Hawaiian Birds and Nihoa Millerbird Conservation
The Nihoa Millerbird was originally confined entirely to Nihoa Island in Hawaiian Archipelago. Nihoa Millerbird is resident only on this uninhabited island refuge. Before its extinction, the Laysan Millerbird was resident only on Laysan Island. Their extinction between 1916 and 1923, was caused by human introduction of rabbits which destroyed the Millerbird’s habitat. Before vegetation was destroyed by rabbits on Laysan Island, the now extinct Laysan Millerbird was one of the most abundant of the 5 endemic birds. The Laysan Millerbird, Laysan Honeycreeper, and Laysan Rail are now extinct. The other 2 endemic birds still present are the Laysan Duck (Anas laysanensis) and Laysan Finch (Telespiza cantans).
When Nihoa Millerbirds were first discovered in 1923, the population was estimated to be 100 birds. The population size of the Nihoa Millerbird (Acrocephalus familiaris kingi) has fluctuated between 30 and 700 birds in the last 30 years, and the 2009 population estimate was 640. Threats include small population size, weather (drought, storms, hurricanes), variations in insect food supply, limited available habitat and nesting territories on the small island, introduced plants, animals, and fire. All these threats are very serious as this is the only place in the world where these birds can be found.
The Nihoa millerbird was listed as an endangered species in 1967 under the Federal Endangered Species Act. Nihoa is part of the Hawaiian Islands National Wildlife Refuge created in 1909 and the Papahānaumokuākea Marine National Monument, and access is restricted due to the island’s fragile ecosystem. For many years biologists have been considering the translocation of sufficient millerbirds to create a second population on another Hawaiian island to reduce the risk of extinction. Laysan Island is the first choice for this translocation effort, with a goal of doubling the population of this endangered bird through the translocation and creation of a second population on Laysan Island.
Hawaiian Birds and Nihoa Millerbird Breeding
The Nihoa Millerbird is only found on the Hawaiian Island of Nihoa in Papahanaumokuakea Marine National Monument. As name implies, Nihoa Millerbirds feed on all stages of Miller Moths. The main foods eaten also include other moths and caterpillars, insects, larvae, flies, grasshoppers, and small beetles. Nihoa Millerbirds frequently eat the bug Nysius, abundant on small shrub ‘aweoweo, flea beetles, numerous on popolo plants, and insects on ‘ilima bushes and the bunchgrass Eragrostis.
The Nihoa Millerbird (Acrocephalus familiaris kingi) has a metallic and bubbling voice. Male frequently sings, especially during breeding season. Their song has been described as thin, metallic, and energetic. However, songs of single-island endemics are usually rather simple and short, which is the case with Nihoa Millerbird. During breeding season, Nihoa Millerbirds sing loudly and continuously from tops of larger bushes, which are primarily ‘ilima, ‘aweoweo, and popolo. The female has a soft courtship vocalization.
Male singing is most frequent before and during initial nest construction and may erect crown and chin-feathers during bouts of singing or courtship feeding. Nesting may occur anytime between January and May, and takes less than two weeks. Both sexes of Nihoa Millerbird build nest. The male spends more time gathering material and the female brings less nest material but spends longer putting it into nest. Their cup nest is composed of dead grass fine rootlets, twigs, dried grass stems and blades, and down feathers. An average clutch contains two eggs. Both sexes generally alternate incubation, and chicks are fed directly by both parents.
Hawaiian Birds and Nihoa Millerbird
The Nihoa Millerbird is endemic to the remote island of Nihoa in Papahanaumokuakea Marine National Monument. This tiny bird measuring approximately five inches in length that was discovered in 1923 on this small island of only 155 acres, of which less than 100 are vegetated, and the rest being rock or bare soil. Another subspecies once occurred on Laysan Island, where it went extinct in the early 20th century after the island was de-vegetated by introduced rabbits. The Laysan Millerbird, discovered first, was given its name because of its fondness for feeding on large miller moths. The Laysan and Nihoa Millerbirds are generally regarded as separate subspecies.
The Nihoa Millerbird (Acrocephalus familiaris kingi) is a small reed-warbler, dark olive and olive brown above with grayish margins on feathers. They are whitish below with some grayish olive wash on sides and buffy brown flanks. The sexes are similar, with the females being slightly smaller. On the ground, they hop rather than run, and prefer dense cover near the ground, especially ‘aweoweo and ‘ilima.
Nihoa Island is steep and rocky, with steep cliffs on three of the island’s four sides rising out of the sea to 900 feet. Access to the Nihoa Millerbird is limited not only by the remoteness of Nihoa Island and required access permits, but also by the difficulty of landing on this steep, rocky island, often surrounded by rough seas. Although this endangered species has been somewhat protected by limited and difficult access, these restrictions also have limited research on its natural history. Research is also curtailed by justifiable concerns about the negative impact of even minimal human activities on the seabird colonies, as well as its numerous endemic plants and invertebrates. Millerbird population estimates since the 1960s have ranged from 31 to 731. Photo by Jack Jeffrey.
Hawaiian Birds and Puaiohi Nest Boxes
The Puaiohi, also known as the Small Kauaʻi Thrush, is endemic to a small part of the island of Kauaʻi and is listed under the Endangered Species Act as Endangered. Puaiohi nest in natural cliff and tree cavities, and like many other native Hawaiian bird species, is highly vulnerable to predation by rats, which prey on eggs, chicks, and even adults. Pigs also destroy native forest understory vegetation where Puaiohi spend much of their time. Non-native plants make their habitat unsuitable, in some cases overwhelming their nesting sites on cliffs and along stream banks with vegetation.
But, there is renewed hope for conservation of the endangered Puaiohi (Myadestes palmeri). The Zoological Society of San Diego has bred and released nearly 200 Puaiohi into the wild since 1999, which has helped maintain the wild population. The Kauai Forest Bird Recovery Project has also placed nest boxes along the Kawaikoi Stream located in the Na Pali-Kona Forest Reserve and the Halepaʻakai Stream in the Alakaʻi Wilderness Preserve, which provide nest sites that are safer from rats, and further bolstering prospects for the species’ recovery.
Nest boxes put up in 2007 by the Kauaʻi Forest Bird Recovery Project have recently resulted in the fledging of a chick. This event is only the second time ever that Puaiohi chicks have fledged from nest boxes in the wild. Furthermore, during checks at the end of the season, fresh nest material was found in three other nest boxes, indicating that Puaiohi have been actively exploring and perhaps using even more nest boxes. When there are only approximately 500 mature individuals of a species left, small successes such as this are reasons to be excited. Photo by Eric VanderWerf.
Hawaiian Bird Photographer Jack Jeffrey
Jack Jeffrey has been studying and photographing Hawaii’s endemic birds for over thirty years. As a long time resident of the Big Island, a wildlife biologist, and a photographer, Jack Jeffrey, is intimately familiar with Hawaii’s hidden valleys, remote rain forests and rare birds. He combines a naturalist’s curiosity with a photographer’s patience and technical skill to produce beautiful images. Photographing Hawaii’s native forest birds in the wild is no easy matter. For some species, with very small populations, seeing the bird is next to impossible, never mind trying photographing it.
Publications that have featured his work include: Audubon Magazine, Smithsonian, Life, Natural History, Birders World, National Wildlife, Pacific Discovery, Defenders of Wildlife, Science, National Park, the National Geographic Canon Endangered Species Series, as well as numerous books, and calendars.
“Many of Hawaii’s birds are on the brink of extinction. I’d hate to think that I’m only recording images of these magnificent creatures for posterity. I’d rather believe that through my photography, I am providing an emotional link between humanity and the birds. If I do what I love… my passion…I feel that I’m doing my best to ensure that Hawaii’s people, and visitors from around the world, will continue to have opportunities to enjoy these colorful forest treasures for many generations to come.”
Hawaiian Birds and ‘O’u Conservation
The ‘O’u is a Hawaiian Honeycreeper that has been federally listed as endangered since 1967. With the last published sighting on Kauai in 1989, it is now quite possibly extinct. Distribution has been shrinking since 1900s, disappearing from Oahu by 1899, Maui by 1901, Molokai by 1907, and Lanai by 1931. On Kauai and Hawaii, ‘O’u (Psittirostra psittacea) are thought to persist in a fraction of its former range. Their range has contracted from low-elevation habitat since the first specimens were collected near sea level in 1779. The most recent range estimate is high elevation forests on windward Hawaii and in the Alaka‘i Swamp on Kauai.
Hurricanes such as ‘Iwa (1982) and ‘Iniki (1992), which struck Kauai, can eliminate all fruit and foliage in certain areas, causing widespread starvation or movement to lower elevations, thus resulting in exposure to avian disease. Introduced avian diseases are widely considered one of foremost causes of forest bird extinction in Hawaiian Islands. Introduced mosquitoes transmit avian malaria that is limiting populations of low-elevation native birds.
Feral house cats and rats are known to depredate ‘O’u and other Hawaiian forest bird populations through nest predation. Birds that may have preyed on ‘O’u include a bird-eating owl (Grallistrix auceps), the Hawaiian Hawk (Buteo solitarius), Short-eared Owl (Asio flammeus sandwichensis) and the introduced Barn Owl (Tyto alba).
