Hawaii is home to a variety of unique species including many endemic birds, birds that are found nowhere else in the world besides these islands. One such bird is the Iiwi, a brilliant red bird with a deeply curved beak, one of the 17 species of honeycreepers that can be seen.
The iiwi belong to the family Fringillidae. This family contains 235 species including finches, grosbeaks, Euphonias, redpolls, crossbills and many others. One of their closest relatives is the Apapane, both of which belong to the subfamily Carduelinae, which also contains the American Goldfinch. Like others in their family, they have an undulating flight pattern, with a few quick wing beats upward, then a quick drop down with closed wings, repeated over and over til they get to their next perch.
The iiwi’s scientific name is Drepanis coccinea. This small songbird is mostly a brilliant vermillion with contrasting black wings and tail. Their wings also have a white patch on their inner secondaries. Their orange bill is long and downward-curved and their long seemingly oversized legs are also orange. Their dark brown eyes are ringed by a faint yellow ring. Measuring in at about 15 centimeter long and weighing about 16-20 g, about the same as a four nickels. Like most songbirds, the males are slightly larger than the females. As this species main diet is nectar, they have a tubular tongue with brushy tip. During the breeding season they stay in pairs, other times of the year they can be seen in small flocks of two to nine individuals.
Their preferred habitat tends to be wet forests above 1,500 meters in elevation. They can be found mostly on the islands of Hawai’i, Maui and Kaua’i, and to a lesser extent on O’ahu and Moloka’i, which are believed to each only have about 50 individuals left and they are extinct on the island of Läna’i.
Like other honeycreepers, they are a nectar specialist, their long downward curved beak is specially adapted to reach the nectar in tubular flowers such as mints, lobelias, and the ōhi’a tree. They are a very active forager, going quickly from flower to flower, sometimes hanging upside down to access them, often visiting a dozen different flowers in a few minutes. To obtain nectar they sometimes will pierce a flower at its base to access it. Also included in their diet is a variety of spiders and insects, including butterflies, moths, hoppers, lacewings, flies, bees and wasps.
Throughout the year, they will typically travel up and down the mountains, following the blooming flowers, especially those of the öhi‘a tree. They can be fiercely territorial of their territory and defend their flowering trees and plants from other birds. As a nectarivore, they are an important pollinator for many plant species.
Their vocalizations include their song and calls and a nonvocal soft whirring sound produced by their primaries in flight. Calls can be loud and squeaky, more like a clear whistle, or flutelike. Their song is often referenced to the sound of balloons rubbing together or a squeaking door hinge. Both males and females will sing throughout the year, but it is more common in October through December, which is the beginning of their breeding season.
The iiwi are monogamous and typically breed from February to June. The nest is built by both the male and female, with ferns, lichens, plant fibers and twigs, formed into a cup shaped nest that is about 9.5 centimeters across and 7.4 centimeters deep. These nests are usually constructed high up in trees, in a terminal branch. Inside this nest, usually two 2cm long oval eggs which are whitish with dark brown speckles, spots or blotches on them will be laid, which will then hatch in about 14 days. The iiwi is altricial, hatching with its eyes closed, orange-pink skin with dirty white or gray down and a straight bill. After about six days, their bill will start to curve. After 21-24 days from hatching, they will officially fledge the nest. The young iiwi at this point do not look quite like their parents, juveniles are more mottled, with plumage being a dull yellow-ish brown with black spots and have a brown bill. They will still be dependent on their parents for about 4 months.
While the I’iwi was once the most common forest bird found in Hawaii, they are now classified as vulnerable. One of the many threats facing this species, along with many forest birds on Hawaii, is from an unexpected pest, the mosquito. These mosquitoes carry bacteria and viruses that these native hawaiian species have never been exposed to and have no immunity too. These ailments can include avian pox and malaria. Studies have even shown that approximately 90% of birds bitten by a mosquito carrying malaria will die from the disease.
Generally these mosquitos can only live in particular temperatures, preventing them from moving up the mountains and predominantly staying in lowland areas, unfortunately due to climate change, temperatures high up in altitude are getting warmer, allowing these insects to climb high up the mountains, putting more and more birds at risk. The individuals that stay higher up in the mountains are for the time, safe from this disease but if they go lower, which they do often as they follow where the flowers are blooming, they enter areas where mosquitoes can be, they then become at risk of contracting this deadly disease.
Habitat loss is also a threat that these birds are unfortunately very familiar with, loss from human developments and agriculture, and on top of that, loss from forests being overgrazed by feral pigs, sheep and goats. It is estimated that they have lost approximately 52% of their former habitat on Hawai’i and 85% on O’ahu.
On top of these two major factors these native forest birds are also facing threats from introduced mammals, such as cats, rats, and mongooses. These predators aren’t only just a threat to adults, but will also raid nests of eggs and chicks.
There is hope though, with several organizations teeming up advocating for solutions to the threats facing Hawaii’s native wildlife, whether that be from the mosquitoes, invasive species, both plants and animals all the while encouraging people to live harmoniously with the wildlife around them. Hopefully these downward declines that many of hawaii’s birds are facing can be revered and the iiwi can one again be one of hawaii’s most common forest birds.