Ocean Watch

A reader writes, "On my walks, I have been seeing quite a few mongooses (mongeese?). Do they have any natural predators in Hawaii? What keeps the population in check? Since you occasionally venture onto terra firma in your column, maybe you could do an article about these creatures."

I do occasionally stray inland in this column, but usually it's up a stream or down a beach. When I go too far into the interior, my editors take notice. I once wrote a story about watching Alaska grizzly bears eating salmon. On the day the piece was supposed to run, I found a news item in its place. I called the newsroom. "Your column is called 'Ocean Watch,'" I was told. "It should have something to do with the ocean."

Oh. OK. Back in 1872 a man named W.B. Espeut got the idea that Indian mongooses might take care of the rat problem in Jamaica if turned loose in the sugar cane fields there. So he sailed across the ocean to Calcutta on a ship called the Merchantman, captured four male and five female mongooses (one pregnant) and brought them back across the ocean to Jamaica.

Twenty years later, in a journal article, Espeut gave the mongooses rave reviews. Besides killing rats, he wrote, "snakes, lizards, crabs, toads and the grubs of many beetles and caterpillars have been destroyed."

Espeut's paper captured the interest of Hawaii sugar planters, but not everyone was convinced that importing mongooses was a good idea. In an 1883 issue of Planters Monthly, someone wrote, "Whether it would be wise to introduce the animal to these Islands may be a question. It would be important to first learn more of the nature of the creature, for they may prove an evil."

Unfortunately, no one heeded this anonymous writer's advice. That same year, 72 Jamaica mongooses were loaded onto a ship and sailed to the Hamakua Coast of the Big Island. Later, offspring of these animals were released on Maui, Molokai and Oahu. One story says that Kauai people didn't want mongooses on their island, and when a shipment reached there, the animals were thrown overboard in the harbor and drowned. To this day, Kauai hosts no mongooses.

But the other islands have them and it's been a disaster.

Mongooses do eat rats, it turns out, but not enough to control rat populations. Sugar crops on Maui, Oahu, Molokai and the Big Island suffered as much economic damage from rats as those on Kauai. Far worse is the mongoose appetite for ground-nesting birds and their eggs. Our much-loved nene, or Hawaiian goose, nearly became extinct due to mongoose predation. Mongooses also wiped out Newell's shearwaters on Oahu, Molokai, Maui and the Big Island.

Because Hawaii hosts no natural predators for mongooses, they have to be trapped or poisoned to keep their populations in check. Getting rid of them completely is nearly impossible. They are as much survivors as the rats they were brought here to eliminate.

All the mongooses in Hawaii today are descendants of those first nine animals brought to Jamaica. Females bear from one to three pups twice a year.

Mongooses (and rats) can carry a potentially lethal disease called leptospirosis. The bacteria are transmitted to humans through infected animals' urine that gets into ponds and streams -- which, of course, all eventually run into the ocean.