Induced Estrus in Female Small Asian Mongooses (Herpestes javanicus) for the Purpose of Controlling Invasive Alien Species in Okinawa Island

Abstract

The small Asian mongoose (Herpestes javanicus) belongs to the family Herpestidae, order Carnivora, and originally inhabited Iraq through northern India to extreme southern China and Indonesia, the Malay Peninsula, Hainan, Java (Nowak 2005). Mongooses, including small Asian mongooses, have been widely introduced by people to exterminate rats for pest control (Yamada and Sugimura 2004). In Japan, small Asian mongooses were introduced to eliminate yellow-spotted pit vipers (Habu snakes; Protobothrops flavoviridis) and sugarcane rats on Okinawa Island in 1910 and Amami-Oshima Island, Kagoshima Prefecture in 1979 (Yamada 2002). Naturalized and overbred mongooses, which prey on insects, reptiles, small mammals, wild birds and domestic fowl, have impacted the poultry industry, and threaten the survival of rare endemic species, such as the Amami rabbit (Pentalagus furnessi), Okinawa rail (Galirallus okinawae) and so on (Yamada 2002). A mongoose eradication project led by the Ministry of the Environment, Government of Japan, has been conducted on Amami-Oshima Island since 1996 and northern Okinawa Island since 2000. Moreover, mongooses were designated as invasive alien species by the Invasive Alien Species Act in Japan (Ministry of the Environment, 2004); however, the eradication project has not yet succeeded. The distribution of mongooses has expanded on Okinawa and Amami-Oshima Islands and, in addition, mongooses were found in Kagoshima city (Kyusyu Island) in 2007. Currently, cage-type traps and cylindrical trapping with bait, chicken meat, have been mainly used for capturing mongooses on Okinawa and Amami-Oshima Islands. Mongoose-drawing techniques require a more effective for increase of the capture number. For effective capture, studies searching for and identifying attractant substances for species-specific capture have been performed in small Asian mongooses, and the previous study attempted to identify volatile fatty acids from anal sac secretions in this species (Ogura et al. 2000b). In the present study, to establish a trapping method with an estrous female or its excreta, we tried to create a protocol to artificially induce estrus in female small Asian mongooses using exogenous hormonal treatment. Estrus was determined based on the profile of urinary estrogen concentrations.