When visiting Kona, it will not be long before you will see small, slender, ferret-like animals scurrying across the road — particularly in the coffee belt along Mamalahoa Highway.
This little beast is the Indian Mongoose (Herpestes auropunctatus), a non-native species currently present on all major islands in Hawaii, with the exception of Lana’i and Kaua’i.
The mongoose was intentionally introduced into Hawaii in the 1880s for the purpose of controlling the rat populations that were damaging sugar cane crops. To the disappointment of plantation owners, the mongoose is diurnal (i.e. active during the daytime) and rats are nocturnal (active at night). As a result, the mongoose has had little, if any, impact on rat populations on sugar plantations or elsewhere on the islands. Worse yet, the mongoose has had a severe adverse impact on native bird species and other small animals.
On Rancho Aloha the mongooses hold our small flock of (very) free range chickens below a couple of dozen. The numbers of wild turkeys and Chinese pheasants on the farm are similarly reduced. A voracious and opportunistic predator, the mongoose feeds on both eggs and small chicks.
The mongoose in Hawaii provides an example of how an ill-considered biological control measure can make matters worse.