Geology topics

Paul C. Banko

Publications and source records attributed to Paul C. Banko.

At least 37 records · Page 2Linked to original sources

USGS2022

2019-2021 Palila abundance estimates and trend

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.

Hawaii↗

USGS2022

Host plant associations of Lepidoptera and implications for forest bird management at Hakalau Forest National Wildlife Refuge

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.

Hawaii↗

USGS2020

Linking plant and animal functional diversity with an experimental community restoration in a Hawaiian lowland wet forest

Testing how plant restoration influences animal taxonomic and functional diversity can shift restoration projects beyond mainly plant community considerations. We incorporated multi-trophic interactions into restoration by describing an ongoing functional trait-based restoration experiment in Hawaiian lowland tropical wet forest (Liko Nā Pilina Experiment), where litter arthropods are examined from a functional perspective thereby linking plants and higher trophic levels. We hypothesized that (1) communities with greater plant functional trait diversity would have cascading effects through food webs, increasing animal diversity and network complexity, and (2) increases in animal species and network complexity would be stronger for restoration efforts in plant communities with more complementary functional traits than those with more redundant traits. We examined experimental treatments of planted communities with the same species richness but with different plant functional trait profiles based on (1) rates of expected carbon turnover (slow or moderate), and (2) the similarity of their functional trait measurements (redundant or complementary), as determined by functional dispersion calculations. Initial data on arthropod communities and leaf litter decomposition rates revealed linkages between plant functional traits and arthropod community diversity. Overall, we argue that a more comprehensive evaluation of restoration accounts for both functional diversity and the multi-trophic nature of animal and plant communities. Developing restoration projects based on plant functional traits that influence both plant and invertebrate species provides a new paradigm, and the incorporation of both native and non-native (but non-invasive) plants shows promise in restoring ecosystem function in disturbed lowland tropical forests.

Hawaii↗

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↗

USGS2018

Invasive rat control is an efficient, yet insufficient, method for recovery of the critically endangered Hawaiian plant hau kuahiwi (Hibiscadelphus giffardianus)

Biological invasions of rodents and other species have been especially problematic on tropical islands. Invasive Rattus rattus consumption of Hibiscadelphus giffardianus (Malvaceae; common Hawaiian name hau kuahiwi) fruit and seeds has been hypothesized to be the most-limiting factor inhibiting the critically endangered tree, but this has not been experimentally tested, and little is known about other factors affecting seed dispersal, germination, and seedling establishment. Thus, we do not know if rat removal is sufficient to increase hau kuahiwi recruitment. This study aims to evaluate the effect of rat population control on the ability of hau kuahiwi to retain fruit and establish seedlings. We compared hau kuahiwi fruiting and seedling recruitment in a stand treated to reduce rat abundance and a neighbouring control stand. Fruit retention increased following treatment but seedling establishment did not. Although rat control improves the ability of hau kuahiwi to retain fruit, other, presently unknown inhibitors to seed dispersal, germination, and/or seedling development remain. Seed and seedling predation by other species, competition from numerous invasive plant species, unsuitable climate, and/or other factors may be primary inhibitors in the absence of rats, but we emphasize that progressive isolation of these factors at individual hau kuahiwi life stages may be necessary to identify the remaining threats to the conservation of this critically endangered plant.

PLoS ONE↗

USGS2018

Evaluating the long-term management of introduced ungulates to protect the palila, an endangered bird, and its criticial habitat in subalpine forest of Mauna Kea, Hawai'i

Under the multiple-use paradigm, conflicts may arise when protection of an endangered species must compete with other management objectives. To resolve such a conflict in the Critical Habitat of the endangered Hawaiian honeycreeper, palila (Loxioides bailleui), federal courts ordered the eradication of introduced ungulates responsible for damaging the māmane (Sophora chrysophylla) forest on which palila depend. During 1980–2011, a total of 18,130 sheep (Ovis aries and O. gmelini musimon) and 310 goats (Capra hircus) were removed from Palila Critical Habitat (PCH) primarily by public hunters (54%) and secondarily by aerial shooting. Nevertheless, our analysis indicates that ungulates have increased over time. Palila numbers have declined sharply since 2003 due to long-term habitat degradation by ungulates and drought. Although culling ungulate populations has allowed some habitat improvement, their complete removal is necessary for palila to recover, especially given the potential for continued drought. Introduced predators are being controlled to reduce palila mortality, māmane and other native trees are being planted to restore some areas, and fencing is being constructed to prevent ungulate immigration. Funds are recently available for more effective eradication efforts, which are urgently needed to eliminate browsing damage in PCH and protect the palila from extinction.

Hawaii↗

USGS2018

2017-2018 Palila abundance estimates and trend

The palila (Loxioides bailleui) population was surveyed annually from 1998–2018 on Mauna Kea Volcano to determine abundance, population trend, and spatial distribution. In the latest surveys, the 2017 population was estimated at 1,177−1,813 birds (point estimate: 1,461) and the 2018 population was estimated at 778−1,420 (point estimate: 1,051). Only two palila were detected outside the core survey area during a mountain-wide survey in 2017, suggesting that most, if not all, palila inhabit the western slope during the annual survey period. Since 1998, the size of the area containing palila detections on the western slope did not show a significant change, suggesting that the range of the species has remained stable; although this area represents only about 5% of its historical extent. During 1998−2003, palila numbers fluctuated moderately (coefficient of variation [CV] = 0.20). After peaking in 2003, population estimates declined steadily through 2011; since 2010, estimates have continued to decline at a slower rate. The average rate of decline during 1998−2018 was 168 birds per year with very strong statistical support for an overall declining trend in abundance. Over the 21-year monitoring period, the estimated rate of change equated to a 76% decline in the population.

Hawai`i↗

USGS2017

Changes in vocal repertoire of the Hawaiian crow, Corvus hawaiiensis,from past wild to current captive populations

For most avian species, social behaviou r is critically important for survival and reproductive success. Many social behaviours in birds are culturally transmitted, and as bird populations decline across the globe, important elements of these behaviours may be lost. The Hawaiian crow or 'alalā, Corvus hawaiiensis , is a socially complex avian species that is currently extinct in the wild. As in other oscine passerines, vocalizations in the 'alalā may be culturally transmitted. We compared the vocal repertoire of three of the last four wild 'alalā pairs from the early 1990s to three current captive pairs on the Island of Hawai'i to determine how acoustic behaviour has been affected by changes in their social and physical environment. Over 18 h of recordings from wild breeding pairs were analysed and compared with 44 h from captive breeding pairs. Calls were placed into five putative behavioural categories: (1) alarm, (2) territorial broadcast, (3) aggression, (4) submission and (5) courtship. There was little difference in the overall number and diversity of call types among wild versus captive birds. However, the repertoire was significantly different. Territorial broadcast calls, common components of the wild repertoire, were absent from the captive repertoire. In addition, wild birds had twice the number of alarm calls and had a higher call rate than captive birds. Our results show how socially learned behaviours may change over relatively short periods for an entire species. Understanding how the vocal repertoire and the functional context of vocalizations change may provide useful information for ongoing efforts to reintroduce the 'alalā into the wild.

Hawai'i↗

USGS2017

Efforts to eradicate yellow crazy ants on Johnston Atoll: Results from crazy ant strike teams X, XI and XII (June 2015–December 2016)

Efforts to eradicate invasive yellow crazy ants (Anoplolepis gracilipes; YCA) on Johnston Atoll have been continuous since their discovery in 2010. Through 2014, a variety of commercial and novel formicidal baits were tested against the ant, but none proved capable of eradication. More recently, polyacrylamide crystals (“hydrogel”) saturated with a sucrose solution containing the insecticide dinotefuran has been shown to be effective over large areas when applied against YCA alone or sequentially with a protein-based cat food bait. During June 2015–December 2016, Crazy Ant Strike Teams (CASTs) conducted treatment and monitoring efforts across an infestation of about 57 ha on Johnston Atoll. Following three infestation-wide treatments (primarily using hydrogel) during 2015, YCA were reduced 98% and surviving nests became difficult to find. Subsequently, a protocol designed to detect ants at low abundance that combined hand searching with a high density of baited monitoring stations (12 stations/0.25 ha; HST protocol) was employed within a network of 50 x 50 m cells that subdivided the infestation. During 2016 YCA were found at numerous locations using this method and standard grid-based bait monitoring surveys. Overall, 65 cells where YCA were detected, or cells adjacent to detections, were treated with hydrogel or cat food bait. YCA were not detected during four monitoring events each separated by at least one week, on 85% of these cells after 1–3 treatments, but it was necessary to treat several cells 4–7 times before YCA were eliminated. Results from HST searches allowed us to estimate the probability that YCA were detected when present in an area when searched using that method. Based on this probability, it was determined that areas would have to be searched three times without YCA being detected to allow 93% certainty that the ants were absent. The level of certainty increased to 99% when the search was conducted four times and YCA were not found. Overall, the likelihood of eradicating YCA on Johnston Atoll appears high using existing protocols.

Hawai'i↗

USGS2016

State-space modeling of population sizes and trends in Nihoa Finch and Millerbird

Both of the 2 passerines endemic to Nihoa Island, Hawai‘i, USA—the Nihoa Millerbird ( Acrocephalus familiaris kingi ) and Nihoa Finch ( Telespiza ultima )—are listed as endangered by federal and state agencies. Their abundances have been estimated by irregularly implemented fixed-width strip-transect sampling from 1967 to 2012, from which area-based extrapolation of the raw counts produced highly variable abundance estimates for both species. To evaluate an alternative survey method and improve abundance estimates, we conducted variable-distance point-transect sampling between 2010 and 2014. We compared our results to those obtained from strip-transect samples. In addition, we applied state-space models to derive improved estimates of population size and trends from the legacy time series of strip-transect counts. Both species were fairly evenly distributed across Nihoa and occurred in all or nearly all available habitat. Population trends for Nihoa Millerbird were inconclusive because of high within-year variance. Trends for Nihoa Finch were positive, particularly since the early 1990s. Distance-based analysis of point-transect counts produced mean estimates of abundance similar to those from strip-transects but was generally more precise. However, both survey methods produced biologically unrealistic variability between years. State-space modeling of the long-term time series of abundances obtained from strip-transect counts effectively reduced uncertainty in both within- and between-year estimates of population size, and allowed short-term changes in abundance trajectories to be smoothed into a long-term trend.

Hawai'i↗

USGS2016

Federal collaboration in science for invasive mammal management in U.S. National Parks and Wildlife Refuges of the Pacific Islands

Some of the most isolated islands in the Pacific Ocean are home to US National Parks and Wildlife Refuges. These islands are known for flora and fauna that occur nowhere else, but also for invasive species and other factors which have resulted in the disproportionate extinction of native species. The control of invasive mammals is the single most expensive natural resource management activity essential for restoring ecological integrity to parks in the Hawaiian Islands, American Samoa, and the islands of Guam and Saipan. Science-based applications supporting management efforts have been shaped by longstanding collaborative federal research programs over the past four decades. Consequently, feral goats (Capra hircus) have been removed from >690 km2 in National Parks, and feral pigs (Sus scrofa) have been removed from >367 km2 of federal lands of Hawai‘i, bringing about the gradual recovery of forest ecosystems. The exclusion of other non-native ungulates and invasive mammals is now being undertaken with more sophisticated control techniques and fences. New fence designs are now capable of excluding feral cats (Felis catus) from large areas to protect endangered native waterfowl and nesting seabirds. Rodenticides which have been tested and registered for hand and aerial broadcast in Hawai‘i have been used to eradicate rats from small offshore islands to protect nesting seabirds and are now being applied to montane environments of larger islands to protect forest birds. Forward-looking infrared radar (FLIR) is also being applied to locate wild ungulates which were more recently introduced to some islands. All invasive mammals have been eradicated from some remote small islands, and it may soon be possible to manage areas on larger islands to be free of invasive mammals at least during seasonally important periods for native species.

Conference Paper↗

USGS2016

2015-2016 Palila abundance estimates

The palila (Loxioides bailleui) population was surveyed annually during 1998−2016 on Mauna Kea Volcano to determine abundance, population trend, and spatial distribution. In the latest surveys, the 2015 population was estimated at 852−1,406 birds (point estimate: 1,116) and the 2016 population was estimated at 1,494−2,385 (point estimate: 1,934). Similar numbers of palila were detected during the first and subsequent counts within each year during 2012−2016; the proportion of the total annual detections in each count ranged from 46% to 56%; and there was no difference in the detection probability due to count sequence. Furthermore, conducting repeat counts improved the abundance estimates by reducing the width of the confidence intervals between 9% and 32% annually. This suggests that multiple counts do not affect bird or observer behavior and can be continued in the future to improve the precision of abundance estimates. Five palila were detected on supplemental survey stations in the Ka‘ohe restoration area, outside the core survey area but still within Palila Critical Habitat (one in 2015 and four in 2016), suggesting that palila are present in habitat that is recovering from cattle grazing on the southwest slope. The average rate of decline during 1998−2016 was 150 birds per year. Over the 18-year monitoring period, the estimated rate of change equated to a 58% decline in the population.

Technical Report↗

USGS2015

Current land bird distribution and trends in population abundance between 1982 and 2012 on Rota, Mariana Islands

The western Pacific island of Rota is the fourth largest human-inhabited island in the Mariana archipelago and designated an Endemic Bird Area. Between 1982 and 2012, 12 point-transect distance-sampling surveys were conducted to assess bird population status. Surveys did not consistently sample the entire island; thus, we used a ratio estimator to estimate bird abundances in strata not sampled during every survey. Trends in population size were reliably estimated for 11 of 13 bird species, and 7 species declined over the 30-y time series, including the island collared-dove Streptopelia bitorquata , white-throated ground-dove Gallicolumba xanthonura , Mariana fruit-dove Ptilinopus roseicapilla , collared kingfisher Todiramphus chloris orii , Micronesian myzomela Myzomela rubratra , black drongo Dicrurus macrocercus , and Mariana crow Corvus kubaryi . The endangered Mariana crow (x̄ = 81 birds, 95% CI 30–202) declined sharply to fewer than 200 individuals in 2012, down from 1,491 birds in 1982 (95% CI = 815–3,115). Trends increased for white tern Gygis alba , rufous fantail Rhipidura rufifrons mariae , and Micronesian starling Aplonis opaca . Numbers of the endangered Rota white-eye Zosterops rotensis declined from 1982 to the late 1990s but returned to 1980s levels by 2012, resulting in an overall stable trend. Trends for the yellow bittern Ixobrychus sinensis were inconclusive. Eurasian tree sparrow Passer montanus trends were not assessed; however, their numbers in 1982 and 2012 were similar. Occupancy models of the 2012 survey data revealed general patterns of land cover use and detectability among 12 species that could be reliably modeled. Occupancy was not assessed for the Eurasian tree sparrow because of insufficient detections. Based on the 2012 survey, bird distribution and abundance across Rota revealed three general patterns: 1) range restriction, including Mariana crow, Rota white-eye, and Eurasian tree sparrow; 2) widespread distribution, low abundance, including collared kingfisher, island collared-dove, white-throated ground-dove, Mariana fruit-dove, white tern, yellow bittern, black drongo, and Micronesian myzomela; and 3) widespread distribution, high abundance, including rufous fantail and Micronesian starling. The Mariana crow was dispersed around the periphery of the island in steep forested land-cover types. In contrast, the Rota white-eye was restricted to the high-elevation mesa. Only for the white-throated ground-dove was there a significant difference among cover types, with lower occupancy in open field than in forested areas. Vegetation was included in the best-fit occupancy models for yellow bittern, black drongo, Micronesian myzomela, and Micronesian starling, but vegetation type was not a significant variable nor included in the top models for the remaining five species: white tern, island collared-dove, Mariana fruit-dove, collared kingfisher, and rufous fantail. Given declining population trends, the Rota bird-monitoring program could benefit from establishing threshold and alert limits and identifying alternative research and management actions. Continued monitoring and demographic sampling, in conjunction with ecological studies, are needed to understand why most bird species on Rota are declining, identify the causative agents, and assess effectiveness of conservation actions, especially for the Mariana crow.

Rota↗

USGS2015

Book review: Flight ways: Life and loss at the edge of extinction.

In less than 200 pages, Thom van Dooren aims in his ambitious book, Flight Ways , to reconnect humans empathetically with the rest of the planet's inhabitants, but especially vanishing species. This is asking a lot, but he succeeds—or at least makes great strides—using evocative storytelling and compelling discourse. A number of themes are carefully woven together with the goal of awakening sensitivities, building understanding, and motivating commitment to stopping the decline of populations and species. As one who works in the field of endangered Hawaiian bird research, I found this book illuminating, thought-provoking, and insightful. It probes deeply into the evolution, ecology, and ethics of our interactions with other species and offers useful lessons for thinking about endangered species and extinction in more meaningful ways. It will likely spur self-examination and further inquiry by readers, which can open new lines of communication with the general public about conservation. Review info: Flight Ways: Life and Loss at the Edge of Extinction . By Thom van Dooren, 2014. ISBN 978-0231166188, 193 pp.

Journal of Field Ornithology↗

USGS2015

Ants of the national park of American Samoa

American Samoa makes up the eastern end of the Samoan Archipelago. On the islands of Tutuila, Taʽū and Ofu, the National Park of American Samoa (NPSA) protects about 4,000 ha of coastal, mid-slope and ridge-top forest. While the ant fauna of the Samoan Archipelago is considered relatively well documented, much of NPSA has never been surveyed for ants, leaving the fauna and its distribution poorly known. To address this shortfall, we systematically surveyed ants within the Tutuila and Taʽū units of NPSA using standard methods (hand collecting, litter sifting, and baits) at 39 sites within six vegetation types ranging from 8 to 945 m elevation. Forty-four ant species were identified, 19 of which are exotic to the Samoan Archipelago. Two notoriously aggressive species, Anoplolepis gracilipes and Pheidole megacephala were detected at two and seven sites, respectively. Both of these species largely excluded all other ants from bait, although their impact on ant community composition is unclear. A suite of habitat variables measured at each site was assessed to explain park-wide ant distributions. Of eight variables evaluated, only elevation was associated with ant community structure, as the ratio of native to exotic ant species increased significantly with elevation on Tutuila. Our survey documented two species not previously reported from American Samoa. Strumigenys eggersi, detected at 12 sites, appears to be a new immigrant to the Pacific Basin. A species of Pheidole was collected that likely represents an undescribed species. Solenopsis geminata, an aggressive species first reported on Tutuila in 2002, was not detected during our survey.

America Samoa↗

USGS2015

An assessment of arthropod prey resources at Nakula Natural Area Reserve, a potential site of reintroduction for Kiwikiu (Pseudonestor xanthophrys) and Maui `Alauahio (Parareomyza montana)

Hawaiian forest birds have declined dramatically since humans arrived in the archipelago. Birds from all foraging guilds have been affected but insectivorous species are currently at greatest risk of extinction. On the island of Maui, populations and ranges of the insectivorous kiwikiu (Maui parrotbill; Pseudonestor xanthophrys) and Maui ‘alauahio (Maui creeper; Paroreomyza montana) have declined significantly from historic levels primarily due to habitat loss, predation,disease, and food web disruption, leading to federal listings of endangered species and species of concern, respectively. Recovery plans for these birds include reestablishment of populations in parts of their former range. Nakula Natural Area Reserve on the leeward side of HaleakalāVolcano has been targeted for release of wild-caught or captive-bred individuals. The mesic, montane koa-‘ōhi‘a (Acacia koa-Metrosideros polymorpha) forest at Nakula has been heavily impacted through grazing by feral ungulates, but recent management actions to exclude these animals are promoting forest recovery. The objective of this study was to assess the arthropod prey base at Nakula in preparation for reintroductions of kiwikiu and Maui ‘alauahio. To accomplish that goal, we compared arthropod abundances at Nakula to those at Hanawi Natural Area Reserve and Waikamoi Preserve, areas where kiwikiu and Maui ‘alauahio are currently found. We also identified diets of kiwikiu and Maui ‘alauahio from fecal samples to better understand and evaluate the prey base at Nakula. Assessment methods included clipping branch tips to sample arthropods within the foliage of koa and ‘ōhi‘a, using traps to quantify arthropods on koa and ‘ōhi‘a bark surfaces, counting exit holes to quantify abundances of beetles (Coleoptera) within dead branches of koa, and measuring the density of arthropods within the stems of ‘ākala (Rubus hawaiiensis). The diet of kiwikiu was dominated by caterpillars (Lepidoptera larvae), which comprised 90% of all prey items for 50 adult birds and 98% of all prey for two nestlings. Caterpillars were also the most important prey for Maui ‘alauahio (43% for 104 adult birds) although spiders (Araneae, 16%), beetles (12%) and true bugs, planthoppers and psyllids (Hemiptera; 12%) were also important. Caterpillars were generally the most abundant type of arthropod in the foliage of koa and ‘ōhi‘a, although spiders, beetles and hemipterans were also common. Total arthropod biomass and caterpillar biomass at Nakula was as great, or greater, than that observed at Hanawi and Waikamoi per unit of foliage of both koa and ‘ōhi‘a. Spiders generally dominated the bark fauna on both koa and ‘ōhi‘a at all sites although isopods (Isopoda), millipedes (Myriapoda: Millipeda) and lacewings (Neuroptera) were also abundant at Waikamoi and Hanawi. Total arthropod biomass on bark, as well as the biomass of several individual taxa, was significantly lower at Nakula than the other sites. Our measurement of the density of beetle exit holes in dead koa branches found no difference between Nakula and Waikamoi. Finally, no difference existed in the abundance of arthropods (primarily caterpillars and moth pupae) within ‘ākala stems among sites. With the exception of bark surfaces, our results suggest that the arthropod prey base for birds on primary foraging substrates at Nakula is similar to that found at two sites within the current range of kiwikiu and Maui ‘alauahio. However, our results should be viewed with caution because they are limited to the scale of individual branch, tree, or ‘ākala stem. To complete the assessment, our results should be scaled up to the landscape level by determining the density of each substrate within each site. Key arthropod prey of kiwikiu and Maui ‘alauahio are available at Nakula and, as habitat restoration continues, food abundance should increase to the point at which populations of these birds can be supported.

Hawaii↗

USGS2015

Palila Restoration Research, 1996−2012. Summary and management implications

The Palila Restoration Project was initiated in 1996 by the U.S. Geological Survey to assist government agencies mitigate the effects of realigning Saddle Road (Highway 200) through Palila Critical Habitat (U.S. Fish and Wildlife Service 1998, Federal Highway Administration 1999). Ecological research on the palila (Loxioides bailleui), an endangered Hawaiian forest bird, carried out by the U.S. Geological Survey (formerly organized as the Research Division of U.S. Fish and Wildlife Service) since 1987 and research conducted by the Palila Restoration Project provided the scientific bases for developing a recovery strategy (U.S. Fish and Wildlife Service 2006) and its adaptive implementation. The main objectives of the Palila Restoration Project were to develop techniques for reintroducing the palila to a portion of its former range, investigate the biological threats to the palila and its habitat, and synthesize the existing body of ecological knowledge concerning the palila. Five broad study themes formed the research framework: 1. Population reintroduction and restoration 2. Demography and breeding ecology 3. Habitat use and food ecology 4. Vegetation ecology 5. Predator ecology and management An element that was not included in the research program of the project was the ecology and management of introduced ungulates, which has historically constituted the single greatest threat to Palila Critical Habitat (Banko et al. 2009). The absence of ungulate studies should not be interpreted to mean that we believe ungulates no longer damage palila habitat. Other research has already established that removing alien browsers and grazers from Mauna Kea is essential for the recovery of the subalpine forest on which palila now depend (Scowcroft and Giffin 1983; Scowcroft and Sakai 1983; Scowcroft and Conrad 1988, 1992; Hess et al. 1999). Moreover, the Federal District Court of Hawai‘i has ordered the State of Hawai‘i to remove browsing ungulates from Palila Critical Habitat (Banko et al. 2009, Hess and Banko 2011). This final report summarizes results of Palila Restoration Project research from December 1996 to December 2012. Even though some results contained in this report have been published in scientific journals and other technical reports (Appendix I), they are included here to provide a comprehensive chronicle of all project activities.

Hawaii↗

USGS2015

Efforts to eradicate yellow crazy ants on Johnston Atoll: Results from Crazy Ant Strike Team IX, December 2014-June 2015

The ecologically destructive yellow crazy ant (YCA; Anoplolepis gracilipes ) was first detected on Johnston Atoll in January 2010. Within eight months, the U.S. Fish and Wildlife Service had mobilized its first crazy ant strike team (CAST), a group of biologists dedicated to testing and identifying insecticidal baits to be used to eradicate the ant on the atoll. During December 2014‒May 2015 CAST IX focused on testing hydrogel crystals saturated with sucrose solution (25%) carrying the insecticides thiamethoxam and dinotefuran against YCA. A series of experiments, including artificial nest box trials, and field-based palatability trials and eradication tests on small (500 m2 or 0.05 ha) and large plots (2500 m2 or 0.25 ha), were conducted to test concentrations of thiamethoxam ranging from 0.0005% to 0.01%, and dinotefuran at 0.05%. Additionally, the cat food-based matrix containing dinotefuran (0.05%), the standard bait used to suppress YCA on Johnston since 2011, and textured vegetable protein (TVP) carrying dinotefuran at 0.1% and 0.05% were included in large plot tests. Nest box trials were inconclusive due to a consistent loss of queen and worker ants in control boxes, so they were discontinued. Palatability trials suggested higher dosages of thiamethoxam (0.005 and 0.01%) were less attractive than lower dosages (0.0005 and 0.001%) and controls (sucrose only), but small and large plot experiments failed to identify a thiamethoxam concentration that was consistently effective at killing YCA. In contrast, hydrogel containing dinotefuran was consistently effective, killing >95% of YCA on small and large plots. As expected, the cat food bait effectively reduced YCA abundances, but was slightly less effective than hydrogel containing dinotefuran over time. Three successive, approximately weekly treatments of large plots with hydrogel bait, or other baits followed by hydrogel bait, suggest an increasing overall effectiveness, with no aversion of YCA to the bait. This finding is important in that it indicates that hydrogel bait can be applied at short time intervals, potentially resulting in relatively constant exposure of YCA to highly attractive, yet toxic, sucrose-based bait. TVP performed similar to hydrogel, reducing YCA abundance >92% at both concentrations tested. Finally, dosages of hydrogel containing dinotefuran at 6, 12 and 24 l/0.25 ha were all effective at reducing YCA on large plots. Overall, results from these experiments suggest that hydrogel containing dinotefuran (0.05%) is a promising tool for eradicating YCA on Johnston Atoll.

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