Tag: hawaii

Island Weirdness #43 — Flightless Flies

One of the most defining features of the true flies is a pair of wings, but various different lineages have actually become flightless.

Flightlessness is very rare in the long-legged fly family (Dolichopodidae), however, with only about 12 out of over 5000 species known to have lost functional wings — and eight of those are endemic to the Hawaiian islands.

The Koʻolau spurwing long-legged fly (Emperoptera mirabilis, sometimes classified as Campsicnemus mirabilis) was found only on Mount Tantalus in the southern Koʻolau Range of Oʻahu, close to Honolulu. About 2mm long (>0.1″), its wings were reduced to thin stiff spines, and it moved around by walking and hopping in leaf litter in the moist cool forest at elevations of about 300m (~1000ft).

Like most other long-legged flies it would have been predatory, hunting other tiny invertebrates.

The Koʻolau spurwing was actually still common on Tantalus as recently as the early 1900s, but multiple searches since the 1980s have failed to find any more of them at all. The species is most likely completely extinct, probably due to a combination of predation from invasive ants and habitat destruction from feral wild boar rooting up the forest floor.

Of the other flightless Hawaiian long-legged flies several other species are now possibly extinct — only one out of the five known Emperoptera species still definitely survives on the highest slopes of Mount Kaʻala, and one of the three Campsicnemus is either very rare or also extinct.

The Hawaiian islands also have three endemic species of flightless crane fly in the genus Dicranomyia, all of which are incredibly rare.

Island Weirdness #42 — Tall Owls & Short Ibises

The complete lack of land mammals on the Hawaiian islands left the terrestrial predator niches available to birds — and it was owls who ended up taking advantage of that role in the ecosystem.

The Grallistrix owls were found on Kauaʻi, Oʻahu, Molokaʻi, and Maui, with each island having its own endemic species. They were a type of true owl, probably descended from a species of Strix, and developed especially long legs that led to their nickname of “stilt-owls”.

A stylized illustration of an extinct owl. It has short wings and very long stilt-like legs.
Grallistrix geleches

The Molokaʻi stilt-owl (Grallistrix geleches) was the largest of the four known species, about 60cm tall (2′). Although it had proportionally short wings it was still capable of flying, and probably specialized in stalking and ambushing smaller birds like Hawaiian honeycreepers in the dense forests.

(These owls were also the inspiration for the pokémon Decidueye!)

A stylized illustration of an extinct flightless ibis. It has a downward-curving beak, small wings, and relatively short thick legs compared to other ibises.
Apteribis glenos

Meanwhile the forest floor insectivore niche was occupied by Talpanas on Kauaʻi, but on the other main islands a different type of bird took up the same role.

Apteribis was an ibis closely related to the modern white ibis and scarlet ibis, with three different species found on the islands of Maui, Molokaʻi, and Lānaʻi.

The Moloka’i flightless ibis (Apteribis glenos) was a typical example of the genus, about 50cm long (1’8″). It was flightless, with reduced wings, and had unusually short stocky legs that gave it proportions much more like a kiwi than an ibis. And it probably lived very much like a kiwi, too, probing around in the forest litter with its beak searching for snails and other invertebrates.

We even have an idea of the coloration of these birds, thanks to subfossil remains with preserved feathers. They seem to have been brown and beige, similar to the juvenile plumage of their close relatives.

The arrival of humans at least 1000 years ago would have unfortunately been devastating to both the stilt-owls and the flightless ibises. The combination of hunting, habitat destruction, and invasive dogs, pigs, and rats attacking them and their ground-based nests probably drove them all into extinction very quickly.

Island Weirdness #41 — Talpanas lippa

The big herbivorous moa-nalo weren’t the only unusual waterfowl on the ancient Hawaiian islands — and the island of Kauaʻi had a very odd duck indeed.

The Kauaʻi mole duck (Talpanas lippa) was fairly small, about 50cm long (1’8″), and although it lived alongside one of the moa-nalo species they don’t seem to have been closely related at all. It instead appears to have come from a different duck lineage entirely, with it’s closest living relatives potentially being the stiff-tailed ducks.

It had short chunky legs and an especially weird skull, with eyes so tiny and underdeveloped that it must have been near-blind and flightless. But the areas of its brain associated with the sense of touch were proportionally huge, and although the exact shape of its beak currently isn’t known it seems to have been very wide and flat.

It was probably a nocturnal bird that used an incredibly sensitive bill to grub around in the undergrowth for invertebrates, sort of an equivalent of the modern kiwi but with a face more like a platypus.

The only known Talpanas remains come from mid-Holocene deposits about 6000 years old, but since Kauaʻi is the geologically oldest of the main Hawaiian islands it may have existed there for several million years prior.

Like the moa-nalo it was likely driven to extinction due to human influences on its environment once Polynesian settlers reached the island, sometime between 300 CE and 1200 CE.

Island Weirdness #40 — Moa-Nalo

The islands of Hawaii are part of a larger archipelago formed via hotspot volcanism in the Pacific, and are quite geologically young — the oldest of the main islands was formed just slightly over 5 million years ago, and the youngest less than 0.5 million years ago.

Located almost 3700km (2300 miles) from the nearest continental shore, they’re the most isolated islands on Earth. Their native species are all descended from the rare colonization events that reached such a remote location, either via ocean rafting or island hopping from much older now-submerged islands northwest in the chain.

Like many other Pacific islands no land mammals ever reached Hawaii prior to human arrival, and so it was birds that ended up filling many of the vacant ecological niches.

The dominant herbivores of most the islands were the moa-nalo — no relation to the moa of New Zealand — a group of large flightless birds that resembled giant geese but were actually descended from ducks, with their closest living relative thought to be the modern Pacific black duck. They had reduced wings, chunky legs, and big heavy beaks, some featuring large serrations and others convergently resembling those of giant tortoises.

The Maui Nui large-billed moa-nalo (Thambetochen chauliodous) was one of the biggest species, about 90cm tall (~3′). It originally lived in the highlands of Maui Nui, a large island that formed over 1 million years ago — and when Maui Nui subsided and flooded about 200,000 years ago, it would have then occupied the resulting modern islands of Maui, Molokaʻi, Lānaʻi, and Kahoʻolawe.

Polynesians reached the Hawaiian islands sometime between 300 CE and 1200 CE (the exact dating seems to be controversial). The moa-nalo would have suffered the same fate as many other flightless island birds, lacking any instinctive fear of the new arrivals and falling prey to the invasive pigs, dogs, and rats they brought with them.