We generally note that ‘stuff,’ including unwanted pests, make it to Hawaiʻi on Wind, Wings and Waves.
Some seeds, spores and insects arrived on the wind. A few birds flew or were blown off course; in them or stuck to their feathers were more seeds. Some seeds managed to float here on ocean currents or waves. Ocean currents also carried larval forms of fish, invertebrates, algae and other species.
Today, the pathways to paradise are diverse, including: air & ship cargo; ship hulls & ballast water; hand-carry/luggage; mail & freight forwarders; forestry activities; horticulture trade; aquaculture; pet trade; botanical gardens and agriculture experiment stations (or simply on you and your clothing.)
It is estimated that in the last 230+ years, as many as 10,000 plants have been introduced: 343-new marine/brackish water species; Hawaiʻi went from 0 native land reptiles to 40; 0 amphibians to 6 (including coqui frogs) and there is a new insect in Hawaiʻi regularly showing up.
With these pests, Hawaiʻi has the dubious distinction of being called the endangered species capital of the world and unfortunately leads the nation in endangered species listings with over 350-federally listed threatened or endangered listed species.
With only 0.2% of the land area of the United States, nearly 75% of the nation’s historically-documented plant and bird extinctions are from Hawaiʻi. We have more endangered species per square mile on these islands than any other place on Earth.
Impacts from invasive species are real and diverse: Quality of life that makes Hawaiʻi a special place; Forests’ ability to channel rainwater into our watersheds; Survival of native species found nowhere else; Health of residents and visitors; and Tourism and agriculture-based economy.
OK, other than negative impacts from the man in the mirror, there are a lot of nasty plants and animals that are wreaking havoc in Hawaiʻi. Unfortunately, many were brought here on purpose; at times, without much thought about the unintended consequences.
Let’s look at a few dubious examples of ‘good ideas’ gone bad.
While the sugar producers saw a marked reduction in the pesky rats in their plantation following the importation of mongoose (starting with a few in 1883) to inflict this outcome, these rodents also harmed the native ecosystem.
In less than two years after the importation of the mongoose, the rats were so diminished that it was and is now a rare thing to see a stick of cane that is eaten, and the plantations have so extended their plantations that they now grind nearly all the year, giving employment to double and treble the number of hands with a corresponding benefit to the trade of Honolulu. (Evening Bulletin, December 5, 1895)
“The drawback to the Mongoose is that he does not confine his menu to rats but varies it with all kinds of barnyard fowl and eggs and also ground-nesting game birds form a good part of his dietary. Another regrettable thing about him is that he is very fond of our field lizards or skinks which have an important part to play in the ‘balance of nature.’” (HA Baldwin – Maui News, August 5, 1921)
Unfortunately, the mongoose are targeting birds, including ground-nesters such albatross, petrels, boobies and shearwaters. They are considered to be the number one predator against the endangered Nene, eating the eggs and nesting females. They also eat the eggs and adults of many forest birds.
Another idea gone bad was the importation of fountain grass to be used as an ornamental plant around the house. It joins a long list of other invasive plants that were first used to decorate a yard or home that have since dominated the landscape and devastated our native flora.
First collected in Hawaiʻi in 1914, fountain grass has been introduced to many parts of the world as an ornamental grass. It is a poor pasture grass and a serious weed in many dry habitats.
Over 200,000 acres of the original site of the plantings (the Kona-Kohala side of the Big Island) are now dominated by this invasive weed. It’s a fire threat and first survivor that expands its cover by rapidly reestablishing itself after burning.
We also have concerns in the ocean, too.
Roi, a grouper, is another plan gone wrong. It was introduced to Hawaiian waters from Tahiti in 1956 to boost declining stocks for sport fishing, but never caught on as popular eating fish.
Added to that, roi is a high-risk fish for ciguatera poisoning. Roi, which prey on juvenile parrotfish and surgeonfish, have become the dominant inshore predator in the main Hawaiian Islands.
Its partner, taape, a snapper, was introduced to Hawaiʻi from French Polynesia about the same time (1955) for the same reasons (to enhance fishing opportunities) and shares the same sad results (at least in the opinions of many fishers.)
Introducers first thought that since there is the lack of native, shallow-water snappers in Hawaiʻi, it seemed like a good idea to fill a “vacant niche” for the sport fishers.
Taape generally do not share the same depth and feeding habitat with most native species (the natives are deeper in the water column,) overlaps little in diet and is not a frequent predator or prey of the natives. But some concerns remain (and the science differs from the negative attitudes from fishers.)
Unlike other Paciﬁc Islands, many people in Hawaiʻi don’t like to eat taape. Largely due to the size, color and lower values in the market, taape is a not often ﬁshed and has thrived.
With the rapid and dramatic increase in numbers of taape, concern has been expressed that it may be producing negative effects on populations of native food fishes or otherwise disrupting the existing fisheries for native species. (DLNR)
Finally, fortunately, we don’t have snakes … yet. I had the chance to visit Guam on several occasions and was given a tour of that island’s ‘snaky’ areas – it looks just like anywhere in rural Hawaiʻi.
While living in Kailua, every time I rode home on Kalanianaʻole Highway above Enchanted Lake above Kailua, with the overhanging haole koa, I was reminded it took us only 15-minutes to find a snake in Guam in this identical habitat. (In Guam, you unfortunately soon become aware of what it sounds like when there are no birds.)
There’s a long list of other ideas gone bad to our natural resources across the islands (I only mentioned a limited few, here,) in our forests, across the landscape, along our shores, in our streams and in the ocean. Before we bring in the next thing in, let’s think beyond the goal and consider the unintended consequences.