Native Hawaiian Species
Native Hawaiian Species
Hawaiian Hoary Bat (Lasiurus cinereus semotus)
Hawaiian Name: ‘Ōpe‘ape‘a
Status: Endangered Species. Found on Kaua‘i, O‘ahu, Maui, and Hawai‘i Island.
[Illustration: Hawaiian hoary bat]
Imagine a mouse with wings, flying erratically through the air. That’s a good approximation of the Hawaiian hoary bat, the only native Hawaiian land mammal and one of the rarest bats in the world.
A distinct subspecies of the North American hoary bat, the Hawaiian hoary bat weighs about 6 ounces (.2 kg), with a body that is about 3½ inches (9 cm) long, and a wingspan of nearly 14 inches (36 cm).
White-tinged ears give the Hawaiian hoary bat a frosted or “hoary” appearance. The bat’s coat is reddish-gray and brown, in contrast to continental hoary bats, which have more of a grizzled, brown appearance and are highly migratory, which explains how some of the bats may have reached the Hawaiian Islands an estimated tens of thousands of years ago.
The continental hoary bat established a population in the Hawaiian Islands that eventually evolved into a unique (and isolated) subspecies that is now endemic to the Hawaiian Islands.
The Hawaiian hoary bat has evolved to maneuver in the Hawaiian Islands’ densely vegetated habitat, and now weighs just about half of what its North American relative weighs. The Hawaiian bat’s fast-beating wings are also shaped differently, allowing it to dart to and fro through the air chasing insects.
The Hawaiian hoary bat is a year-round resident of the Hawaiian Islands, yet it still builds up a fat reserve in late summer—this is a remnant trait of its origins as a migratory species. The Hawaiian hoary bat roosts in trees, and gives birth in early summer, usually to twins.
An ancient Hawaiian saying states: “Aia ko kāne i ka lawai‘a, ho‘i mai he ‘ope‘a ka i‘a.” (“Your husband has gone fishing and returns with bats for meat.”), which is a saying that “comes from a children’s chant of amusement for coaxing a sea animal to crawl from its shell.”[i]
The Hawaiian hoary bat is nocturnal (active mostly at night), usually leaving its roost before sunset and then returning before dawn. Darting back and forth rapidly through the air, the bat feeds on flying termites, moths, and other insects, including hard-bodied insects like beetles, which the bat crushes with its powerful jaws.
The Hawaiian hoary bat uses echolocation, emitting a series of high frequency sounds (beyond the range of human hearing) that bounce back from objects and then are interpreted to help the bat “see” using sound.
The Hawaiian hoary bat is found mostly on Kaua‘i and the island of Hawai‘i, but is also occasionally seen on O‘ahu and Maui. The bats may be seen in many different habitats, from mountain rainforests to coastal plains.
The Hawaiian hoary bat is often seen at dusk over nearshore waters (e.g., in Hilo on the island of Hawai‘i, and Hanalei and Waimea on Kaua‘i). The bat is preyed upon by the native ‘io (Buteo solitarius, Hawaiian hawk) as well as the native pueo (Asio flammeus sandwichensis, Hawaiian owl).
Hawaiian hoary bat populations are thought to be fairly localized. It’s unclear how much transportation (migration) takes place between Hawaiian Islands. Relatively little research has been done on the bats and particularly little is known about their mating habits and how they raise their young (known as pups).
Another species of bat may also have once lived in the Hawaiian Islands, but is now extinct. The ‘ōpe‘ape‘a was listed as an endangered species in 1970. Researchers are currently working to learn more about the bat to aid recovery efforts.
[Photograph: Hawaiian hoary bat]
Hawaiian Damselflies and Dragonflies
Hawaiian Names: Damselfly: Pinao
Dragonfly: Pinao ‘Ula
[Illustration: Damselfly and Dragonfly]
With large, compound eyes, lace-like wings and bodies that range from bright turquoise-blue to brilliant yellows and reds, Hawaiian damselflies and dragonflies are quite a sight to see close up.
They are skilled predators, able to navigate sharp turns as they reach out with their front legs to catch smaller insects on the wing. Then, while still in flight, they eat their prey and begin the search for their next victim.
The Hawaiian Islands have at least 23 endemic species and subspecies of damselflies (all in the genus Megalagrion), as well as three introduced damselfly species.
The body of the damselfly is divided into three main parts: the head, thorax, and abdomen. At the front of the head is the mouth, which includes a pair of jaw-like mandibles that the damselfly uses to chew its prey.
Behind the head is the thorax, which consists of three fused segments, each supporting a pair of legs. The two hind sections of the thorax are connected to the damselfly’s four long, narrow wings.
The veined wings of the Megalagrion damselfly are transparent when the insect is young, but darken into an amber hue as the insect ages. The two largest segments of the damselfly’s legs—the femur and tibia—are lined with spines that are used to grasp prey.
The damselfly’s two large eyes are composed of multiple tiny facets that provide a wide range of vision. Three smaller eyes (ocelli) are arranged in a triangular formation atop the head, helping the airborne damselfly to sense light levels and maintain equilibrium. The damselfly’s sense of smell is received through hair-like antennae that also assist in flight.
The larval stage of the damselfly is typically spent in freshwater streams or along stream banks, where many water insects feed. The larval damselfly looks somewhat similar to the mature damselfly, but without wings and much shorter.
Larval damselflies also have a lower mouth part known as the labium, which unfolds outward from beneath the insect’s head. The tooth-tipped labium (which may extend out a distance equal to about one-third of the insect’s length) is used to capture prey during the damselfly’s larval stage.
The thorax of the larval damselfly has three gills. Some species have oversized gills that function not only to absorb oxygen but also serve as paddles that help (along with undulating body motions), to propel the larval damselfly through water.
Some damselfly species in the larval stage are not swimmers, but instead crawl along the river bottom. A few native damselfly species are not aquatic at all, but instead are terrestrial during the larval stage.
Noted for its large size and red color, the Blackburn’s Hawaiian damselfly (M. blackburni) is the largest native Hawaiian damselfly species, with a wingspan that may exceed 2¾ inches (7 cm) and a length of up to 2-2/5 inches (6 cm).
The Hawaiian Upland damselfly (M. hawaiiense) is the native Hawaiian damselfly most likely to be encountered by humans, while the Scarlet Kaua‘i damselfly (M. vagabundum) is one of the most commonly encountered species on Kaua‘i.
Various fish species prey on damselflies, and new introductions of freshwater fish threaten native damselfly species. Wildlife officials are considering breeding endangered damselfly species on federal lands in order to restore their populations.
Blackburn’s Hawaiian damselfly (Megalagrion blackburni);
Hawaiian Upland damselfly (Megalagrion hawaiiense);
Scarlet Kaua‘i damselfly (Megalagrion. vagabundum)]
There are four endemic Hawaiian dragonfly species, including the Green Darner (Anax junius) and its close relative, the Giant Aeshnid dragonfly (Anax strenuus). The Giant Aeshnid is darker in color than the Green Darner, and also has a larger wingspan.
The Giant Aeshnid’s wingspan may be up to 6 inches (15 cm) long, making it the largest of all of native Hawaiian insects. The Giant Aeshnid is also larger than any dragonflies of the continental United States.
The other two native Hawaiian dragonflies are the Globe Skimmer (Pantala flavescens) and the Hawaiian Skimmer (Nesogonia blackburni).
[Photographs: Giant Aeshnid dragonfly (Anax strenuus);
Green Darner (Anax junius)]
A Comparison of Damselflies and Dragonflies
Damselflies and dragonflies are native Hawaiian water insects, along with numerous species of water beetles, craneflies, brineflies, and others. Damselflies and dragonflies are both members of the insect order Odonata.
The fossil record reveals that dragonflies evolved about 200 million years ago, and damselflies about 60 million years later. Damselflies are a bit smaller and more delicate looking than dragonflies. Both pairs of wings on damselflies are the same size, but the dragonfly’s front wings are larger.
The head of the dragonfly is rounder than the more rectangular-shaped head of the damselfly, and the damselfly’s eyes are separate while the dragonfly’s eyes are joined.
One easy way to tell dragonflies and damselflies apart is to watch them land and look at their wings when they are at rest. If the wings are folded vertically (closed above the body, pointing upward and back) then it is a damselfly, but if the wings at rest are horizontal (open in flight position, like the wings of an airplane), then it is a dragonfly.
In flight, dragonflies are more animated and powerful (faster) than damselflies. Damselflies generally spend less time flying than dragonflies.
Dragonflies usually feed on airborne insects and will often hover over their victims before attacking and capturing the prey. Damselflies alight on vegetation and then use their spiny front legs to capture their prey, which includes both flying and stationary insects.
Common habitats for both damselflies and dragonflies are ponds, waterfalls, pools in mountain streams, reservoirs, lo‘i kalo (taro patches), along beaches, and particular niches within Hawaiian rainforests.
Many damselfly species are very localized, and there is probably very little interisland dispersal. The dragonflies, however, have a strong dispersal capacity, traveling more widely than the damselfly. All four native dragonfly species are found throughout the Hawaiian Islands.
[Photograph: Kamehameha butterfly / Blackburn’s little blue butterfly]
[Text beneath photograph:]
The Kamehameha butterfly (Vanessa tameamea) is a native monarch whose Hawaiian name, lepelepe-o-Hina, means “to flutter here and there.” The Kamehameha butterfly’s color is a deep red/orange, lined with black. The caterpillars of the species feed on the leaves of māmaki (Pipturus species) and other native nettle plants.
The only other native Hawaiian butterfly is known as Blackburn’s little blue butterfly (Udara blackburni). Its wings have iridescent green scales on the underside, and bluish-brown scales on top. The species’ larvae feed on koa (Acacia koa) and ‘a‘ali‘i (Dodonaea viscosa).
Hawaiian Happyface Spider (Theridion grallator)
[Photograph: Happyface spider]
[Text beneath photograph:]
The Happyface spider is about ½-inch (13 mm) long. On the spider’s abdomen is an array of black and red marks that form a smile on its yellow body.
The Happyface spider feeds by hiding beneath leaves until it sees its prey’s silhouette on the leaf’s upper surface. The spider then reaches around and snatches its victim.
The Hawaiian Happyface spider has no known Hawaiian name, though the Hawaiian word for all spiders is lanalana.
Hawaiian Cave Species
[Illustration: Cave Spider]
In hollow underground caverns where molten earth once flowed, there lives an array of specialized cave creatures, many of which are blind and colorless.
To survive in this subterranean underworld of perpetual darkness, the cave creatures forage on the roots of trees, grasses and ferns that have probed their way down through the cave ceiling. They also prey on each other—the blind chasing the blind in the dark.
[Illustration: Cave scene.]
There are about 100 different native Hawaiian cave species, and at least 30 of these species exist nowhere else on Earth—they are endemic to the Hawaiian Islands. Hawaiian cave species include cave moths, tiny blind water treaders, eyeless planthoppers, blind wingless crickets, millipedes, centipedes, and many others.
Many caves in the Hawaiian Islands are actually lava tubes that formed when pāhoehoe lava flowing underground drained away and left a cave. Some Hawaiian lava tubes have more than 6 miles (9.6 km) of underground passages. The temperatures in the caves may be as low as 41° Fahrenheit (5° C).
Many Hawaiian cave fauna are strange, pigmentless species. Various adaptations allow cave insects to survive in their subterranean habitat. In the Thurston Lava tube (Hawaiian name: Nahukū) on the island of Hawai‘i’s Kīlauea Volcano (see Kīlauea Volcano in Hawai‘i Island section, Chapter 2), blind and mute tree crickets scavenge on organic matter and graze on young roots.
Wolf Spiders and Amphipods
The top predators in Hawaiian caves are long-legged runners called wolf spiders. Some Hawaiian wolf spiders are totally blind, yet they are not web weavers but hunters, chasing and grabbing their prey on open ground. The spiders locate and track their prey using their front legs, which are specialized for sensing sound waves.
One endemic cave spider species that uses this acoustic hunting is the rare and endangered[ii] pe‘e pe‘e maka (Adelocosa anops, no-eyed, big-eyed hunting spider).
With a leg span of about 1½ inches (4 cm), this sightless spider lays about 15-30 eggs in a clutch (group of eggs). The female spider carries the eggs in her mouth until they hatch, and then she carries the newly hatched spiderlings on her back for the first few days.
The principal prey of the Kaua‘i cave wolf spider is believed to be the Kaua‘i cave amphipod, a pale, shrimp-like landhopper that is also blind, and is related to crabs and sand fleas.
The Kaua‘i cave amphipod, a tiny crustacean, is only about ¼-inch (6 mm) long and feeds on old woody matter that works its way down through the rock from above and then begins to decay in the cave environment.
Only five populations of the Kaua‘i cave amphipod and three populations of the Kaua‘i cave wolf spider are known to exist. Other species of wolf spiders may be found on the island of Hawai‘i.
In June of 2000, the Kaua‘i cave wolf spider and Kaua‘i cave amphipod were listed as endangered by the U.S. Fish and Wildlife Service. The two endangered cave species exist in a predator-prey relationship, and are found only in a few moist lava tubes beneath southeastern Kaua‘i’s Kōloa lava flows.
[i] p. 9, Pukui, Mary Kawena. ‘Ōlelo No‘eau: Hawaiian Proverbs & Poetical Sayings. Honolulu: Bishop Museum Press, Proverb 62.
[ii] Hawaiian Cave Animals: Threatened and Endangered Species; Endangered Animals in the Hawaiian Islands. U.S. Fish and Wildlife Service. Internet site: http://www.r1.fws.gov/pacific/wesa/caveanimals.html, 6/17/2000.