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 Birds and Puaiohi Success
The Hawaii Endangered Bird Conservation Program released 12 captive-bred Puaiohi (Kauai thrush) into the Alakai Wilderness Area of Kauai. This was the program’s 13th release in 12 years, and brings the total number of captive-bred Puaiohi released to 200. The Puaiohi (Myadestes palmeri) is found only on the Hawaiian island of Kauai, and is now restricted to habitat within the Alakai Wilderness Area. Survey teams currently estimate the surviving population of wild puaiohi to be around 500 individuals, which is twice the population that was estimated in the late 1990s.
Following each captive-breeding season they decide which puaiohi to release and which to keep, based on genetics and demography. After they are selected, each bird receives a physical examination and blood screening to ensure proper health and fitness for survival in the wild. It is thought that younger birds are less likely to be chased off by resident adults, as their juvenile plumage displays them as non-threatening in established territories. Additionally, young birds have young minds, which are thought to be more flexible in adapting to their new habitat and wild food sources.
Upon arrival on Kauai, the puaiohi were transported to the release site, where they settled into their acclimatization aviaries. Over the next week the birds experienced the new sights and sounds of the surrounding Kauai forest, sampled some of the local food (native berries such as lapalapa and pilo), and grew accustomed to the Alakai weather. Then, the 12 eager Puaiohi were released and excitedly “attacked” the surrounding plant and invertebrate populations, foraging on juicy berries and scavenging through tree bark and moss clumps for tasty insects. Most of the birds left the area to explore other parts of the Alakai, although two birds remained faithful to the area around the release.
Hawaiian Birds and Puaiohi Conservation
The Puaiohi is an elusive bird found only on the island of Kaua’i, where it makes its home in the high elevation forests of the Alaka’i Wilderness Preserve. Although currently critically endangered, Puaiohis (Myadestes palmeri) have the potential to become one of the true conservation success stories of the Hawaiian Islands. These small thrushes have an extended breeding season in their stronghold of the Alaka’i Swamp, renesting quickly after both successful and failed nesting attempts. This high reproductive potential has allowed conservationists to establish a captive population of these birds, and then reintroduce them into suitable unoccupied habitat. In 1999, a pair of released birds successfully hatched two chicks, marking a significant milestone in Hawaiian conservation efforts, and raising hopes that Puaiohis will be able to significantly increase their numbers and their range, and lead toward the recovery of a species.
Puaiohis were listed as Endangered in 1967. In 1994, it was estimated that less than 200 puaiohi survived in the wild. In 1995, a breeding population of Puaiohis was discovered, spurring a research and management program focused on two strategies: protecting nests and fledglings from rats by using rat-poison bait stations, and removing first-clutch eggs from nests to create a captive flock (removed clutches are quickly replaced by a new clutch in the wild).
To help the species recover, eggs were taken from the Alaka’i Wilderness Preserve to the Keauhou Bird Conservation Center on Maui, where they could be raised in a protected environment. To date, one hundred eighty-eight of these endangered birds have been bred in captivity and released annually into the forests of Kaua’i over the last 10 years. Prior to release, each Puaiohi is banded for identification and fitted with a radio transmitter. The birds are monitored for 30 days (the lifespan of the batteries) to watch the birds’ movements and determine their survival rate. This milestone in the conservation of native Hawaiian birds is one strategy to ensure that the puaiohi does not go extinct.
At least 21 species of Hawaii’s endemic forest birds have become extinct, and another 26 species are facing extinction. The state-of-the-art Keauhou Bird Conservation Center is also working on projects to see if puaiohi will use rat-proof structures for nesting. The preservation and management of what remains of their native forest habitat is vital if this rich and colorful part of Hawaii’s natural heritage is to endure.
Hawaiian Birds and Puaiohi Breeding
Puaiohi are found only in the Alaka‘i Swamp of Kaua‘i, with seventy-five percent of the breeding occurring in only 5 square miles of forest. So inaccessible and remote is the Puaiohi (Myadestes palmeri) habitat that it wasn’t until 1981 when the first nest was discovered. This small secretive thrush builds their nests in cavities of cliff faces, on ledges of streams, or in trees. The nests are usually made of (or concealed by) mosses, ferns, and grasses.
Females are the sole nest builders, which can take up to 7 days. She also incubates the eggs, and broods and feeds the young birds while still in the nest. Their eggs (usually 2) are colored grayish-green to a muted greenish-blue with irregular reddish-brown splotches, and hatch after 13 to 15 days. After fledging, the males become primary food providers to the young, while the female attempts a second brood. Outside the breeding season most of the diet is fruit and berries, while during the breeding season over fifty percent of the diet shifts to invertebrates. Puaiohis have an extended breeding season from March to September, and will renest quickly after successful or failed nesting attempts.
Song is given by males primarily in courtship and territory maintenance. It is a simple reedy song that usually consists of a preparatory whistle and a prolonged trill, followed by several sharp descending notes. It has been described as wheezy and highpitched, like the squeaking of a metal wheel in need of lubrication. The female has an expansive repertoire, including whisper calls, whisper song, alarm call, growl, and other unique vocalizations when intruder approaches fledgling or nest.
The typical call is a simple, dry, raspy hiss. The Alarm Call is a modification and much raspier, drawn out, and given every few seconds while the threat persists. Adults also may utter a Growl Call which is a short, low-pitched, throaty, but lacking its hissing quality. Once heard, this unique call is not likely to be confused with that of any other species. Photo by Jack Jeffrey
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Hawaiian Birds and Puaiohi
The Puaiohi (Small Kauaʻi Thrush) is a rare species of songbird that is endemic to the Hawaiian island of Kauaʻi. It is closely related to the other four endemic Hawaiian thrushes, the Kāmaʻo, Olomaʻo, ʻŌmaʻo, and ʻĀmaui. The plumage is dark brown above, with gray-brown upperparts, and a light gray breast below. They have a slender black bill and pinkish feet. A white eye ring is also fairly prominent, and along with white outer tail feathers helps distinguish this bird from the other Hawaiian thrushes. Both males and females are highly similar in appearance, and no more than seven inches in length.
The song is varied, consisting of a simple till to a complex wheezing, and high pitched squeal or squeaking resembling a metal wheel needing lubrication. Males can be found singing throughout the year, and with increasing frequency as breeding season approaches, peaking in April and May.
Puaiohis (Myadestes palmeri) are primarily fruit-eating birds, with the most frequently consumed fruits being ‘olapa, lapalapa, and ‘ohi’a ha. During the non-breeding season, most of their foraging is on fruits, while during breeding season, the percentage of invertebrates including dragonflies, beetles, spiders, and caterpillars becomes much higher.
This species has always been considered rare, favoring forested ravines above 3,400 feet in the center and southern parts of the Alakaʻi Wilderness Preserve. Their entire range, which includes stream valleys and ridges in the Alaka’i area, is now less than 10 square miles. It was added to the United States Federal Endangered Species list in 1967, and population estimates have dipped as low as 100 to 125 birds.
Photo by Jim Denny
