Look out your window. Upcountry, you may see eucalyptus trees or fireweed. At lower elevations, you may see miconia or hear the repetitive call of the coqui frog. To many of us, these may seem like the sights and sounds of normal Hawaiian flora and fauna. They are, however, all considered to be invasive species.
Lissa Fox of the Maui Invasive Species Committee (MISC) spoke at the Upcountry Sustainability public meeting on Monday, Oct. 3. "Not all non-native species are invasive, and not all invasive species are non-native," she explained.
MISC defines an invasive species as one that causes harm to the integrity or function of the watershed or environment. Maui's island ecosystem is especially vulnerable.
Oh deer! These adorable relatives of beloved Bambi may enjoy grazing in this field above Makawao, but these Axis deer found throughout Maui, which reproduce at exponential rates, not only pose a danger to Upcountry drivers but are considered to be an invasive species due to the major monetary damage they cause to commercial crops, personal property and landscaping—especially golf courses. The Maui Axis Deer Working Group has proposed an organized, humane, deer culling operation.
Photo: Ben Ladd
"These creatures can directly impact our daily life," said Fox. "Coqui frogs can decrease a home's value by 18 percent. When selling your land, if you've ever had Little Fire Ants, it is mandatory to disclose this to potential buyers."
MISC tackles both existing invaders and potential threats. Miconia, which crowds out native plants and groundcover, causes erosion of soil into the watershed. Originally introduced for landscaping, miconia's microscopic seeds are easily transported. MISC hopes to find a natural insect predator to safely control the population.
Physical removal is "an amount of work that is not sustainable," said Fox.
The Little Fire Ant is another potential threat. One of the smallest ants in existence, these insects form "super-networks" of cooperating colonies that spread quickly across a variety of landscapes.
"They spread plant diseases, they sting people, and they blind animals," said Fox. "They're pretty scary."
With no known predators, these ants have yet to be spotted on Maui, aside from one contained incident in Waihe'e late last year. But Hawai'i Island has suffered a massive infestation.
"I don't have much hope for the Big Island," said Fox. "But I think we're capable of stopping them from coming here."
MISC urges residents to report any unusually small, yellow, stinging ants immediately. They also recommend buying local plants and flowers whenever possible.
Anne Gachuhi of the Home Garden Support Network provided a crash course in creepy-crawlies that target vegetables and fruits. Aphids, for example, eat greenery, reproduce exponentially, attract ants, and promote sooty mold. Caterpillar species chew holes in leaves and burrow into the heart of fruits and vegetables to lay eggs.
And many of these common garden invaders reproduce so rapidly that they quickly become resistant to chemical insecticides.
"The best way to control the damage is to support the pests' natural enemies," said Gachuhi.
For example, native parasitic wasps prey on the harmful insects, while not damaging the crop itself.
Gachuhi recommends maintaining crop diversity, planting crops that attract the natural predators of troublesome pests, and practicing sanitation by cleaning up plant litter.
Mark and Leah Damon shared a sobering update on the varroa mite threat to the honeybee population of Hawai'i. They warned that Maui could lose its entire population of feral bees to this easily spread mite, and urge citizens to start keeping their own hives.
"The only bees that can survive a varroa mite attack are the ones managed by humans," said Mark. "The mites are easily controlled by safe chemicals like formic acid."
Without enough honeybees, agricultural crops will not be pollinated sufficiently, and crop yield will be severely affected.
"Maui is the easiest place in the world to keep bees," added Leah.
Fox, Gachuhi and the Damons believe the strict inspection and quarantine of high-risk items shipped inter-island is the top priority.
"We're the reason these species are being spread," said Fox. "We need to be a lot more careful."
At the end of the meeting, Lokahi Sylva and Phyllis Robinson discussed growing concerns regarding the largest invasive species on Maui-Axis deer.
"Eight deer were brought here 53 years ago," said Sylva. "In the warm, predator-free environment of Maui, their population has increased to well over 12,000."
With no natural predators on the island, they are free to continue reproducing exponentially, with 90 percent of females over a year old giving birth to one fawn every year, according to Sylva.
Axis deer cause major monetary damage to commercial crops, personal property and landscaping-especially golf courses. They are also a danger to drivers, particularly on Upcountry roads.
Sylva and Robinson, in collaboration with the Maui Axis Deer Working Group, proposed an organized deer culling operation. In their model, trained, certified hunters- Feral Ungulate Removal Specialists (FURS)-would harvest deer from carefully selected areas of the island, usually at night. They would prioritize humane hunting and complete utilization of the meat.
But currently, it is illegal to sell venison that doesn't carry the USDA stamp. In order to be USDA-approved, the animal has to be inspected by a USDA officer both before and after slaughter. This would be difficult to facilitate when hunting deer in the wild. Sylva and Robinson continue to research and communicate with specialists and government representatives.
"The deer are an increasing risk to public health and safety," said Sylva. "They are also a readily available source of protein for Maui's human population."
Although a good number of invasive species are here to stay, prevention and management of the most devastating species will take the vigilance of every Maui resident.
To find out more, visit www.hawaiiinvasivespecies.org/iscs/misc.