Hoplobatrachus tigerinus

The Indian bullfrog is native to mainland Afghanistan, Bangladesh, India, Myanmar, Nepal, and Pakistan, as well as possibly Bhutan and China, although its presence is uncertain.[1] It has been introduced to Maldives,[1] Madagascar,[7] and India's Andaman Islands, where it is now a widespread invasive species.[8] Likely areas to be invaded in the future include the Mascarene Islands, Malaysia, Indonesia, and East Africa.[9]

First reported in October of 2011,[10] H. tigerinus has become a major threat to the fauna of the Andaman Islands. Larger than native frogs, it can easily consume large numbers of them, along with reptiles such as the Andaman worm snake and Andaman day gecko, as well as centipedes. The rapid spread of this frog throughout the archipelago is harmful to human residents as well, having disastrous effects on the local economy. The bullfrogs frequently kill and eat residents' fish and chicks, both of which are important to the islanders. While Indian law prohibits their killing, it is still done, both out of desire to rid the islands of the species and for food (H. tigerinus is a very cheap source of protein). Despite these efforts, the frogs' spread continues.[8]

One trait in particular that facilitates this invasion is the carnivorous nature of H. tigerinus tadpoles. Experimentation at the Andaman Nicobar Environment Team (ANET) field station on South Andaman Island demonstrated that when kept together in pools with adequate amounts of food, Indian bullfrogs rapidly devoured the tadpoles of native species. This behavior did not appear to increase their growth rate, the time it took to metamorphosize, or adult size. They consumed other tadpoles so quickly that no competitive behavior could be observed between different species. Even when kept only with their own kind, their aggression towards other tadpoles remained, with only three surviving per pool on average (for comparison, when kept without bullfrogs, native tadpoles—of the species Microhyla chakrapanii and Kaloula ghoshi—lived to metamorphosis three out of four times, on average). It is likely that the frog will eventually reach the Nicobar Islands.[11]

The species was first introduced to Madagascar for food, for which it is still used, although it has now become a pest. Human consumption has not been enough to prevent its spread.[1]

Hoplobatrachus tigerinus is typically found in freshwater environments, especially wetlands, such as paddy fields. It is not generally found in other ecosystems, such as forests and coastal areas.[1]

Adult Indian bullfrogs eat invertebrates, small mammals, and birds.[1] Tadpoles are known to consume mosquito larvae, including those of the species Aedes aegypti and Culex quinquefasciatus.[12]

Hoplobatrachus tigerinus reproduce during the monsoon season, in pools of rainwater. They produce many eggs at one time, although many tadpoles die before reaching adulthood.[1] They can live over seven years in the wild.[13]