The small Indian mongoose (Urva auropunctatus) was introduced to Okinawa Island in 1910 as a countermeasure to damage caused by snakes and wild rats. However, their presence has led to declines in the populations of many unique endemic species. Okinawa Prefecture and the Ministry of the Environment of Japan began installing traps in the Yambaru forest area in 2000 that have successfully reduced the mongoose population. Detection dogs were adopted in 2012, after the effectiveness of mongoose traps declined in low-density areas.

Using data from the mongoose countermeasure project (2013 - 2016) provided by the Department of the Environment of Japan’s Okinawa Prefecture Nature Conservation Division, we compared the results for intensive capture areas (traps plus detection dogs) and non-intensive capture areas (traps only). Factors such as TD (Trap Days), CPUE (Catch Per Unit Effort), number of captured mongooses, and the individual characteristics of captured individuals were assessed in these areas, and the effectiveness of detection dogs was examined. The CPUE decreased year-on-year in the intensive catch areas. Most of the mongooses captured using detection dogs were adult females. The mongoose population has been reduced and held successfully at low levels in trap capture areas where detection dogs are also used. It seems unlikely that the mongoose population can be reduced by trapping alone. The detection dogs appear to have contributed significantly to the observed population reduction by raising the capture rate of fertile adult females.