A Forest Without its Fauna
Dampa Tiger Reserve, located in the Lushai Hills of western Mizoram, is a protected area that is an ecological puzzle. Spanning a core area of 500 square kilometers, it was designated a tiger reserve in 1994 under India's Project Tiger. Yet, a comprehensive 2018 tiger census conducted across the country found no evidence of tigers within Dampa. This finding confirmed what many conservationists suspected: the reserve's apex predator had vanished.
The term scientists use for this phenomenon is "empty forest syndrome." The forest's structure—the trees, vines, and undergrowth—remains visually intact, but the large and medium-bodied animals that should inhabit it are absent or exist at extremely low densities. A 2014-2016 study using camera traps and transect surveys confirmed the presence of 40 mammal species, but the populations of large animals were perilously small. Species such as the Bengal tiger (Panthera tigris), Asian elephant (Elephas maximus), and sambar deer (Rusa unicolor) have been functionally eliminated from the ecosystem. This large-scale loss of animal life is known as defaunation. The primary cause is sustained illegal hunting, exacerbated by the reserve's proximity to the international border with Bangladesh.
Although a single tiger was photographically captured by a camera trap in May 2021 after a seven-year absence of sightings, this does not indicate a viable population. The reserve is a case study for understanding the ecological consequences when a forest loses its largest inhabitants.
Cascading Consequences of Absence
The disappearance of large mammals from Dampa has cascading effects on the entire ecosystem. This process disrupts fundamental ecological interactions that have evolved over millennia. One of the main impacts is on seed dispersal. Many tropical tree species depend on large herbivores and frugivores to consume their fruits and transport their seeds far from the parent plant. Without animals like elephants, gaurs, and large primates, the seeds of these trees fall directly below the canopy, leading to dense, localized clusters of seedlings that struggle to survive and preventing the trees from colonizing new areas.
This disruption alters the long-term composition of the forest itself. Plant species that do not rely on large animals for dispersal may gain a competitive advantage, potentially leading to a gradual shift in the forest's floral diversity. The absence of large predators also changes the behavior and distribution of smaller animals. While Dampa still hosts a population of clouded leopards (Neofelis nebulosa) and dholes (Cuon alpinus), their ecological roles are different from that of a tiger. The entire food web is altered, with consequences that scientists are still working to understand. Researchers continue to monitor Dampa to document the changes that occur when a seemingly healthy forest becomes ecologically hollow.