Varanus Indicus - Contact With Humans

Contact With Humans

Humans have introduced the mangrove monitor to a number of Pacific Islands since the 1930s. They have been present on Ifaluk in the western Caroline Islands since the Second World War. The Japanese introduced the lizards to the Marshall Islands prior to World War 2 to eliminate rats; the lizards flourished and soon began to raid the local chicken houses. When American troops arrived, the locals asked them for help in getting rid of the mangrove monitors. The US response was to introduce the marine toad (Bufo marinus) which proved toxic to the lizards. As the monitor population dropped, however, the rat population began to rise. Marine toads were introduced to the Palau Islands for a similar reason, and the demise of the mangrove monitors led to an increase in numbers of beetles known to be harmful to coconuts.

The mangrove monitor is hunted in many places for its skin which is used for leather in making drum heads. Although international trade in this species is small, Mertens referred to it as one of the most heavily exploited monitor lizards. In 1980 trade in over 13,000 monitors was declared. However in many remote places they are used as a food source and are killed because of their reputation for preying on domestic animals. There is an ethnic group on Guam that eats the monitors as a traditional food and a business exists there that sells monitors for food.

The United States Department of Agriculture’s Animal and Plant Inspection Service division, announced that it will use a combination of two poisons, diphacinone and brodifacoum, to kill off the rodents on Cocos Island. They will also attempt to lower the mangrove monitor population on Cocos Island by 80%, using a myriad of trapping methods proposed by herpetologist Seamus Ehrhard, as the lizard is believed to prey upon the endangered Guam Rail (Gallirallus owstoni). Most locals, however, do not see the monitor as an invasive species and a few activists are opposed to the attempt to lower the population on Cocos Island.

Mangrove monitors are often kept in zoos and private collections as they are an active and alert animal that generally can be handled if tamed properly. Most specimens defecate on their handlers when stressed. With proper care they can live up to 20 years in captivity.