Large-bodied herbivores, also known as megaherbivores, play a crucial role in this tangled web. By virtue of their size and varied diets, they can clear swathes of vegetation, including invasive plants, creating opportunities for new growth. In places like Kaziranga and Manas, this “gardening” has led to a reduction in invasive species. However, the story takes a turn in drier regions. Here, invasive trees like Lantana camara and Prosopis juliflora have established an impenetrable fortress. Unable to break through these thorny thickets, megaherbivores turn to native plants, adding pressure on already struggling population. Even worse, some, like elephants, unwittingly promote the spread of invasive species by eating on their fruits and dispersing their seeds.

The true victims are the smaller and medium-sized herbivores. Heavily reliant on grasses, shrubs and forbs, which are decimated by invasive plants, these creatures face a stark choice: Starve or consume the invaders. While the long-term health effects of such a diet on wild animals remain unknown, cases of liver damage, allergies and even respiratory disorders have been documented in domestic herbivores.

Fortunately, glimmers of hope remain. Protected areas across India are actively battling back. Through meticulously managed designated grasslands and periodic removal of invasive plants, wildlife sanctuaries provide temporary havens for herbivores. But these measures are a band-aid, not a cure. The long-term solution lies in large-scale, science-driven restoration of native ecosystems.

Ninad Avinash Mungi is a post-doctoral research scholar at the Center for Ecological Dynamics in Aarhus University, Denmark

This column was first published in the January 1-15, 2024 print edition of Down To Earth