The Indian Bullfrog, a relatively recent immigrant from the mainland, is progressively infiltrating the island’s ecosystem and ominously impacting the local economy. But the bullfrog is not the only alien species found here. A myriad of others, including elephants, chital, hog deer, barking deer, and the Giant African Snail, are also wreaking havoc on the island’s fragile balance.
The Definition and Impact of Invasive Species
The term ‘invasive species’ refers to organisms that are unintentionally or deliberately introduced into an environment where they don’t naturally occur. Often, they flourish due to the lack of natural predators, triggering an imbalance in the ecology. This leads to significant economic and environmental damage. Islands, in particular, are extremely vulnerable to these intrusions as they host unique creatures which can’t be replaced. These endemic beings exist nowhere else in the world, forging an exclusive food chain vastly different from that found on the mainland.
While resources are limited and natural calamities frequent, island-species have evolved better disaster resilience. However, rapid human-induced impacts tend to overwhelm their adaptability. The Convention on Biological Diversity indicates that invasive species contribute to 40% of all animal extinctions recorded since the 17th century.
International Guidelines in Managing Invasive Species
The International Union for Conservation of Nature (IUCN) has developed specific guidelines to manage invasive species, particularly on islands. Emphasis is placed on data gathering, community involvement, policy implementation, and management plans. Surprisingly, India is among the few countries in the world that lacks a comprehensive policy for managing invasive species.
Anatomy of the Indian Bullfrog
Scientifically named Hoplobatrachus tigerinus, the Indian Bullfrog, also known as the Bull Frog, Golden Frog, Tiger Frog etc., falls under the ‘Least Concern’ category according to the IUCN Red List. Hailing from countries like Afghanistan, Bangladesh, India, Myanmar, Nepal, and Pakistan, they are protected by the Indian Wildlife Act 1972, listed under Schedule IV.
The Invasion of the Indian Bullfrog
Following the decline in natural fish stock after the 2004 Tsunami, authorities encouraged integrated farming, incorporating aquaculture into agricultural ponds. Unfortunately, some fishling stocks sourced predominantly from Kolkata and released into these ponds were infested with bullfrog eggs and tadpoles. This appears to have triggered the advent of the bullfrog on the island.
Consuming anything that fits their jaws, from centipedes, native frogs, lizards, small snakes to even chicks and ducklings, bullfrogs pose a considerable threat to the island’s food supply. Furthermore, adult bullfrogs jeopardize smaller endemic vertebrates. Not only do they consume the native frogs, but their similar diets also suggest a potential competition between species.
