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At least 19 recordsLinked to original sources
USGS2019

Increased nesting success of Hawaii Elepaio in response to the removal of invasive black rats

In Hawaii and other oceanic islands with few native land mammals, black rats (Rattus rattus) are among the most damaging invasive vertebrate species to native forest bird populations and habitats, due to their arboreal behavior and generalist foraging habits and habitat use. We evaluated the nesting response of Hawaii Elepaio (Chasiempis sandwichensis; Monarchidae), a generalist insectivore, to the removal of black rats using rodenticide in a before-after-control-impact study in high- and low-elevation mesic montane habitat recovering from long-term damage from introduced ungulates and weeds. We monitored nesting success and rat abundance during 2015–2016 before applying rodenticide bait in 2017 to remove rats from two 700 × 700 m treatment plots that were paired with 2 nontreatment plots of the same size. Rat abundance was reduced by 90% during treatment, with combined variables treatment and elevation best explaining the change using GLM methods and AIC model selection. The daily survival rate (DSR) of nests (n = 191) was greater on treated plots after rodenticide application (mean ± SE = 0.980 ± 0.004 treatment; 0.964 ± 0.004 nontreatment), modeled nest success increased from 29% to 50%, and apparent nest success (number of successful nests per total nests) increased from 37% to 52%. The most informative model for predicting DSR included the effect of treatment. Predation by rats was documented at 3 of 16 nests using video surveillance, and we observed additional evidence of rat predation during in-person nest monitoring. Rats targeted adults on the nest and sometimes removed intact eggs, leaving little trace of their activity. Our results demonstrate that reducing rat predation can immediately improve the nesting success of even a common bird species in habitat with a long history of forest restoration. Sustained predator control may be critical to accelerating the recovery of native forest bird communities.

Hawaii↗
USGS2021

Current distribution and abundance of Kohala forest birds in Hawai‘i

The Kohala volcano is home to the most spatially isolated population of Hawaiian forest birds on Hawai‘i Island and contains one of the few native bird populations in the state that has not been monitored since the original Hawai‘i Forest Bird Survey (HFBS) in 1979. We surveyed 143 stations across 13 transects in Pu‘u ‘O ‘Umi Natural Area Reserve on Kohala from February through April 2017 and compared our results to data from the 1979 HFBS conducted at 80 stations across three transects in the same location as our study site. We detected 2806 individuals of 15 species and measured relative abundance, relative occurrence, and density for seven species. We observed changes in species densities ranging from −8.4% (Hawai‘i ‘Elepaio, Chasiempis sandwichensis ) to +714% (‘I‘iwi, Drepanis coccinea ). Equivalence testing showed meaningful increases in population densities for all but one species, the Hawai‘i ‘Elepaio. The increases in population densities on Kohala are in stark contrast to the widespread declines in population densities of native species elsewhere in Hawai‘i. Relative occurrence was greater in 2017 than in 1979 for all species except Hawai‘i ‘Elepaios and House Finches ( Haemorhous mexicanus ), and relative abundance increased for all species except Hawai‘i ‘Elepaios, House Finches, and Melodious Laughing Thrushes ( Garrulax canorus ). We also documented the range expansion of Japanese Bush Warblers ( Cettia diphone ) in Kohala. Our results indicate that this spatially isolated avian community remains biologically diverse, and most population densities are increasing in the study area. Our results provide a framework for future surveys and a baseline for understanding possible changes in population and community dynamics as birds respond to climate change and avian disease on Kohala volcano.

Hawai'i↗
USGS2007

Diversity, origins and virulence of Avipoxviruses in Hawaiian Forest Birds

We cultured avian pox (Avipoxvirus spp.) from lesions collected on Hawai'i, Maui, Moloka'i, and 'Oahu in the Hawaiian Islands from 15 native or non-native birds representing three avian orders. Phylogenetic analysis of a 538 bp fragment of the gene encoding the virus 4b core polypeptide revealed two distinct variant clusters, with sequences from chickens (fowlpox) forming a third distinct basal cluster. Pox isolates from one of these two clusters appear closely related to canarypox and other passerine pox viruses, while the second appears more specific to Hawai'i. There was no evidence that birds were infected simultaneously with multiple pox virus variants based on evaluation of multiples clones from four individuals. No obvious temporal or geographic associations were observed and strict host specificity was not apparent among the 4b-defined field isolates. We amplified a 116 bp 4b core protein gene fragment from an 'Elepaio (Chasiempis sandwichensis) collected in 1900 on Hawai'i Island that clustered closely with the second of the two variants, suggesting that this variant has been in Hawai'i for at least 100 years. The high variation detected between the three 4b clusters provides evidence for multiple, likely independent introductions, and does not support the hypothesis of infection of native species through introduction of infected fowl. Preliminary experimental infections in native Hawai'i 'Amakihi (Hemignathus virens) suggest that the 4b-defined variants may be biologically distinct, with one variant appearing more virulent. These pox viruses may interact with avian malaria (Plasmodium relictum), another introduced pathogen in Hawaiian forest bird populations, through modulation of host immune responses. ?? 2007 Springer Science+Business Media B.V.

Conservation Genetics↗
USGS2003

Evidence of change in a low-elevation forest bird community of Hawai'i since 1979

We evaluated the abundance and distribution of low-elevation forest birds on windward Hawai'i Island during August 1993-February 1994, and present evidence of changes in the species composition of the forest bird community since 1979. Endemic Hawaiian birds occurred in native-dominated forests as low as 120 m elevation. Non-native species were detected at all survey locations. We observed non-native Saffron Finch Sicalis flaveola , previously unrecorded in Puna. Variable circular plot surveys of Kahauale'a Natural Area Reserve indicated the disappearance of two native species ('I'iwi Vestiaria coccinea and 'O'u Psittitostra psittacea ), and two non-native additions (Red-billed Leiothrix Leiothrix lutea and Kalij Pheasant Lophura leucomelana ) to the study area since the Hawai'i Forest Bird Survey conducted in 1979. We present evidence that native 'Elepaio Chasiempsis sandwichensis has experienced a decrease in population density and an elevational range contraction since 1979. Surveys indicate Puna's forest bird community has had increasing aliens and declining native species since 1979. The persistence of some native bird species within the range of avian disease vectors such as Culex quinquefasciatus in forests below 1,000 m elevation presents an important enigma that requires additional study.

Hawai'i↗
USGS2014

Changing climate and the altitudinal range of avian malaria in the Hawaiian Islands: an ongoing conservation crisis on the island of Kaua'i

Transmission of avian malaria in the Hawaiian Islands varies across altitudinal gradients and is greatest at elevations below 1500 m where both temperature and moisture are favorable for the sole mosquito vector, Culex quinquefasciatus, and extrinsic sporogonic development of the parasite, Plasmodium relictum. Potential consequences of global warming on this system have been recognized for over a decade with concerns that increases in mean temperatures could lead to expansion of malaria into habitats where cool temperatures currently limit transmission to highly susceptible endemic forest birds. Recent declines in two endangered species on the island of Kaua'i, the ‘Akikiki (Oreomystis bairdi) and ‘Akeke'e (Loxops caeruleirostris), and retreat of more common native honeycreepers to the last remaining high elevation habitat on the Alaka'i Plateau suggest that predicted changes in disease transmission may be occurring. We compared prevalence of malarial infections in forest birds that were sampled at three locations on the Plateau during 1994–1997 and again during 2007–2013, and also evaluated changes in the occurrence of mosquito larvae in available aquatic habitats during the same time periods. Prevalence of infection increased significantly at the lower (1100 m, 10.3% to 28.2%), middle (1250 m, 8.4% to 12.2%), and upper ends of the Plateau (1350 m, 2.0% to 19.3%). A concurrent increase in detections of Culex larvae in aquatic habitats associated with stream margins indicates that populations of the vector are also increasing. These increases are at least in part due to local transmission because overall prevalence in Kaua'i ‘Elepaio (Chasiempis sclateri), a sedentary native species, has increased from 17.2% to 27.0%. Increasing mean air temperatures, declining precipitation, and changes in streamflow that have taken place over the past 20 years are creating environmental conditions throughout major portions of the Alaka'i Plateau that support increased transmission of avian malaria.

Hawai'i↗
USGS2007

Forest Bird Distribution, Density and Trends in the Ka'u Region of Hawai'i Island

An accurate and current measure of population status and trend is necessary for conservation and management efforts. Scott and Kepler (1985) provided a comprehensive review of the status of native Hawaiian birds based on the extensive Hawaii Forest Bird Survey (HFBS) of the main islands (Scott et al. 1986). At that time, they documented declining populations and decreasing ranges for most species, and the extinction of several species over the previous 50 years. Many native bird species continue to decline throughout Hawai`i (Camp et al. In review, Gorresen et al. In prep.). The focus of this study is the mid-to-high elevation rainforest on the southeast windward slopes of Mauna Loa Volcano (Figure 1). Known as Ka`u, the region encompasses forest lands protected by Kamehameha Schools, The Nature Conservancy, Hawai`i Volcanoes National Park (HVNP), and the State of Hawai'i's Ka`u Forest Reserve, Kapapala Forest Reserve and Kapapala Cooperative Game Management Area,. Together these lands support one of three main concentrations of native forest birds on the Hawai`i Island (the other two being centered on the Hakalau Forest National Wildlife Refuge and Kulani-Keauhou area in the north and central windward part of the island, respectively.) Because this region harbors important populations of native and endangered forest birds in some of the best remaining forest habitat on the island, it has been a focus of forest bird surveys since the 1970s. The Ka`u region was first quantitatively surveyed in 1976 by the Hawaii Forest Bird Survey (Scott et al. 1986). Surveys were conducted by State of Hawai`i Division of Forestry and Wildlife in 1993 and 2002 and by the U.S. National Park Service and the U.S. Geological Survey in 2004 and 2005. In this report, we present analyses of the density, distribution and trends of native and introduced forest bird within the Ka`u region of Hawai`i Island. The analyses cover only those species with sufficient detections to model detection probability and calculate density. These include three endangered native passerines: `Akiapola`au (Hemignathus munroi), Hawai`i Creeper (Oreomystis mana), and Hawai`i `Akepa (Loxops coccineus); five more common native passerines: the Hawai`i `Elepaio (Chasiempis sandwichensis), `Oma`o (Myadestes obscurus), Hawai`i `Amakihi (Hemignathus virens), `I`iwi (Vestiaria coccinea) and `Apapane (Himatione sanguinea); and three non-native species: Red-billed Leiothrix (Leiothrix lutea), Japanese White-eye (Zosterops japonicus), and Northern Cardinal (Cardinalis cardinalis).

Open-File Report↗
USGS2009

Passerine bird trends at Hakalau Forest National Wildlife Refuge, Hawai‘i

Hakalau Forest National Wildlife Refuge, on the Island of Hawai‘i, was established in 1985 to protect native forest birds, particularly endangered species. Management actions on the 15,400 ha refuge include removing feral ungulates from the forest and pastures, controlling invasive alien plants, reforesting pastures, and supplementing endangered plant populations. To assess effects of this habitat improvement for birds, we calculated annual density estimates from point transect surveys and examined population trends for eight native and four alien passerine bird species over the 21 years since the refuge was established (1987-2007). We examined trends using a Bayesian approach to log-linear regression. We tested for changes in bird density in three study areas: (1) a middle elevation forest that had been heavily grazed, (2) an upper elevation pasture that was reforested during the study, and (3) a lower area of relatively intact forest that was formerly lightly grazed. In the middle study area, we found that densities of Hawai‘i ‘Elepaio (Chasiempis s. sandwichensis), and the endangered ‘Akiapōlā‘au (Hemignathus munroi) and Hawai‘i Creeper (Oreomystis mana) increased, and that all other native birds showed stable trends and exhibited no evidence of declining trends as has been seen elsewhere in much of Hawai‘i. Trends for all alien birds were also stable, except that House Finch (Carpodacus mexicanus) density has declined. In the lower study area, Hawai‘i Creeper and Hawai‘i ‘Ākepa (Loxops c. coccineus) showed increasing trajectories, and densities have declined for the other native species. Within the reforested upper study area, densities increased for three common native species—Hawai‘i ‘Amakihi (Hemignathus virens), ‘I‘iwi (Vestiaria coccinea), and ‘Apapane (Himatione sanguinea)—and two alien species—Japanese White-eye (Zosterops japonicus) and House Finch. Bird trends at the Hakalau refuge provide some of the first results of habitat improvement for forest birds in Hawai‘i. Restoring tree cover in open pasture and assisting recovery of high-quality habitat benefits both endangered and abundant native birds

Hawai'i↗
USGS2010

Changes in prevalence of avian malaria on the Alakai`i Plateau, Kaua`i. Hawai`i

We determined prevalence of malarial infections in samples of native and non-native forest birds that were sampled at three locations on the Alaka`i Plateau between 1994-1997 and again between 2007-2009. The three sites spanned the elevational range of the plateau and were located at Kawaikōī Stream (1100 m), the upper drainage of Mōhihi Stream (1250 m) and the vicinity of Halepa`akai Stream near Sincock’s Bog (1350 m). We detected a dramatic and significant increase in prevalence of avian malaria both at the lower (Kawaikōī) and upper (Halepa`akai) ends of the Alaka`i Plateau during the past decade. Overall prevalence of infection increased threefold from 11% to 30% at Kawaikōī Stream and tenfold from 2% to 20% at Halepa`akai Stream. Much of this increase is likely a result of local transmission, since two sedentary native species, `Elepaio and Kaua`i `Amakihi, have experienced some of the largest increases in prevalence. Curiously, prevalence has not changed significantly at Mōhihi Stream and remains at approximately 10%. We also detected avian trypanosomes ( Trypanosoma sp. ) in both recent and historic blood samples from Nutmeg Mannikins ( Lonchura punctulata ) that were captured on the plateau. This is the first report of this mosquito-transmitted blood protozoan from the Hawaiian Islands and evidence indicates that it has been a previously undetected blood parasite in the islands for at least 15 years and likely longer. We found no evidence to indicate that the parasite has spread to native Hawaiian forest birds, but our sample sizes are limited. While our study was not designed to detect the specific factors responsible for the changes in prevalence of malaria at lower and upper portions of the plateau, the results are consistent with predicted increases in prevalence that might be expected in a warming climate and clearly show that environmental conditions necessary to support transmission of malaria now exist throughout major portions of the Alaka`i Plateau. Additional field work to identify larval habitat for mosquitoes, adult mosquito distribution and density, and the relative role of human activity, feral ungulates, and interactions between changing climatic conditions and the deeply dissected topography of the plateau may help to identify why some areas have experienced significant increases in malarial prevalence.

Hawaii↗
USGS2017

Pacific Island landbird monitoring report, Hawaiʻi Volcanoes National Park, 2015-2016: Tract groups 1 and 2

Hawaiʻi Volcanoes National Park (HAVO) was surveyed for landbirds and landbird habitat from February through April 2015 and February through April 2016. This information provides the second datum in the time-series of Pacific Island Network (PACN) monitoring for long-term trends in landbird distribution, density, and abundance. Initial PACN surveys were conducted in 2010 and are repeated every five years. The entire survey area was comprised of eight tracts in forest, woodland, and shrub habitat, totaling 26,364 ha. Each tract was surveyed using point-transect distance sampling to calculate estimates of bird abundance and density. In addition to the permanent PACN survey transects, randomly generated point-transects were also surveyed, allowing for a split panel sampling design. A total of 14,061 bird detections of twenty-eight species were recorded during point counts; 8 species were native to Hawaiʻi and 20 species were non-native. ʻApapane (Himatione sanguinea) and Hawaiʻi ‘Amakihi (Chlorodrepanis virens virens) were the most abundant and widely distributed native species detected. ‘Ōma’o (Myadestes obscurus), ‘I‘iwi (Drepanis coccinea), and Hawaiʻi Elepaio (Chasiempis sandwichensis) occurred at fewer than 30% of the 757 stations surveyed, and were absent from some tracts. Three species of native birds detected during surveys were endangered—ʻIo (Buteo solitarius), Hawaiʻi Creeper (Loxops mana), and Hawaiʻi ʻAkepa (Loxops coccineus). Two additional endangered species were detected incidentally on transects—Nēnē (Branta sandwicensis) and ʻAkiapolaʻau (Hemignathus wilsoni). Non-native Japanese White-eye (Zosterops japonicus), Northern Cardinal (Cardinalis cardinalis), Japanese Bush Warbler (Horomis diphone), and Yellow-fronted Canary (Crithagra mozambica) were detected throughout most tracts and had the highest relative abundances among non-natives. The remaining species detected occurred at less than 10% of stations surveyed. Sufficient detections to allow density estimation were made for 11 species (5 native and 6 non-native). Changes in species-specific densities by tract were assessed between the initial and current surveys using two-sample z-tests in an equivalence testing framework to determine long-term trends. Differences between densities were highly variable for native species; including increasing, decreasing and stable trends. There were notable increases of ‘I‘iwi and ‘Ōma’o densities in some tracts. However there were also declines of ‘Ōma’o in three tracts, including leeward Northwest Kahuku where birds were detected in 2010 for the first time in over 30 years, but not during this recent survey. ‘I‘iwi densities increased in the high elevation Pāpā tract; however, they declined in the Mauna Loa Strip tract where the species may be vulnerable to avian malaria. Trend results for Hawaiʻi ʻAkepa were inconclusive, but the species occurred at more survey stations than in 2010, and we estimate a density of 0.31 ±0.34 birds/ha in the 10,989 ha Kahuku tract. Hawaiʻi Creeper had in an increasing trend in the Kahuku tract with a density of 0.16 ± 0.07 birds/ha and an inconclusive trend in Honomalino, where there was only one detection in 2016. There was a large expansion in the distribution and abundance of the non-native Yellow-fronted Canary and Japanese Bush Warbler. The Lavender Waxbill (Estrilda caerulescens) was detected in HAVO for the first time. Trend results were variable for other non-native species, but generally maintained stable densities when compared to previous landbird surveys. Several habitat variables were sampled at monitoring stations in each tract. Canopy and understory species were predominantly native, especially in tracts where ungulates have been excluded.

Hawai'i↗
USGS2020

2018 Kaua'i forest bird population estimates and trends

Kaua‘i's native forest birds have experienced steep declines since the beginning of systematic surveys in 1981, and declines have accelerated in recent decades. This report details the analysis of the most recent surveys conducted in 2018. Incorporating the new survey results, long-term trends continue to show sharp declines for all native honeycreeper species with the exception of ‘apapane (Himatione sanguinea), which has stable numbers in core areas of its range. Kaua‘i ‘elepaio (Chasiempis sclateri) continued to decline in the outer portions of its range but increased in the core areas of its range. Abundance estimates of forest birds ranged from slightly higher to slightly lower in most species, indicating a relatively stable period from 2012–2018, and a pause from the rapid declines seen in earlier periods. Many native species now exist in very low numbers, and variation in estimates from survey to survey will increase.

Hawaii↗
USGS2023

Forest bird populations at the Pu‘u Wa‘a Wa‘a Forest Bird Sanctuary and Pu‘u Wa‘a Wa‘a Forest Reserve, Hawai‘i

Endemic Hawaiian forest birds have exhibited dramatic population declines since human colonization of Hawai‘i. The Pu‘u Wa‘awa‘a Forest Bird Sanctuary and adjacent Pu‘u Wa‘awa‘a Forest Reserve on Hawai‘i Island were established in 2002 to conserve endemic forest birds and their habitats. Surveys have been conducted in this area to monitor forest bird populations and their response to management actions since 1979. We analyzed point-transect distance sampling survey data collected between 1990 and 2022 in the Pu‘u Wa‘awa‘a Forest Bird Sanctuary and forested portions of the adjacent forest reserve. There were 20 passerine or psittacine species detected of which 6 were native species and 14 were non-native species. In all years, Hawai‘i ‘amakihi (Chlorodrepanis virens virens), ‘apapane (Himatione sanguinea), and warbling white-eye (Zosterops japonicus) were the most abundant species, and in most years ‘i‘iwi (Drepanis coccinea) was the fourth most abundant species. ‘I‘iwi and Hawai‘i ‘amakihi had stable long-term (1990–2022) population trends, and trends for ‘apapane were inconclusive, while warbling white-eye had upward trends. In recent years (2016–2022), ‘apapane had downward trends, ‘i‘iwi and warbling white-eye had upward trends, and trends for ‘amakihi were inconclusive. Populations of Hawai‘i ‘elepaio (Chasiempis sandwichensis) and the endangered Hawai‘i ‘ākepa (Loxops coccineus) and ‘alawī (Loxops mana) were either locally extirpated or in numbers too low to reliably estimate population densities and trends. The Pu‘u Wa‘awa‘a Forest Bird Sanctuary and adjacent Pu‘u Wa‘awa‘a Forest Reserve are important for the conservation of forest birds on Hawai‘i Island as one of few areas of mesic to dry forests being specifically managed for forest bird conservation. Conservation efforts at the Pu‘u Wa‘awa‘a Forest Bird Sanctuary and Pu‘u Wa‘awa‘a Forest Reserve would benefit from continued annual surveys and regular monitoring, and timely analysis of survey data to track responses in forest bird populations to evaluate and adapt management actions.

Hawaii↗