Hawaiian Birds and Nihoa Millerbird Success
Endangered Nihoa Millerbirds were reintroduced to Laysan Island in 2011, after a 100-year absence, and are now breeding there. These tiny Hawaiian songbirds were relocated in a bold effort to initiate a second population and minimize the risk of extinction. Biologists monitoring the birds have just reported that some of the birds have laid eggs, and some of these eggs have now hatched.
The Nihoa Millerbird (Acrocephalus familiaris kingi) made an unsuccessful out-of-season breeding attempt shortly after their arrival. Now the birds are entering their first proper breeding season, and nest building activity was observed in February, and the first eggs in March. This first-ever opportunity to observe Millerbird breeding from start to finish and collect behavioral and life-history data throughout the season is a significant advance in the study of this endangered species. The next important milestone for Millerbirds on Laysan will be when chicks fledge and forage on their own. Following that, the project team will be looking for this first generation of Laysan-hatched birds to begin breeding themselves.
The first Millerbird translocation to Laysan Island, which is within Hawaiian Islands National Wildlife Refuge and the Papahanaumokuakea Marine National Monument, was the result of many years of research and detailed planning by biologists and resource managers. By creating a second population of Millerbirds on a second, distant island, the translocation project will reduce the chances that catastrophic events on Nihoa, such as hurricanes or the introduction of predators, will drive the Millerbird to extinction. Plans are already underway for a second translocation to ensure that the Laysan population has a solid foundation to build upon.
Hawaiian Birds and Bryan’s Shearwater
After decades of research, scientists have confirmed thru DNA a unique specimen among the other known species of Shearwaters. Most of the more than 9,000 known bird species, including twenty-one Read more
Hawaiian Birds and Short-tailed Albatross Success 2
An endangered Short-tailed Albatross has nested in the United States and produced a chick for the second time ever recorded. The recent discovery of the nest and chick on Midway Atoll in the Northwestern Hawaiian Islands follows the fledging of the first U.S.-born chick last year at the same site by the same parents. This news suggests that the first chick hatched last year was not an isolated incident, and this may be the early stages of the formation of a new population of this very rare bird.
The Short-tailed Albatross (Phoebastria albatrus) was once the most abundant albatross species of the North Pacific, numbering more than a million birds. Feather hunters decimated the population around the turn of the century, however, and researchers believed by the 1940’s that the species had gone extinct. In the early 1950s, ten pairs were discovered breeding on the volcanic island of Torishima, Japan, and they have grown to 3,000 individuals.
Midway Atoll is home to the world’s largest colonies of Laysan and Black-footed albatrosses, as well as millions of other seabirds. 55 miles from Midway, another Short-tailed Albatross pair is attempting breeding on Kure Atoll, the northern-most coral atoll in the world. Both Midway and Kure are part of the Papahānaumokuākea Marine National Monument. Albatrosses tend to be faithful to the place of their birth, returning when they are around 8 years old to rear their own young. So it will be several years before researchers find out whether or not a full-fledged short-tailed American colony is in the making.
Hawaiian Birds and Hawaiian Honeycreepers
Smithsonian scientists have determined the evolutionary family tree for one of the most strikingly diverse and endangered bird families in the world – the Hawaiian Honeycreepers. The researchers determined the types of finches that the honeycreeper family originally evolved from and also linked the timing of that rapid evolution to the formation of the main Hawaiian Islands. Using genetic data from 28 bird species that seemed similar to the honeycreepers morphologically, genetically or that shared geographic proximity, it was determined that the various honeycreeper species evolved from Eurasian rosefinches.
There were once more than 55 species of these colorful songbirds, and they are so diverse that historically it wasn’t even entirely clear that they were all part of the same group. Honeycreepers probably represent the most impressive example of an adaptive radiation in vertebrates that has led to a number of beak shapes unique among birds. Some eat seeds, some eat fruit, some eat snails, some eat nectar. Some have the bills of parrots, others of warblers, while some are finch-like and others have straight, thin bills.
Hawaii’s unusual geology played a role in the rapid evolution of many honeycreeper species that followed. The volcanic islands have formed one by one over time, as the Pacific tectonic plate is dragged across a “hot spot” of magma, and each new island provided a new opportunity for colonization. Each island that forms represents a blank slate for evolution, so as one honeycreeper species moves from one island to a new island, those birds encounter new habitat and ecological niches that may force them to adapt and branch off into distinct species.
The researchers looked at the evolution of the Hawaiian honeycreepers after the formation of Kauai-Niihau, Oahu, Maui-Nui and Hawaii. The largest burst of evolution into new species, called a radiation, occurred between 4 million and 2.5 million years ago, after Kauai-Niihau and Oahu formed but before the remaining two large islands existed, and resulted in the evolution of six of 10 distinct groups of species characterized by different sizes, shapes and colors.
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.
