Vertebrate Pest Conference Proceedings collection


Date of this Version

March 1967


At Eniwetok Atoll in the Marshall Islands, rats have been involved in an intriguing story. Polynesian rats were probably the only rodents present until after World War 11 when roof rats were brought in along with supplies and equipment for the atomic test program in the late 40's or early 50's. Some islets of the atoll, originally covered with coconut plantations, were denuded by heat, shock, and tidal waves following the detonation of devices. Initially radiation levels were high, but radioactive decay and dilution reduced the radiation hazard, and today the background radiation is well within the safe range. Many of the studies of rodents at Eniwetok have been centered on an island 2 3/4 miles from the site of several of the larger explosions. Probably the Polynesian rat population was exterminated by the blast which denuded this island. Sometime during the early days of the test program, the roof rat was accidentally introduced with supplies or equipment and quickly populated the island. Some survived the tests, probably by being in protected cable tunnels or under concrete structures, being able to scavenge enough food, and existing through the initial period of heavy radiation. Today, more than a decade after the tests, the islands have recovered remarkably; dense vegetation grows to 20 feet in places. No genetic damage is apparent in either the plant or animal populations. The rats are healthy, normal appearing animals. Any mutations which may have resulted from radiation exposure have either been lost from the population or are not readily apparent when examining the animal grossly. All over the atoll the scars left from the testing program are being covered with remarkable speed. The resiliency of the biologic community surprised some observers.