Control of the Indian Mongoose Herpestes auropunctatus on St John, US Virgin Islands / by Bruce E. Coblentz & Brenda A. Coblentz

Abstract

On several Caribbean islands in the late 1800s, Indian mongoose Herpestes auropunctatus were introduced to control black rats Rattus rattus. They have subsequently had a detrimental impact on native flora and fauna. Trials were initiated in January 1983 to test the effectiveness of short-duration, high-intensity trapping to control mongooses within localised areas of the Virgin Islands National Park (3,850 ha), St John (5,200 ha). Here, the major known impact of mongoose was predation of an estimated 23% of hawksbill turtle Eretmochelys imbricata eggs and hatchlings annually. Mongooses were live-trapped in various habitats (cactus scrubland to evergeen tropical forest) from January through November 1983, using 15 x 15 x 45 cm live traps baited with fish. Twenty locations were trapped (no indication of area given in original paper), with 12 re-trapped at least once. At each location, 8-14 traps were placed at approximately 30 m intervals in a line. Traps were set early in the morning and checked either the same evening or the next morning. In areas with high mongoose densities, traps were examined at least twice during each of the first two days. In total, 1,009 mongooses were trapped from January to November 1983. In the first two days of trapping, up to 24 mongooses were taken from 10 traps in a single day. It was estimated that an average of 86% of trappable mongooses were caught during the first 5 days of trapping in each area, with numbers further lowered by repeat trapping. Through the 11 months, trapping efficiency averaged 0.39 mongoose per trap day, decreasing in the four successive trapping periods (number of trap days/mongoose: period 1: 1.8; period 2: 3.0; period 3: 3.6; period 4: 4.3). Hawksbill turtles nesting at beaches where mongooses were trapped experienced no known loss of eggs or young to mongooses during the trapping period compared to up to 23% loss previously.