Mongooses for rat control

The Indian mongoose, Herpestes auropunctatus, was deliberately introduced into Pacific and Caribbean islands in the late nineteenth century for biological control of rats in plantation crops like sugarcane. This was a rare attempt at biological control by introducing a mammal to prey on another introduced mammal. One of the more colorful stories from the Hawaiian Islands is that a man known as "Mongoose" Forbes sold mongooses to sugar plantations as rat catchers in the 1870s. More scientific accounts suggest that the Indian mongoose was introduced to the Hawaiian Islands via the West Indies in the early 1880s. Whatever the story, the deliberate introduction of the mongoose for rat control was a badly flawed idea.

Modern twentieth century biological control programs screen potential introductions to make sure that desirable flora and fauna are not destroyed. This was not part of the scientific protocol in the nineteenth century when the mongoose was introduced for rat control. Even though mongooses eat rodents in sugarcane fields, they do not provide adequate rat control. One problem is that the mongoose is a diurnal hunter, whereas the rats they were introduced to control are nocturnal. Also, mongooses do not stay put in agricultural plantations. So there have been serious consequences for native species in native ecosystems.

From the islands of Fiji to the Caribbean, mongooses are predators of a wide range of native wildlife and a potential reservoir for diseases like rabies and leptospirosis. The ground-nesting quail dove (Geotrygon mystacea) was nearly eliminated from the Virgin Islands by mongoose predation. Hawaii's endangered state bird, the nene or Hawaiian goose (Nesochen sandvicensis) is attacked by the mongoose, as are the endangered Hawaiian dark-rumped petrel (Pterodroma phaeopygia), Newell's shearwater (Puffinus newelli), and the Hawaiian crow (Corvus hawaiiensis). Turtles, native lizards, snakes, and poultry are also mongoose prey. Live traps, hunting, and poison baits are among the mongoose control methods available.

The bad experience with mongooses did not extinguish Hawaii's interest in biological control of rats. In the late 1950s, Hawaii introduced barn owls (Tyto alba) for rodent bio-control. Even dogs have been used to hunt rodents in sugarcane fields. Trapping tends to be too labor intensive for large outdoor areas with rats. Early in the twentieth century almost 150,000 rats were trapped annually in Hawaii's sugarcane plantations with no noticeable effect on rat populations or crop damage. Shooting is also of questionable value for rat control. So, poison baits have been the fallback for keeping rat populations under control.

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