Kauai Invasive Species Committee

People from all walks of life are drawn to gorgeous Hawaii. But human outsiders are not the only transplants eager to settle down there. The mongoose is one of the most detested of these invaders. It has wreaked havoc on native birds on Maui, Oahu and Molokai for more than a century, and now, it seems, it is spreading. For the first time, one of the creatures has been trapped on Kauai.

“We’ve been sounding the alarm for years, but it’s a very difficult thing to prove,” said Keren Gundersen, the project manager for the Kauai Invasive Species Committee, the University of Hawaii project responsible for bagging the mongoose. “It’s a game changer to actually trap one,” she added.

Ms. Gundersen’s group was just reaching the tail end of its funds for a mongoose-trapping initiative when it began hearing from locals who had spotted the elusive little carnivore darting around the Kauai Lagoons resort. They set dozens of live traps and relentlessly monitored them. Two months later, their efforts paid off. They trapped a mongoose.



Like so many invasive species that now run amuck on islands around the world, mongooses were intentionally introduced to Hawaii. Sugar cane farmers took their cue from Jamaican plantation owners who imported mongooses to control rat populations. In 1883 the mongooses were let loose in the fields, an approach that proved to be colossally uninformed. As it turns out, rats are nocturnal and mongooses are diurnal. The exotic predators never came in contact with their rodent prey, and native bird populations began crashing instead.

Today, mongooses continue to gobble their way through native nestlings and turtle eggs. Mongoose-proof fencing and costly eradication programs are the only way of keeping the creatures out of nature sanctuaries and reserves.

Kauai never introduced the mongoose, however, and so was spared much of the carnage. Still, many have caught the occasional glimpse of gray-brown fur or of a furry tail, with about 70 sightings reported in the last 10 years alone. Sporadic trapping efforts continued to yield nought. Mongooses only live about six years, so Ms. Gundersen suspects Kauai now hosts an established population.

Mongooses are smart animals, she said, and if prey are abundant they will avoid traps. At this point, there is no way of knowing how many mongooses may be present on Kauai or how they arrived there.

The trapped mongoose, a mature male, was humanely euthanized before its body was sent off for testing, the group said. Ms. Gundersen hopes that genetic analysis will show whether the mongoose came from one of the other islands. In the meantime, her group is bolstering its mongoose monitoring and asking locals to keep an eye out for the animals.

“I don’t know that equilibrium with a mongoose would be possible without extirpation of many native birds,” she said. “We have a lot to eat over here. We definitely should be worried.”

An earlier version of this post misspelled the name of a Hawaiian island; it is Molokai, not Mokolai.