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Not every 'alien' species is a pest

April 27, 2008

Not every 'alien' species is a pest; some play vital roles in island life

By Norman Bezona

Exotic, or non-native, plants and animals are now being called alien species. Unfortunately, the term alien is one charged with negative connotations, with visions of pestiferous and otherwise uninvited crawlies that only Sigourney Weaver can conquer.

Or perhaps the word brings to mind some bulbous-headed creature from Mars. When the term is associated with humans, we almost automatically add "illegal" to create another negative picture. When we describe plants or animals as alien species, we may incorrectly think of aliens only as pest species.

However, every life form on our island is alien if one goes back far enough. Even species we identify as weeds are often "pioneer species" that are attempting to heal a wound that humans have created by mismanaging the aina.

Of course, it is essential to protect that which is unique to Hawaii, but we must be careful not to throw out the baby with the bath water. To simply label all the millions of life forms on this planet as native versus alien and then to infer that one is good and thus the other must be bad is a disservice to all.

What if the Alala (Hawaiian Crow) became established in say Puerto Rico, for example, as a viable population. Would it be appropriate to consider eradicating the alala because it was an alien species in Puerto Rico? Or let's turn things around. Puerto Rico has a parrot that is almost extinct. What if it did well here? Would we then consider eradication because it is not native here? These may be far-fetched examples, but many of the plants and sometimes animals introduced to Hawaii over the years are rare and perhaps even near extinction in the wilds from which they came.

I was very sad to hear that people were shooting parrots in Kona with the excuse that they are aliens and might someday become a pest.

One of the species under fire is the Patagonian Conure, which is endangered and protected in South America. To my knowledge the population of that species was only estimated to be 12 birds and our native Hawaiian hawks were doing a pretty good job reducing the population! Another example is a Rock Wallaby species that has been established and living in the Koolau Mountains on Oahu for almost 100 years. It is no longer found anywhere else and is thought to have become extinct in its original homeland. The population is less than 100 individuals.

Some examples of plants are the Royal Poinciana from Madagascar, the Dwarf Poinciana from Barbados, the Cabada Palm and, of course, many other palms, orchids and treeferns.

The Royal Poinciana, Delonix regia, also known as the Flame Tree or Flamboyant, may be found in tropical gardens worldwide, but in its own native habitat of Madagascar it is extremely rare in the wild. A palm of considerable popularity in Kona, the Cabada Palm, is thought to be extinct in the wild but was also a palm from Madagascar. Australia's Carpentaria Palm was thought to be extinct for over 100 years and then was rediscovered in a private garden in Darwin. It now graces Hawaiian landscapes. All 800 species of tree fern worldwide are now classified as endangered by international treaty since their rain-forest habitats are being destroyed.

So to label plants as native and alien is to oversimplify a very complex global ecosystem.

To infer that plants or animals are good or bad is dangerous. These are moral judgments. These terms are appropriate in relationship to how we manage and interact with the other living things around us. Yes, there have been plants introduced, many accidentally or illegally, that have had a negative impact on other life forms in a given environment. But for every negative impact, there is often a positive one. Non-native trees produce oxygen, sequester carbon and help control erosion just as do native trees, for example.

Plants and animals are like people in some respects. I have yet to meet a person that didn't have some good quality. The same is true of plants and animals. The Banana Poka is an example of a plant that, when improperly managed, has become a serious pest, especially in Koa forests. Some positive aspects are that our native honeycreepers are often observed feeding on the flower nectar. Basket weavers use the stem to make beautiful works of art that sell for big bucks. The fruit makes a delicious drink popular in Colombia and other parts of South America.

Another example is the pig which was introduced by Polynesians over 1,000 years ago. Even before its more robust cousin was introduced, this animal must have had a tremendous impact on Hawaii's forests. The positive side is they also supplied meat, and still do to this day, for many families here on the islands. It is important that we manage pigs so that they do not further damage critical and rare habitats, but total eradication would be a waste of valuable resources.

The much maligned mongoose does in fact eat rats, as several studies show. Despite the popular stories, the mongoose helps control our rat population and might even make it difficult for snakes to establish in our islands.

Unfortunately, being omnivorous, they also feed on ground nesting birds and almost anything else they can get into their voracious little mouths. Even with their bad reputation in Hawaii, I have always had a warm spot in my heart for the wily little mongoose because of Rudyard Kipling's Riki Tiki Tavi.

In other parts of the world, they have been of considerable benefit. If we could see the big picture, we might find that here, too, they have a value with proper management.

When the first humans arrived in Hawaii, well over 1,000 years ago, these islands had a very different ecosystem than in 1790 or today. There were many interesting birds but very few plants or animals that could help humans survive.

Most non-native plants introduced purposely have benefited man.

With diversified agriculture essential for our economic survival, it is important we don't hamstring ourselves so that we are unable to grow a crop that is of benefit to our community and economy by maligning all non-native species.

Our responsibility is to recognize that our community includes many other life forms, most of which are unique and need our special protection, and at the same time to recognize the need for non-native species including those introduced by the Polynesians.

It is vital that all of us with our diverse points of view work together for the benefit of our entire island community. We must beware of knee-jerk reactions and over-simplification of a very complex island environment.

The message for our future is that it is time for environmental groups, agricultural interests, the visitor industry and all other members of our community to work together on plans that focus on good management of our resources. These include native and non-native aspects of our island community.

This is a time when we can come together for the common good. It is not a time to be confrontational but to work for the good of the whole community whether it be plant or human for that matter. There is a lesson to be learned in how we treat all life forms in the islands. Maybe if we learn that lesson, we will treat one another better.

This information is provided by the University of Hawaii at Manoa College of Tropical Agriculture and Human Resources. For more information, contact the Cooperative Extension Service in Hilo at 981-5199, in Waimea at 887-6183, or in Kainaliu at 322-4892.

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