Hawaii Cooperative Studies Unit (HCSU)

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    Host plant associations of Lepidoptera and implications for forest bird management at Hakalau Forest National Wildlife Refuge
    ( 2022-07-11) Banko, Paul ; Peck, Robert ; Munstermann, Maya ; Jaenecke, Kelly
    Forests dominated or co-dominated by ‘ōhi‘a (Metrosideros polymorpha) are critical to most Hawaiian forest birds, but fungal diseases causing Rapid ‘Ōhi‘a Death (ROD) threaten ‘ōhi‘a-based food webs that support native bird communities on Hawai‘i Island. Caterpillars are the most frequently consumed arthropod prey of native birds and their young and are especially frequent in the diets of one threatened (T) and three endangered (E) species (“listed” species) at Hakalau Forest National Wildlife Refuge (Hakalau): ‘akiapōlā‘au (Hemignathus wilsoni, E), ‘alawī (Hawai‘i creeper; Loxops mana, E), Hawai‘i ‘ākepa (L. coccineus, E), and ‘i‘iwi (Drepanis coccinea, T). Hakalau harbors the largest and most stable populations of listed forest birds in Hawai‘i, presumably due to the availability of food resources and the extent of suitable, managed habitat above the range of mosquito-borne avian malaria. Because a previous study indicated that only a few caterpillar species were important in the diets of listed birds at Hakalau, we investigated the distribution of caterpillars on common host plants available to foraging birds. Eleven native plant species hosted two or more taxa identified to genus or species, with at least seven from ‘ōhi‘a, six from koa (Acacia koa), and five from ‘ākala (Rubus hawaiensis). We identified 16 taxa to genus or species from 9 families, assigning 11 to species. Leaves, which were the focus of our sampling effort, were the substrate used by 20 caterpillar taxa, and dead wood or bark was used by 7 taxa. In a previous study, we classified 19 morphotypes of caterpillar mandibles in the diets of native and alien birds at Hakalau, and in the present study we dissected mandibles from caterpillars that likely matched 10 of those morphotypes. These 10 morphotypes potentially represented >95% of caterpillar prey found in the earlier diet study and were collected from 11 host plant species, with ‘ōhi‘a hosting 8 morphotypes, 4 of which were exclusive to ‘ōhi‘a. The most widely hosted morphotype was found on all 11 plant species that we sampled, including ‘ōhi‘a, but the other 9 morphotypes were found on 1–7 hosts. As shown by the previous diet study, each of the listed bird species consumed caterpillar prey consisting mostly of combinations of two morphotypes drawn from a pool of only five, indicating a high degree of specialization. In the present study, we collected three of the five key morphotypes only on ‘ōhi‘a, highlighting the importance of this tree to listed bird species. Because ‘ōhi‘a forests in Hakalau remain vulnerable to ROD, measures to mitigate the impacts of reduced ‘ōhi‘a cover are important to consider from the perspective of forest bird food webs and diet. Ongoing reforestation of former pasturelands with koa and common understory species should provide alternative caterpillar prey for forest birds. Our results and information from the literature indicate that koa supports, to varying degrees, nearly all forest birds at Hakalau, while ‘ākala, ‘ōhelo (Vaccinium calycinum), kōlea (Myrsine lessertiana), ‘ōlapa (Cheirodendron trigynum), pūkiawe (Leptecophylla tameiameiae), and māmaki (Pipturus albidus) could benefit bird populations by increasing prey availability and structural complexity in koa-dominated stands. Foraging studies and additional research to identify species and host plant associations of important forest bird prey, including caterpillars and other arthropods, can help managers evaluate the complex interactions between native forest birds and their food webs and habitats.
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    2021 Tinian Island forest bird abundance estimates
    ( 2022-05-26) Camp, Richard J. ; Bak, Trevor ; Genz, Ayesha S.
    The U.S. Navy, through Micronesian Environmental Services, surveyed landbirds in the Military Lease Area on Tinian Island in May and June 2021 using point-transect distance sampling methods. There were 2,074 individuals of 14 species detected during 123 point counts. Six species were detected during >50% of the counts and were observed at relatively high abundances, while eight species occurred at <50% of the counts and were uncommon to rare. Densities of native landbirds in the Military Lease Area ranged from the uncommon Mariana kingfisher (Todiramphus albicilla) at 0.46 birds/ha (95% confidence interval [CI] = 0.33–0.63) to the very abundant bridled white-eye (Zosterops conspicillatus) at 102.63 birds/ha (95%CI = 86.70–122.91). Most distances recorded during the 2021 Military Lease Area survey were rounded to distance intervals of 0 and 5. Measuring exact distances of detected animals is preferable to collecting distances grouped into bins or rounding. Direct comparison with previously published estimates was not possible because of changes in the sampling frame; however, densities of six species were greater, two were smaller, and one was similar to the 2008 survey estimates for the Hagoi, Diablo, and Masalog regions. Our findings indicate that the landbird community in the Military Lease Area appears to be dynamic and resilient.
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    Hawaiian forest bird conservation strategies for minimizing the risk of extinction: biological and biocultural considerations
    ( 2022-04-14) Paxton, Eben H. ; Laut, Megan ; Enomoto, Stanton ; Bogardus, Michelle
    The iconic forest birds of Hawai‘i are facing a conservation crisis. Across the Hawaiian Islands, native forest birds have been experiencing population declines that have accelerated in the last one to two decades. While habitat loss, invasive species, and non-native predators have negatively affected forest bird species for hundreds of years, and continue to do so, introduced diseases, particularly avian malaria, are the greatest threat to forest birds today. Further, climate change has increased temperatures in the high-elevation forests, facilitating the spread of disease into areas that were once largely disease-free. Rapid population declines have now (2022) pushed four Hawaiian honeycreeper species to the brink of extinction: the endangered ‘akikiki (Oreomystis bairdi) and ‘akeke‘e (Loxops caeruleirostris) on Kaua‘i Island, and kiwikiu (Pseudonestor xanthophrys) and ‘ākohekohe (Palmeria dolei) on Maui Island. The biologists that study these birds strongly agree that without a rapid conservation response to the threat of increasing disease mortality there is a high probability these species will go extinct in the coming decade. To help evaluate alternative conservation strategies for minimizing the risk of extinction, we convened diverse groups of experts with broad experience in Hawai‘i forest birds and ecosystems, as well as the management approaches being considered, to assess the probability of success of alternative management actions. In addition to assessing this crisis from a biological perspective, we convened a group of Native Hawaiian participants that have a strong connection to the forest birds, forests, and the integration of their culture in natural and biocultural resource management. They give voice to the significance of forest birds to Native Hawaiians and provide their perspectives on alternative management actions. Broadly, the three alternative management actions being considered to prevent the extinction of forest birds from the increasing threat of disease are (1) landscape-level mosquito control through the Wolbachia incompatible insect technique, (2) captive care, and (3) conservation translocations. The two key components of the problem of preventing extinction in these four bird species is time and risk. For each species, very few individuals remain, and they are all in danger of imminent extinction. Each management action takes time to implement, which might exceed the actual time to extinction. Additionally, each of these conservation actions has potential benefits and inherent risks, as well as substantial uncertainty in terms of being successful. Native Hawaiian perspectives and considerations also vary across the conservation actions. The expert evaluations summarized in this report provide a broad assessment of conservation strategies that could be undertaken to prevent the extinction of ‘akikiki, ‘akeke‘e, kiwikiu, and ‘ākohekohe. While this report does not recommend specific actions, the information is intended to support decision-makers as they assess which, if any, conservation strategies to pursue. // Ke hālāwai nei nā manu o ka nahele o Hawai‘i me ka pōpilikia maluō. Ma ka pae ‘āina ‘o Hawai‘i, ke emi mai nei nō ka nui manu a keu aku ma nā makahiki he 10 a 20 i hala aku nei. I loko nō o ka pā hewa o ka manu no nā makahiki he lō‘ihi a he mau haneli i ka nele o kahi e noho ai, ka lāhulu komo hailapu, a me ka po‘ii‘a malihini, ‘o ka ma‘i malihini, ‘o ia ho‘i ka avian malaria, ka mea nui e pau nei ka manu ‘ānō. Ua pi‘i pū ho‘i ka mehana o ka nahele o nā wao ki‘eki‘e a‘e i ka mehana honua e laha ai ua ma‘i nei i nā wahi loa‘a mua ‘ole o ua ma‘i nei. Ua lilo ka pau ‘emo ‘ole ‘ana o ka manu he kumu e pau nei ka ‘ehā lāhulu manu mūkīkī i ka make loa: ‘o ka ‘akikiki (Oreomystis bairdi) lāua me ka ‘akeke‘e (Loxops caeruleirostris) ma ka mokupuni ‘o Kaua‘i a me ke kiwikiu (Pseudonestor xanthophrys) lāua me ka ‘ākohekohe (Palmeria dolei) ma ka mokupuni ‘o Maui. Ua lōkahi ka mana‘o o nā akeakamai kālaimeaola nāna e noi‘i ana i kēia po‘e manu, he nui loa ka papaha o ka pau o ua mau lāhulu nei i ka make loa i loko o nā makahiki he ‘umi e hiki mai auane‘i ke pa‘a ‘ole ke ki‘ina ho‘omaluō e lapa‘au ai. I mea e kālailai ‘ia ai nā ka‘akālai ho‘omaluō e emi ai ka pau loa ‘ana o ka manu i ka make loa, ua ho‘ohui ‘ia nā mea mākaukau o nā ‘ano like ‘ole nona ka ‘ike laulā i ka manu o ka nahele a kaiaola o Hawai‘i a me nā ala ho‘omalu e no‘ono‘o ‘ia ana e noi‘i ai i ka papaha o ka puka o ua mau ki‘ina ho‘omalu nei. Ma waho o ka noi‘i i ka pōpilikia ma ke kuana‘ike kālaimeaola, ua ho‘ohui pū ‘ia he hui o nā kānaka Hawai‘i nona ka pilina ikaika i ka manu o ka nahele, ka nahele, a me ka ‘āwili ‘ia o ka mo‘omeheu Hawai‘i ma ka ho‘omalu kumuwaiwai ao kūlohelohe e komo ai ka mana‘o i ka mea nui o ka manu i ke kānaka Hawai‘i me ka hāpai pū ‘ia o ka mana‘o no nā ki‘ina ho‘omalu pū kekahi. Ma ka laulā, he ‘ekolu ki‘ina ho‘omalu e no‘ono‘o ‘ia nei he ala e pau ‘ole ai ka manu o ka nahele i ka make loa, 1) ke kāohi makika ma o ka Wolbachia incompatible insect technique, 2) ka hānai ka‘awale, a me 3) ka ho‘omaluō ka‘awale. ‘O ka manawa a me ka ‘a‘a i ka hana nā kumuloli nui ‘elua o ke pani i ka pau ‘ana o kēia mau lāhulu manu ‘ehā i ka make loa. No kēlā me kēia lāhulu, kāka‘ikahi nō ke koe ‘ana mai o kona mau manu a ke hālāwai maoli nei nō me ka pōpilikia o pau i ka make loa. He wā ka mea e pono ai kēlā me kēia ki‘ina ho‘omalu e hele ana paha a ma ‘ō aku o ka manawa e pau ai ua mau manu nei i ka make loa. He hopena maika‘i a maika‘i ‘ole nō paha ko kēia mau ki‘ina ho‘omalu, a pēlā pū ke kānalua nui i ka puka a me ka puka ‘ole nō paha. ‘Oko‘a pū ke kuana‘ike o ke kānaka Hawai‘i no kēlā me kēia ki‘ina ho‘omalu. Hō‘ike nā mana‘o o nā mea mākaukau i hō‘ulu‘ulu ‘ia ma kēia mo‘olelo he ‘ike laulā no nā ki‘ina ho‘omaluō e lawelawe ‘ia e pani ‘ia ai ka pau ‘ana o ka ‘akikiki, ka ‘akeke‘e, ke kiwikiu, a me ka ‘ākohekoke i ka make loa. I loko nō o ka hāpai ‘ole ‘ia o nā ki‘ina pono‘ī, i mea ho‘i ka ‘ike o loko e kāko‘o ‘ia ai nā mea nona ka mana ho‘oholo ma ke koho paha i ke ki‘ina ho‘omaluō e ‘imi ‘ia aku.
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    Forest bird populations at the Big Island National Wildlife Refuge Complex, Hawai‘i
    ( 2022-04-13) Kendall, Steven J. ; Rounds, Rachel A. ; Camp, Richard J. ; Genz, Ayesha S.
    Endemic Hawaiian forest birds have experienced dramatic population declines. The Big Island National Wildlife Refuge Complex (BINWRC) was created for conservation of endangered Hawaiian forest birds and their habitats. Surveys have been conducted at two units of BINWRC to monitor forest bird populations and their response to management actions. We analyzed survey data from 1987 to 2019 at the Hakalau Forest Unit (HFU) and from 1995 to 2019 at the Kona Forest Unit (KFU). We analyzed three strata at HFU: open-forest, closed-forest, and pasture, and two strata at the KFU: upper (>1524 m elevation) and lower (<1524 m). In all years, ‘i‘iwi (Drepanis coccinea), ‘apapane (Himatione sanguinea), and Hawai‘i ‘amakihi (Chlorodrepanis virens virens) were the most abundant species at HFU. The three endangered forest bird species, Hawai‘i ‘ākepa (Loxops coccineus), ‘alawī (Loxops mana, also known as Hawai‘i creeper) and ‘akiapōlā‘au (Hemignathus wilsoni), had much lower densities. The most abundant species at KFU was ‘apapane, followed by Hawai‘i ‘amakihi and warbling white-eye (Zosterops japonicus) at much lower densities. At HFU we found a continuation of several trends observed in previous analyses from 1987–2012, with most species’ trends upward in pasture stratum, stable in the open-forest stratum, and downward in the closed-forest stratum. However, when we looked at the most recent decade at HFU, more species were showing downward trends in all three strata. At KFU results were mixed, with more species’ trends downward in the upper stratum and more species’ trends upward in the lower stratum. Populations of endangered forest species were either locally extirpated at KFU or in numbers too low to reliably estimate population densities. Both units in the BINWRC are important for conservation of forest birds on Hawai‘i Island, and our results show that HFU supports the majority of the three endangered forest bird species found on Hawai‘i Island. Our analysis also shows the importance of continuous monitoring and timely analysis to track forest bird populations. With the additional data provided by continued surveys, we determined conclusive population trends for species whose trends were previously inconclusive. Knowing current population densities, abundances, and trends allows managers to evaluate and adapt management actions to support forest bird conservation at the BINWRC.
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    2019–2021 Palila abundance estimates and trend
    ( 2022-01-24) Genz, Ayesha S. ; Brinck, Kevin W. ; Asing, Chauncey K. ; Berry, Lainie ; Camp, Richard J. ; Banko, Paul C.
    The palila (Loxioides bailleui) population on Mauna Kea Volcano, Hawai‘i Island, was estimated from annual surveys in 2019−2021, and a trend analysis was performed on survey data from 1998−2021. The 2019 population was estimated at 1,030−1,899 birds (point estimate: 1,432), the 2020 population was estimated at 964−1,700 birds (point estimate: 1,312), and the 2021 population was estimated at 452−940 birds (point estimate: 678). Since 1998, a visual inspection of the size of the area containing palila detections on the western slope based on the minimum/maximum elevations has not shown a substantial change, indicating that the range of the species has remained stable; although this area represents only about 5% of its historical extent. During 1998−2005, palila numbers fluctuated between 4,000 and 6,000, followed by a steep decline. After 2010, palila estimates stabilized around an abundance of 2,000 with a much slower rate of decline. The decline during 1998−2021 was on average 229 birds per year with very strong statistical support for an overall downward trend in abundance. Over the 23-year monitoring period, the estimated rate of change equated to an 89% decline in the population.
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    Hawaiian hoary bat acoustic surveys on Marine Corps Base Hawaii, 2019-2021
    ( 2021-11-11) Pinzari, Corinna A. ; Montoya-Aiona, Kristina M. ; Gross, Danielle N. ; Courtot, Karen N.
    The endangered Hawaiian hoary bat (Lasiurus semotus, Vespertilionidae, also known as Aeorestes semotus and ‘ōpe‘ape‘a) occurs on all the principal volcanic islands in Hawai‘i. Advances in acoustic bat monitoring techniques have contributed to the body of knowledge of bat activity and behavior in many areas of the State of Hawai‘i; however, there is still much that is unknown about the population and seasonal distribution of Hawaiian hoary bats on O‘ahu. A two-year acoustic survey for presence of Hawaiian hoary bats was conducted at 17 stations across four Marine Corps Base Hawaii (MCBH) properties on O‘ahu to document distribution, seasonal patterns, and foraging activity. Bats were confirmed present at all properties; MCBH Kaneohe Bay on Mōkapu Peninsula, Marine Corps Training Area Bellows (MCTAB) in Waimanalo, Camp H M Smith in Halawa Heights, and Puuloa Range Training Facility (RTF) on the ‘Ewa coastal plain. Hawaiian hoary bats were recorded in airspace at all four properties during important periods of Hawaiian hoary bat life history, including periods of pregnancy, lactation, and pup fledging; however, overall presence was low. Foraging activity as identified from characteristic feeding buzzes was very rare and was recorded on only three nights over the entire study. Within-night bat detection pooled for all nights and stations at each property showed that bat activity was mostly confined to the first several hours of the night at MCBH Kaneohe Bay and Puuloa RTF, whereas bat activity was spread throughout the night at Camp H M Smith and MCTAB. Overall, detection frequency was low (year 1 = 0.009, year 2 = 0.007, average = 0.008) at the study sites on O‘ahu compared to results from acoustic monitoring studies on the islands of Maui and Hawai‘i. However, the low rate of bat presence on MCBH properties is consistent with recent studies at other locations on the Island of O‘ahu. Monitoring the seasonal presence and distribution of Hawaiian hoary bats on MCBH facilities, especially at forest and wetland habitats, could contribute to the broader scientific understanding of island-wide distribution and behavior on O‘ahu, which is essential for species recovery planning and implementation of best management practices.
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    Effectiveness of rapid 'ōhi'a death management strategies at a focal disease outbreak on Hawai'i Island
    ( 2021-02-03) Roy, Kylle ; Granthon, Carolina ; Peck, Robert W. ; Atkinson, Carter T.
    The ongoing spread of rapid ‘ōhi‘a death (ROD) in the Hawaiian Islands threatens the long-term sustainability of ‘ōhi‘a lehua (Metrosideros polymorpha) forests throughout the state. First identified in the Puna district of Hawai‘i Island in 2014, the disease caused by the novel fungi Ceratocystis lukuohia and Ceratocystis huliohia has now spread island-wide and was recently detected on Kaua‘i, O‘ahu, and Maui. The leading hypothesis for the spread of ROD is through airborne ambrosia beetle frass particles that contain viable Ceratocystis propagules, thus management efforts focus on containing this frass. At the time of this study (2017–2018), the Waipunalei site was the northernmost outbreak of ROD on Hawai‘i Island. The focal nature of the outbreak and accessibility of the location provided the opportunity to monitor the effectiveness of two types of proposed management methods to reduce the airborne spread of potentially infective ambrosia beetle frass: tree felling and insecticide treatments. We placed 23 passive environmental samplers (PES), which monitored for airborne frass and wood particles containing C. lukuohia and C. huliohia in a grid that spanned the outbreak area over 22 weeks. Cross-vane panel traps with 1:1 methanol:ethanol lures were attached to nine of the PES to document wood-boring ambrosia and cerambycid beetle populations during the latter three months of the study. Monitoring with PES began three weeks before management and continued for one month after the last infected trees were felled. Glass microscope slides from the 23 PES were examined for airborne ambrosia beetle frass and wood particles by microscopy. DNA was extracted from the slides and tested by qPCR (quantitative polymerase chain reaction) for C. lukuohia and C. huliohia. We also investigated the correlation of beetle gallery counts with tree height and tested the efficacy of Bifen I/T insecticide (active ingredient: bifenthrin 7.9%) for preventing beetle attacks on the cut surface of ‘ōhi‘a bolts (tree stem sections). Beetle trapping data revealed that the area supports a diverse community of wood-boring beetles, some of which likely attack ‘ōhi‘a and may facilitate the spread of ROD. The number of beetle galleries on felled ‘ōhi‘a trees decreased linearly as tree height increased. We also observed significantly fewer beetle attacks on Bifen I/T treated ‘ōhi‘a bolts than non-treated bolts, but gallery formation nearly ceased in both treated and control bolts by week three. Ceratocystis lukuohia DNA was detected twenty-six times and C. huliohia was detected five times in the PES throughout this study. DNA detections were correlated to frass and wood counts, and the number of felled trees were correlated to wood particle counts but not frass counts. Both the timing and distribution of detections across the sampling grid indicate that tree felling may have reduced airborne detections of Ceratocystis DNA soon after tree felling was completed. A subsequent increase in detections after tree felling ceased may indicate that incomplete removal of infected trees and the appearance of new infections in previously asymptomatic trees could have allowed airborne detections of potentially infectious fungal propagules to once again increase.
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    Field trials to test new trap technologies for monitoring Culex populations and the efficacy of the biopesticide formulation VectoMax® FG for control of larval Culex quinquefasciatus in the Alaka'i Plateau, Kaua'i, Hawaii
    ( 2021-01-18) LaPointe, Dennis A. ; Black, Theodore V. ; Riney, Michael ; Brinck, Kevin W. ; Crampton, Lisa H. ; Hite, Justin
    Mosquito-borne avian malaria Plasmodium relictum is a key limiting factor for endemic Hawaiian forest birds. In the past decade, populations of Kaua‘i’s endemic forest birds have been in a steep decline due to an increase in malaria transmission. To evaluate the use of available biopesticides for short-term mosquito control we tested the efficacy of the biopesticide VectoMax® FG against Culex quinquefasciatus larvae in naturally occurring perched stream pools, seeps, and ground pools in forest bird habitat in Kaua‘i’s remote Alaka‘i Plateau. We also tested the efficacy of conventional and newer traps and attractants for the capture of adult Culex quinquefasciatus in Hawaiian rain forests and monitored adult mosquito populations at the Kaua‘i field site. During field trials conducted on Hawai‘i Island we captured more Culex quinquefasciatus in gravid traps than in host-seeking traps. Among the host-seeking traps, Biogents BG-Sentinel 2 traps baited with CO2 and BG-Lure caught more Culex quinquefasciatus and Aedes japonicus japonicus than CDC (Centers for Disease Control and Prevention) traps baited with compressed CO2, CDC traps baited with dry ice, or Biogents BG-Sentinel 2 traps baited with BG-Lure and octenol but not CO2. Both Biogents BG-Sentinel 2 and CDC miniature traps baited with compressed CO2 or dry ice captured significantly more Culex quinquefasciatus than Biogents BG-Sentinel 2 traps baited with octenol and BG-Lure but without CO2. We also found that gravid traps baited with timothy hay infusions caught significantly more Culex quinquefasciatus than traps baited with either a commercial gravid mosquito attractant or an infusion made with pelleted rabbit feed. Traps baited with an infusion of timothy hay and donkey dung were the most effective for Culex quinquefasciatus. On Kaua‘i, we operated Biogents BG-Sentinel 2 traps baited with CO2 and gravid traps and captured 29 mosquitoes in 182 trap-nights from October–November 2016 and 126 mosquitoes in 254 trap-nights from September–October 2017. Contrary to our findings on Hawai‘i Island, most mosquitoes (96%) were captured in Biogents BG-Sentinel 2 traps indicating considerable site-to-site variability in trap efficacy. Weekly adult trapping on Kaua‘i indicates Culex quinquefasciatus populations peaked in October but provided no reliable evidence that larval control had any significant effect on adult populations. Overall, VectoMax® FG was very effective at larval control reducing larval abundance by 95% at 48 hours and out to 1-week post-treatment. Treatment was most effective (100% at 1-week post-treatment) in perched pools when early instar larvae were present and least effective in seeps when pupae and fourth instar larvae were most common. Although post-treatment counts fluctuated dramatically, we observed no evidence of population level impacts to the two most common non-target invertebrates: the water strider Microvelia vagans and endemic damselfly naiads (Megalagrion sp.). VectoMax® FG appears to be an effective and safe biopesticide for the local control of Culex quinquefasciatus larvae in forest bird habitat in the Alaka‘i Plateau. Further studies will be necessary to determine if local larval control significantly reduces adult mosquito abundance and, ultimately, avian malaria transmission, and if there are long term, non-target effects associated with repeated use of VectoMax® FG in natural Hawaiian waterways.
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    2018 Kaua'i forest bird population estimates and trends
    ( 2020-11-11) Paxton, Eben H. ; Brinck, Kevin W. ; Crampton, Lisa H. ; Hite, Justin ; Costantini, Maria
    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.
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    Forest bird population trends within Haleakalā National Park
    ( 2020-09-16) Brinck, Kevin W.
    In 2017, the comprehensive east Maui bird surveys allowed for an update in status and evaluation of trends in bird populations within Haleakalā National Park. This report describes a finer-scale analysis of the park lands, distinguishing between the upper Kīpahulu Valley plus adjacent high-elevation areas compared to the rest of the park. I report abundance estimates and assess trends for six native and three non-native bird species within the park. Overall abundance estimates are consistent with those in previous reports, but there is some evidence for different densities between the two areas of the park, and relative densities of some species may vary from survey to survey. With two possible exceptions (native ‘apapane and non-native red-billed leiothrix), recent trends indicate that bird populations are in decline.