The PCSU and HPI-CESU Technical Reports 1974 - current

Permanent URI for this collectionhttps://hdl.handle.net/10125/357

This collection presents the Pacific Cooperative Studies Unit (PCSU) and the Hawaii-Pacific Islands Cooperative Ecosystem Studies Unit (HPI-CESU) Technical Reports. The collection represents reports from 1974 to the present.

News

The Pacific Cooperative Studies Unit
& The Hawaii-Pacific Islands cooperative
Ecosystems Studies Unit
University of Hawaii at Manoa
3190 Maile Way
St. John Hall #408
Honolulu, HI 96822-2279

Browse

Now showing 1 - 20 of 215

Assessment of the Performance and Efficacy of the AT220 Trap at Haleakalā National Park
(2024-09) Kayla Purdy, Huisheng Chen, Raina Kaholoaa, Kristian Passaro; Purdy, Kayla; Chen, Huisheng; Kaholoaa, Raina; Passaro, Kristian
Predator control is an ongoing and necessary management tool used to protect native Hawaiian birds at Haleakalā National Park. Since 2017, adaptive management principles have been used to test and integrate new lethal trapping tools as they become available. This project assessed the trapping performance and efficacy of the New Zealand Autotraps AT220 self-resetting, self-rebaiting trap. The AT220 traps were mounted at either a 45° or 90° angle for testing. The traps were baited with the AT220 factory formula or modified custom baits that were created in-house. Wildlife cameras were paired with armed and unarmed AT220 traps to assess species interactions throughout the study. Captures of each predator species was recorded to determine trap efficacy which was calculated using catch per unit effort (CPUE). The significant difference for capture efficacy between trap type by predator species was calculated using a two-sample proportion test on R (version 4.4.1). This study was conducted in two phases. Capture rates for Phase One compared AT220 and DOC 250 traps that were in similar areas. During Phase One, CPUE for AT220 traps was 28.01 for rats, 2.44 for mongoose, and 1.21 for mice compared to DOC 250 traps that showed a CPUE of 54.3 for rats, 4.59 for mongoose, and 6.09 for mice. When determining if capture efficacy was significantly different between DOC 250 and AT220s, capture rates for rats showed a significant difference (p < 0.05) while mongoose and mice capture rates showed no significant difference (p > 0.05). AT220 traps were modified after Phase One to address trap malfunctions. Capture rates for Phase Two compared the modified AT220s to Timms traps located in similar areas. During Phase Two, CPUE for AT220s was 166.67 for mongooses compared to Timms traps that showed a CPUE of 1047.62 for mongoose and 95.24 for feral cats. When determining if capture efficacy was significantly different between Timms and AT220s, mongoose capture rates showed a significant difference (p < 0.05). No proportion test was calculated to compare significant difference for cats since the AT220 capture rate was zero. Both the DOC 250 and Timms traps outperformed the AT220 during this study, though one significant disadvantage to these traps is that they need to be manually reset after each capture. Although the AT220 showed potential for capturing rats, mice and mongoose, several mechanical flaws and difficulties may hamper productivity. This study suggests that until improvements are made to the AT220, incorporating them into the Haleakalā National Park predator control program on a large scale would not be beneficial at this time.
An Overview of the Status and Protection of Maui’s Watershed Forests
(2024-09) Medeiros, Arthur C.; von Allmen, Erica
Today and likely into the future, pure freshwater resources are one of Maui’s greatest gifts and greatest needs, an essential element to existing ways of life, the island’s economy, and a requirement if we are ever to achieve food independence. Though often unrecognized in this role, native watersheds provide one of Maui’s most important natural resources, essential for life as we now know it. The watershed forests of windward exposures of Maui that receive the bulk of the island’s precipitation are still functionally intact over great expanses, retaining their multi-layered, largely native tree and fern dominated forest systems. Because of this, despite the fact that Maui’s native watershed forests have been greatly modified and reduced, windward forests above 3,000 feet to tree line remain fundamentally intact and functionally vital for water extraction purposes. Despite this relatively apparent state of richness currently found in these windward forests, there are factors in motion which appear to threaten the status of this critical natural capitol resource for future generations. Given the current status of Maui’s watersheds and their management, the best-case scenario for windward forests is to maintain a type of ecological stability as time progresses. The unusual and near complete dominance of windward Hawaiian watershed forests by a single tree species, ‘ōhi‘a lehua (Metrosideros polymorpha), creates ecological vulnerability for rapid and dramatic changes to forest structure if the health of that dominant tree species is threatened. Other factors that threaten this forest type are climate change and invasive species. Climate change predictions for Hawaiʻi forecast decreasing precipitation, increasing heat, and greater number and frequency of drought and storm events. Invasive species are non-native species of plant, animal, and pathogen deliberately or incidentally introduced to a new region. A recent dramatic example of pathogen impact on Hawaiian watershed forests was the recent emergence of two Metrosideros-specific pathogenic fungi, collectively known as Rapid ‘Ōhi‘a Death. Decline of the dominant tree species of Hawaiian watersheds, ‘ōhi‘a lehua, would likely trigger successional changes involving the explosive spread of invasive plant species responding to an increase in light and resource availability. Potentially these changes could initiate a cascade of ecological processes that would challenge the long-term stability of watershed forests and water extraction and cause fundamental changes in the ways future generations conduct our lives and manage limited water supplies The degradation and potential loss of native Hawaiian watershed forests is an excellent example of the ‘tragedy of the commons.’ Originally an economic theory, ‘tragedy of the commons’ describes how highly valued community resources can be degraded or even lost because, without direct ownership, no one entity appears to have singular responsibility for the resources’ fate. Studying the interaction of people and ecosystems, Elinor Ostrom, Stanford University, demonstrated that if appropriate systems are instituted, valuable community resources can, in contrast, be responsibly managed and utilized by stakeholders, as well as play a key role in protecting and perpetuating these resources. The community- and partner-based protection and restoration of Maui County’s watershed forests has the potential to be hailed as a classic example of ‘restoration of the commons’, where, with community awareness and support, public and private groups work together to cooperatively provide stewardship for an invaluable community asset. On Maui, watershed forest degradation accelerated dramatically after European contact, approximately 250 years ago, with the introduction of non-native animals and plants. On leeward slopes, wildfires and feral cattle herds were the primary drivers for the near-complete loss of watershed forests on the islands of Maui, Molokaʻi, Lānaʻi, and Kahoʻolawe. From 1790 to 1850, native forests which formerly occurred from near sea level to tree line on leeward exposures were decimated and replaced largely by suites of African, Australian, and Central and South American plant species. Upper elevation native windward ‘ōhi‘a lehua (Metrosideros polymorpha) forests, where most potable water gathering systems are based, receive the bulk of tradewind-associated precipitation in Maui County. Worldwide, native forests, with their diverse, multi-layered canopies and understories, are the most efficient natural systems in processing, filtering, and storing precipitation. Methods to protect Hawaiian windward watershed forests were developed in the 1980s and have remained the primary standard practices for today’s watershed managers. Sadly, despite this, even priority watershed areas are progressively being degraded (especially up to moderately high elevations, ca. 4,500 feet (1,370 m) by landscape-level plant invasions. Conversion of native forests to non-native forests decreases overall aquifer recharge and has reduced ability to manage sediment and sheet flow during torrential rain events. Rapid ‘Ōhi‘a Death (ROD) likely constitutes the worst invasive pathogen threat ever encountered by Hawaiian watershed forests. This assessment is partially regarding the importance of ‘ōhi‘a lehua making up 80% of the trees in our watershed forests, and partially on the impact of ROD, killing over an estimated one million ‘ōhi‘a lehua trees over a four-year period (2017-2021), largely on Hawaiʻi Island. In addition to Rapid ‘Ōhi‘a Death, two other drivers, invasive species and climate change, also threaten to upset the status quo of native windward forests of Maui County and potentially reduce water quantity and quality. Prior to the arrival of humans, the Hawaiian Islands received a new plant species about once every 30,000 years. Since humans first arrived, 20,000-30,000 non-native plant species have been introduced to the islands. Currently, a new non-native plant species arrives about every five days. Without rigorous quarantine measures, threats from new species continue to mount. Despite the fact that they are among the most intact of remaining native Hawaiian ecosystems, windward ‘ōhi‘a lehua forests are vulnerable to large-scale displacement by certain notoriously invasive tropical plant species. Plant invasions at this scale cause drastic changes in species composition and reduced resistance to natural and climatic disturbances, as well as alterations to nutrient, carbon, and water cycles. With yet uncertain implications, climate change is an additional stressor of Hawaiian watershed forests, both independently as well as synergistically interacting with other stressors like diseases and invasive plants.
Aerial biolarvicide application for mosquito control in endangered forest bird habitats on Maui and Kauaʻi
(2024-09) Zhao, Serena; Webber, Bryn; Seidl, Christa; Carnes, Corrina; Doyle, Carolyn; Dautreppe, Nicole; Dyson, Emma; Navarette, Laura; Takakura, Kayla; Cabrera, Allison; Alexander, Jackson; Soalt, Talia; Hollenberg, Mareyna Kai; Krieger-Coble, Pearl; Mounce, Hanna; Crampton, Lisa
Hawaiian honeycreepers are currently under grave threat of extinction, due primarily to infection from avian malaria, an introduced mosquito-borne disease. To reduce the burden of avian malaria on honeycreeper populations, it is necessary to suppress populations of the vector mosquito, Culex quinquefasciatus, which was also introduced to Hawaii. Wide-scale application of a mosquito-specific, bacterially-derived biopesticide has been used extensively for mosquito control in residential areas in the US and around the world. In this study, we demonstrate the efficacy of aerial application of a biopesticide (active ingredients Bti and Bs) in controlling populations of mosquitoes in forest bird habitat in Kauaʻi and Maui. This report also discusses operational protocols for adapting this tool to the Hawaiian context. The use of landscape-scale suppression of mosquitoes at the larval stage is an important component of an integrated vector management approach for sustained management of avian malaria in Hawaii.
An assessment of lethal trap performance and efficacy at Haleakala National Park
(2022-06) Kekiwi, Erika; Purdy, Kayla; Kaholoaa, Raina; Natividad Bailey, Cathleen
Control of non-native predators is vital for managing resources at Haleakalā National Park and has been ongoing since the 1970s. A 2016 evaluation of the trapping program suggested incorporating lethal traps to improve capturing predators. A revised Predator Control Management Plan was developed based on this evaluation, including lethal traps. Since lethal traps can catch non-target species, including federally listed threatened and endangered species, evaluating these traps was necessary. This project assessed three lethal traps for performance and efficacy: Goodnature® A24, DOC 250, and Belisle 220 Super X body grip traps. We evaluated the use of exclusionary box designs and careful trap placement to determine if these features would prevent the capture of non-target species. Captures of species for each trap and interactions of target and non-target species with traps were examined to evaluate trap and exclusion device performance. Wildlife cameras paired with all lethal traps showed no interactions or “unacceptable” interactions with traps or trap boxes by native species, including federally listed species. Capture rates from lethal and live traps were compared in similar areas. Of captures from Goodnature traps, 99% were rats, and 1% were mongooses. Of DOC 250 captures, 71% were mongooses, 25% were rats, and 4% were cats. Body grip traps did not capture any animals during the evaluation period but captured one mongoose during the efficacy period. Goodnature traps had the highest capture rate for rats, followed by DOC 250 and cage traps. DOC 250 had the highest capture rates for mongooses, followed by cage traps. Staff noted that although lethal traps require considerable labor for initial setup, lethal traps required much less labor to monitor than live traps and were advantageous in remote areas. This study suggests that incorporating lethal traps could greatly benefit the predator control program at Haleakalā National Park.
Best Management Practices to Protect Endangered and Native Birds at Solar Installations in Hawai`i
(Pacific Cooperative Studies Unit, 2021-11) Penniman, Jay F.; Duffy, David C.
Solar Energy facilities in Hawaiʻi are a growing major source of low carbon emission energy generation as the state strives to reduce emissions of greenhouse gasses to prevent the worst predictions of global climate change. It is incumbent upon developers of these facilities to consider wildlife impacts and take measures to mitigate for them. While the technology is relatively new there are evolving best management practices that should be undertaken. We identify five endangered waterbird species, three listed seabird species, and one raptor of conservation concern, that have been or may be at risk from solar energy generation facilities in Hawaiʻi. In addition, there are migratory species: fifteen waterbirds and seventeen shorebirds that may be vulnerable. We review relevant literature for impacts and consequences of wildlife interactions with solar energy facilities and recommend best management practices to minimize wildlife impacts. Design considerations for minimizing wildlife impacts are identified, and must be implemented and followed by monitoring to identify and quantify downed wildlife incidents and further development of effective mitigation strategies.
Update on the status of the avifauna of Lehua Islet, Hawai'i, including initial response of seabirds to rat eradication
(Pacific Cooperative Studies Unit, 2021-08) Raine, André; Vanderwerf, Eric; Khalsa, Mele; Rothe, Jennifer; Driskill, Scott
Lehua Islet is a small volcanic islet located 1 km north of Ni‘ihau, protected by the State of Hawai‘i as a Seabird Sanctuary because of its large seabird colonies. Between December 2011 and May 2021, data was collected using a variety of methods to provide an update of the islet’s avifauna, with a particular focus on seabirds. In 2017 a rat eradication project was undertaken to remove the Polynesian Rat Rattus exulans and the islet was officially declared rat free on 20 April 2021. This report therefore provides both an update on the status of the avifauna of Lehua and an assessment of the initial impact of the rat eradication project on breeding seabirds. A total of 39 bird species were recorded on Lehua over the study period, including 18 seabird species (9 confirmed breeding). The most numerous breeding seabird was the Wedge-tailed Shearwater Ardenna pacifica, estimated at 22,226 ± 2,981bp. Lehua is therefore an important refuge for this species, which suffers significant predation by cats and dogs across the Main Hawaiian Islands. Several species, particularly burrow-nesting seabirds, responded positively to rat eradication. The most dramatic changes occurred in the Bulwer’s Petrel Bulweria bulwerii breeding population. This species was rarely encountered before eradication, but numbers of burrows located, the percentage of burrows where adults were confirmed breeding and two measures of nest success increased after eradication. Wedge-tailed Shearwaters also responded positively, with Mayfield Nest Success Estimates significantly higher in the three years after rats were eradicated than in the two years before eradication (t=2.37, p=0.02). Conversely, one species - the endangered Band-rumped Storm-petrel Oceanodroma castro - appeared to decline after rat eradication (as measured via call rates on acoustic sensors), although the change was not significant. Rat eradication has been a critical milestone in the conservation of Lehua Islet, and further natural recovery of seabirds can be expected. Future management actions will be key for capitalizing on the early successes of the rat eradication project. These include social attraction of seabirds that have been extirpated from the islet and habitat restoration through invasive plant removal and outplanting of native species. Regular control of the two remaining non-native predators (Barn Owl Tyto alba and Cattle Egret Bubulcus ibis) on the islet by well-trained predator control specialists will also be critical, as Barn Owls could reverse conservation gains and prevent new seabird species from colonizing. Lastly, ensuring a rigorous biosecurity program and monitoring strategy is vital to prevent reinvasion.
2019 Kiwikiu Conservation Translocation Report
(2021-03-15) Warren, Christopher C.; Berthold, Laura K.; Mounce, Hanna L.; Luscomb, Peter; Masuda, Bryce; Berry, Lainie
The U.S. Fish & Wildlife Service (USFWS) Recovery Plan for the kiwikiu (Maui Parrotbill; Pseudonestor xanthophrys) (USFWS 2006) recommended establishing a second population within its historical range to protect the species from catastrophic loss in its small current range. In addition to the inherent threats of a small population and small range size, the current kiwikiu population is located on the windward (northeastern) slope of Haleakalā where they are under threat from severe weather events and frequent rainfall that have been shown to reduce reproductive success. The Kahikinui region of Maui on the leeward (southern) slope of Haleakalā was selected as the site of a new population of kiwikiu. Nakula Natural Area Reserve (NAR) was selected as the first release site to begin establishing the species in the Kahikinui region. The Maui Forest Bird Working Group (MFBWG; hereafter “the working group”) wrote a comprehensive Kiwikiu Reintroduction Plan (MFBWG 2018). After many years of preparation, which included building infrastructure, controlling predators, and reducing mosquito densities in Nakula NAR, 14 kiwikiu were transferred to the site: seven wild birds translocated from Hanawī NAR and seven from a conservation breeding facility managed by San Diego Zoo Global. The birds from the conservation breeding facility and the wild were moved to Nakula NAR in mid-October 2019 and releases were completed a few weeks later. After release, birds were monitored using radio telemetry through November 2019 at which point all birds either had died or disappeared (except for one individual that was transferred back to the conservation breeding facility). Necropsies indicated avian malaria as the primary cause of death for all recovered individuals and little hope remains for the few remaining missing birds at the site. Unexpectedly high densities of mosquitoes were later confirmed within the release site. Further investigation revealed that the translocated wild individuals tested positive for the malaria parasite prior to the move to Nakula NAR. In this report, we discuss the strategies that were employed during the kiwikiu translocation, the outcome of those actions, and the steps moving forward for both future release improvements and recovery strategies for the kiwikiu.
Updated avifauna of Mokuʻaeʻae Rock Islet 2019
(Pacific Cooperative Studies Unit, 2020-04) Raine, André; Rothe, Jennifer; Driskill, Scott
Mokuʻaeʻae Rock Islet, located off the North shore of Kauaʻi is protected as a Hawaiʿi State Seabird Sanctuary. In the late 1970s it was also the site of a cross-fostering project for the endangered Newell’s Shearwater Puffinus newelli. Few avifauna surveys have been undertaken on the islet, with the most recent prior to this report being undertaken by the Kauaʿi Endangered Seabird Recovery Project (KESRP) in 2013 and 2015 respectively. For this study, the islet was surveyed in June and October of both 2018 and 2019. Burrow searches were conducted across the entire islet to obtain breeding population estimates for each species and to assess whether there was any recent sign of Newell’s Shearwater breeding activity. Two Song Meters (Wildlife Acoustics, SM2+) were also deployed each year at the same two locations, with data collected for two months in June and July. Auditory surveys were also conducted in June 2018 for two hours after sunset and one and a half hours before sunrise. A total of 17 bird species was recorded over the course of the two years, consisting of eight seabird species (of which three – Bulwer’s Petrel Bulweria bulwerii, Wedge-tailed Shearwater Ardenna pacifica and Red-tailed Tropicbird Phaethon rubricauda - were confirmed breeding), one native waterfowl species (Nene Branta sandvicensis, which is the first confirmed breeding record on the islet for this species), five migratory species, and three introduced species. As with previous searches of the islet, there was no sign of Newell’s Shearwater breeding activity and only a handful of calls recorded, concurring with previous reports that the cross-fostering project on the islet was not successful. Despite this, the islet remains an important sanctuary for the three seabird species recorded as breeding on the islet during the surveys and remains the only known breeding colony of Bulwer’s Petrel on Kauaˈi. Depredation by the introduced Barn Owl Tyto alba was identified as a significant threat to seabirds breeding on the islet. Future management actions are suggested to improve the islet for breeding seabirds.
Evaluating the risk of avian disease in reintroducing the endangered Kiwikiu (Maui Parrotbill: Pseudonestor xanthophrys) to Nakula NAR, Maui, Hawai‘i
(Pacific Cooperative Studies Unit, 2019-03) Warren, Christopher; Berthold, Laura; Mounce, Hanna; Foster, Jeffrey; Sackett, Loren
Avian malaria and other introduced diseases have had profound negative effects on Hawaiian honeycreepers, contributing to numerous extinctions and severely limiting the ranges of the remaining species. These diseases, concordant with habitat loss, are thought to restrict many species to narrow ranges at high elevations where cooler climates restrict reproduction of both the malaria parasite, Plasmodium relictum, and its mosquito vector, Culex quinquefasciatus. The Kiwikiu (Maui Parrotbill, Pseudonestor xanthophrys) is a critically endangered honeycreeper that formerly existed throughout Maui and Moloka‘i but now occupies roughly 30 km2 above 1400 m above sea level (asl) on the windward slopes of Haleakalā volcano. The species is thought to be highly susceptible to avian malaria based on its limited range and reported mortality in related species. The primary conservation action proposed for Kiwikiu is to expand the species’ range by reintroducing Kiwikiu to high elevation native forests on the south-facing leeward slope of Haleakalā. As part of an assessment of the suitability of the proposed release site, Nakula Natural Area Reserve, we sought to evaluate the risk of avian disease (i.e., avian malaria and pox) to the future Kiwikiu population. To do this, we trapped adult mosquitoes and surveyed for larvae throughout the release area in 2015–2016. We also tested blood samples from common bird species in Nakula using quantitative polymerase chain reaction analyses to estimate disease prevalence within the current bird population at the release site. To compare disease prevalence to habitat currently occupied by Kiwikiu, we also trapped mosquitoes and tested avian blood samples from common species in The Nature Conservancy’s Waikamoi Preserve in 2016. Unexpectedly, we captured adult and larval C. quinquefasciatus at much higher rates in Nakula than those reported from similar locations at comparable elevations (1530-1620 m asl) throughout Hawai‘i but did not capture C. quinquefasciatus in Waikamoi (1675-1700 m asl). Although leeward slopes receive far less rainfall than windward slopes, the drainages in Nakula contain small pools of water that can provide suitable breeding habitat for the mosquitoes. The frequency of high-flow periods in streams in Waikamoi may regularly “flush out” pools, reducing larval habitat. In contrast, the warmer temperatures and long periods between high-flow events may allow mosquitoes to persist year-round in Nakula. In contrast to mosquito capture rates, analysis of blood samples revealed similar or lower rates of avian malaria in two common honeycreeper species in Nakula compared to similar sites. We also found several individuals of two common honeycreeper species (i.e. Hawaiʻi ʻAmakihi [Chlorodrepanis virens] and ʻIʻiwi [Drepanis coccinea]) captured above 1900 m asl in Waikamoi to be positive for avian malaria. These results suggest that 1) although the persistence of mosquitoes represents an increased risk of infection in Nakula, the Plasmodium parasite may still be physiologically limited by environmental conditions at the release site, 2) the management of mosquitoes (e.g. biopesticides) is advisable to reduce infection risk, and 3) Kiwikiu may be at higher risk in its current range than previously considered. While creating a second population of Kiwikiu in Nakula is critical to safeguarding this species from extinction, mitigating the threat of avian malaria on a larger scale will be the only way to achieve island-wide recovery.
Experimental restoration trials in Nakula Natural Area Reserve in preparation for reintroduction of Kiwikiu (Pseudonestor xanthophrys)
(Pacific Cooperative Studies Unit, 2019-01) Warren, Christopher; Mounce, Hanna; Berthold, Laura; Farmer, Chris; Leonard, David; Duvall, Fern
The native montane mesic forest in the Kahikinui region of Maui, Hawai‘i USA has been degraded by non-native ungulates for over a century. This has resulted in large areas of non-native grassland and savanna with small intact native forest patches, mainly in steep gulches. The Nakula Natural Area Reserve (NAR), on the southwestern slope of Haleakalā volcano, was selected as the site of the reintroduction of Kiwikiu (Pseudonestor xanthophrys), a critically endangered songbird currently found only in a small range on the northern slope of the volcano. This area was selected for the reintroduction because it is located within a mesic koa (Acacia koa) forest representing some of the best potential habitat outside of the current Kiwikiu range. Historic accounts noted the Kiwikiu’s affinity for koa as a foraging substrate, although little koa forest remains on Maui. Intensive forest restoration has created new habitat and enhanced the existing habitat in Nakula to the point where the reserve may now be capable of supporting a small population of Kiwikiu and other native birds. As a precursor to reintroduction efforts, we designed experimental trials to inform managers of the most efficient and effective techniques to restore the forest in Nakula NAR and surrounding region. Trial plots were established in open grass-dominated areas within a fenced, ungulate-free portion of the reserve to investigate natural regeneration, outplanting, and seed broadcast as restoration techniques under a number of conditions. Treatments to suppress and/or remove non-native grass were implemented as these grasses likely reduce germination of native seedlings and potentially influence outplanting success. Some plots were treated with herbicide and the dead grass biomass was removed to expose bare topsoil in a subset of these plots. Additional plots were established under mature koa trees to investigate natural recruitment and the success of these same restoration techniques in this microhabitat. In two years, natural regeneration was largely limited to ‘a‘ali‘i (Dodonea viscosa) and koa, and was enhanced by the application of herbicide followed by the removal of the grass biomass. Outplanting survivorship was high in most species, exceeding 80% after two years in five of seven species. Treatment application had little effect on survivorship, but the growth rates in four of the seven species planted was greatest in plots where herbicide was applied prior to planting. Seed broadcast was not found to be an effective treatment of producing seedlings. Based on our results, we recommend non-native grass biomass removal combined with outplanting as the primary method of forest restoration in Nakula NAR and the surrounding region.
The Nihoku Ecosystem Restoration Project: A case study in predator exclusion fencing, ecosystem restoration, and seabird translocation
(Pacific Cooperative Studies Unit, 2018-09) Young, Lindsay C.; Behnke, Jessica H.; Vanderwerf, Eric A.; Raine, André F.; Mitchell, Christen; Kohley, C. Robert; Dalton, Megan; Mitchell, Michael; Tonneson, Heather; DeMotta, Mike; Wallace, George; Nevins, Hannah; Hall, C. Scott; Kim, Uyehara
Newell’s Shearwater (Puffinus auricularis newelli; NESH) and Hawaiian Petrel (Pterodroma sandwichensis; HAPE) are both listed under the Endangered Species Act of 1973 and are declining due to collisions with power lines and structures, light attraction, predation by feral cats, pigs, rats, and introduced Barn Owls, habitat degradation by feral ungulates (pigs, goats) and invasive exotic plants. Protection of NESH and HAPE on their nesting grounds and reduction of collision and lighting hazards are high priority recovery actions for these species. Given the challenges in protecting nesting birds in their rugged montane habitats, it has long been desirable to also create breeding colonies of both species in more accessible locations that offer a higher level of protection. Translocation of birds to breeding sites within predator exclusion fences was ranked as priority 1 in the interagency 5-year Action Plan for Newell’s Shearwater and Hawaiian Petrel. In 2012, funding became available through several programs to undertake this action at Kilauea Point National Wildlife Refuge (KPNWR), which is home to one of the largest seabird colonies in the main Hawaiian Islands. The project was named the “Nihoku Ecosystem Restoration Project” after the area on the Refuge where the placement of the future colony was planned. The Nihoku Ecosystem Restoration Project is a result of a large partnership between multiple government agencies and non-profit groups who have come together to help preserve the native species of Hawaii. There were four stages to this multi-faceted project: permitting and biological monitoring, fence construction, restoration and predator eradication, followed by translocation of the birds to the newly secured habitat. The translocation component is expected to last five years and involve up to 90 individuals each of NESH and HAPE. Prior to fence construction, baseline monitoring data were collected in order to provide a record of initial site conditions and species diversity. Surveys were conducted quarterly from 2012-2014, investigating diversity and richness of plant, invertebrate, mammalian, and avian species. A 650 m (2130 ft) long predator proof fence was completed at Nihoku in September 2014, enclosing 2.5 ha (6.2 ac), and all mammalian predators were eradicated by March 2015. From 2015-2017, approximately 40% of the fenced area (~1 ha) was cleared of non-native vegetation using heavy machinery and herbicide application. A water catchment and irrigation system was installed, and over 18,000 native plants representing 37 native species were outplanted in the restoration area. The plant species selected are low-in-stature, making burrow excavation easier for seabirds while simultaneously providing forage for Nene (Branta sandvicensis). Habitat restoration was done in phases (10-15% of the project per year) and will be continued until the majority of the area has been restored. In addition to habitat restoration, 50 artificial burrows were installed in the restoration to facilitate translocation activities. From 2012-2017 potential source colonies of NESH and HAPE were located by the Kauai Endangered Seabird Recovery Project (KESRP) with visual, auditory, and ground searching methods at locations around Kauai. The sites that were selected as source colonies for both species were Upper Limahuli Preserve (owned by the National Tropical Botanical Garden; NTBG) and several sites within the Hono o Na Pali Natural Area Reserve system. These sites had high call rates, high burrow densities to provide an adequate source of chicks for the translocation, and had active predator control operations in place to offset any potential impacts of the monitoring. Translocation protocols were developed based on previous methods developed in New Zealand; on the ground training was done by the translocation team by visiting active projects in New Zealand. In year one, 10 HAPE and eight NESH were translocated, and the goal is to translocate up to 20 in subsequent years for a cohort size of 90 birds of each species over a five year period. Post-translocation monitoring has been initiated to gauge the level of success, and social attraction has been implemented in an attempt to attract adults to the area. It is anticipated that the chicks raised during this project will return to breed at Nihoku when they are 65-6 years old; for the first cohort released in 2015 this would be starting in 2020. Once this occurs, Nihoku will be the first predator-free breeding area of both species in Hawaii.
A report on the guano-producing birds of Peru (“Informe sobre Aves Guaneras”)
(Pacific Cooperative Studies Unit, 2018-07) Vogt, William; Dufffy, David Cameron
(Modified from the original) Vogt studied the Guanay Cormorant (Phalacrocorax bougainvillii), Peruvian Booby (Sula variegata), and Peruvian Pelican (Pelecanus thagus) for almost three years (1938 - 1940). The nesting range of these species extends from 04035'S to 380S, covering an area of considerable geographical diversity. The climate is briefly described. The report contains details of the oceanography and marine biology of a part of the nesting range of the birds, and a rejection of the theory that a warm southward-flowing surface current causes major changes on climate and breeding season for guano birds. The histories of past abnormal years and their effects on the birds are reported. The average density of Guanay Cormorant nests is 313.9 ± 3.76 per 100 m2. The ecological efficiency of the islands and their microclimates are linked. The Guanay Cormorant is limited to nesting on the windy parts of the island, which are the coolest, as there is an inverse relation between wind and temperature. A detailed description of the social behavior of the Guanay Cormorant, including its feeding and nesting, is given. Nesting is concentrated in spring and summer. The breeding season keeps the adults on the island for four months every year. The average Guanay Cormorant clutch size is 3.13 ± 0.101 eggs and incubation lasts 27 days. Nesting in large colonies protects nests because fewer birds are at the edges in larger colonies. Various causes of mortality are described. The only significant predator of the Guanay Cormorant may be the Andean Condor (Vultur gryphus). Food is probably the most important limiting factor for the birds. There is a correlation between the abundance of food for birds and the abundance of diatoms. Each Guanay Cormorant eats approximately 215 g/day of food and no more than 316 g/day. Annually, each Guanay Cormorant eats 78.4 to 115.4 kg/year of the Peruvian Anchoveta (Engraulis ringens) and produces approximately 15.8 kg of guano per year. The quantity of fish consumed by birds in the year prior to the guano harvest of 1940 was between 711,903 and 917,150 metric tons. Based on extensive data, this is much lower than previous estimates. Each ton of guano is the result of 4.95 - 7.3 tons of fish consumed, but the guano that the company removes from the islands is only a small proportion of the guano that the birds deposit at sea, where it may act as an important fertilizer for plankton. Preliminary studies suggest that anchoveta are migratory. I have rejected, because of a lack of supporting data, the theory that anchoveta are still present during food shortages, but at depths too great for them to be taken by birds. A preliminary study of 1,427 anchoveta indicated a marked reduction in the year-classes hatched in the spring and summer of 1939 and 1940, when the birds died of hunger. Anchoveta spawned in 1938 were the most abundant. The Peruvian Anchoveta appears similar in biology to the California Sardine (Sardinops sagax caerulea). The commercial anchoveta fishery should be carefully monitored as it represents one of the most serious potential threats to the guano industry. Various interactions of the birds and humans are discussed. I review the history of the guano birds, based on available data, from the pre-Columbian period to the present. The ecologies of the Peruvian Booby and Peruvian Pelican are discussed. Each species seems to occupy a distinct niche so that, within broad limits, the three do not compete with one another. Interactions or the synecology of plants and animals connected with the guano birds appear to be so complex that they require more thorough study. Various management methods are suggested that might allow an increase in the numbers of birds and the proportion of guano harvested. Various management methods are suggested that might allow an increase in the numbers of birds and the proportion of guano harvested.
Post-implementation assessment of novel rodent control devices for protection of high elevation endangered species at Hawai`i Volcanoes National Park
(Pacific Cooperative Studies Unit, 2017-12) Coad, Heather; McDaniel, Sierra; Misajon, Kathleen; Forbes-Perry, Charlotte
Invasive species, including rats, threaten the existence of many of Hawai`i’s native species pushing them to the brink of extinction. Hawai`i Volcanoes National Park has a long history of successfully managing ecosystems and providing rare species habitat through systematic invasive species control. Landscape level rodent control is prohibitively expensive; however, localized control has proven cost-effective while providing significant resource benefit. A trapping program using self-resetting Goodnature® A24 technology was implemented at two remote sites in Hawai`i Volcanoes National Park in an effort to protect five endangered plant species and three endangered bird species from black rat (Rattus rattus) predation. This trapping method has been successfully implemented on other islands, but implementation requirements are site specific. Techniques and maintenance schedules were investigated specifically for subalpine dry shrubland environments and also high elevation wet forest environments. Trap performance, recommended grid spacing, and a new chocolate long-life lure formula were evaluated over the course of this investigation. Apparent rodent control trends and subsequent native species responses were captured over the course of four months by conducting biweekly trap visits and analyzing motion triggered camera footage. Clear declines in rodent activity were documented at each site during the four month intensive monitoring period. At least 38 rodents were removed from the subalpine dry shrubland test site during this period, while at the high elevation wet forest site at least 102 rodents were removed. It is suspected that the number of total kills was underestimated using available monitoring techniques. Trapping activity appeared to prevent major damage to flowers and diminish damage to fruit of endangered Campanulaceae species at the forested test site, however it is unclear what effect trapping efforts had on native bird species at the subalpine shrubland site. Management recommendations differ by site. For subalpine shrubland sites, trap spacing should not exceed 100m x 100m to control M. musculus or R. rattus; tighter spacing may be necessary. In high elevation wet forests spacing traps at 50m x 50m is recommended to effectively reduce R. rattus populations. Pre-baiting traps is not advised to minimize potential damage done by rodents gnawing on depressurized traps. Concurrent trapping for feral cats and other scavengers, or strategic trapping schedules, are recommended to mitigate potential secondary predator attraction for sensitive sites such as Hawaiian petrel nesting areas. Schedule of trap maintenance should include monthly lure checks and ‘refreshment’ squeezes, regardless of site ecosystem. Scent of the lure diminishes between refreshment visits in arid environments and may be masked by algae or mold in wet environments. Use of the Goodnature® automatic lure pump should be considered to potentially alleviate this issue. In both environments standard lure bottles were found to last through the 16 week monitoring period. Lure was found to remain attractive to rodents, after refreshment squeezes as long as 36 weeks after deployment at the forested site. Trap maintenance should be scheduled to check CO2 status no later than 12 weeks after deployment, regardless of site ecosystem, to detect exhausted CO2 or malfunctioning traps, and at monthly maintenance visits if possible. Use of a surrogate pest such as a rubber rat to test fire through the trap shroud is advised to accurately simulate a strike, and ensure functionality of digital strike
Constructing a Predator Exclusionary Fence to Protect Hawaiian Petrels (Pterodroma sandwichensis) at Hawai῾i Volcanoes National Park
(The Pacific Cooperative Studies Unit, 2019-03) Misajon, Kathleen; Hu, Darcy; Medieros, Keola; Forbes Perry, Charlotte; Faford, Jon; Aiona, Fred
Remnant nesting colonies of endangered Hawaiian Petrels, or ‘Ua’u (Pterodroma sandwichensis), on Mauna Loa, Hawai’i Island, are primarily threatened by feral cats. At Hawai῾i Volcanoes National Park, trapping success has been variable due several challenges, including the difficulty of accessing remote, subalpine (9,000’) sites. To create a core area free from cat predation, the park, with support from multiple partners, constructed a five mile barrier fence encircling 640 acres of the richest known concentration of subalpine Hawaiian Petrel nests on Mauna Loa. We report on key fence design elements, pilot studies, step by step construction details, concurrent and subsequent monitoring, and lessons learned throughout the project for the benefit of other managers considering exclusionary fencing.
The Nihoku Ecosystem Restoration Project: A case study in predator exclusion fencing, ecosystem restoration, and seabird translocation
(Pacific Cooperative Studies Unit, 2018-09) Young, Lindsay C.; Behnke, Jessica H.; Vanderwerf, Eric A.; Raine, André F.; Mitchell, Christen; Kohley, C. Robert; Dalton, Megan; Mitchell, Michael; Tonneson, Heather; DeMotta, Mike; Wallace, George; Nevins, Hannah; Hall, C. Scott; Uyehara, Kim
Newell’s Shearwater (Puffinus auricularis newelli; NESH) and Hawaiian Petrel (Pterodroma sandwichensis; HAPE) are both listed under the Endangered Species Act of 1973 and are declining due to collisions with power lines and structures, light attraction, predation by feral cats, pigs, rats, and introduced Barn Owls, habitat degradation by feral ungulates (pigs, goats) and invasive exotic plants. Protection of NESH and HAPE on their nesting grounds and reduction of collision and lighting hazards are high priority recovery actions for these species. Given the challenges in protecting nesting birds in their rugged montane habitats, it has long been desirable to also create breeding colonies of both species in more accessible locations that offer a higher level of protection. Translocation of birds to breeding sites within predator exclusion fences was ranked as priority 1 in the interagency 5‐year Action Plan for Newell’s Shearwater and Hawaiian Petrel. In 2012, funding became available through several programs to undertake this action at Kīlauea Point National Wildlife Refuge (KPNWR), which is home to one of the largest seabird colonies in the main Hawaiian Islands. The project was named the “Nihoku Ecosystem Restoration Project” after the area on the Refuge where the placement of the future colony was planned. The Nihoku Ecosystem Restoration Project is a result of a large partnership between multiple government agencies and non‐profit groups who have come together to help preserve the native species of Hawaiʻi. There were four stages to this multi‐faceted project: permitting and biological monitoring, fence construction, restoration and predator eradication, followed by translocation of the birds to the newly secured habitat. The translocation component is expected to last five years and involve up to 90 individuals each of NESH and HAPE. Prior to fence construction, baseline monitoring data were collected in order to provide a record of initial site conditions and species diversity. Surveys were conducted quarterly from 2012‐2014, investigating diversity and richness of plant, invertebrate, mammalian, and avian species. A 650 m (2130 ft) long predator proof fence was completed at Nihoku in September 2014, enclosing 2.5 ha (6.2 ac), and all mammalian predators were eradicated by March 2015. From 2015‐2017, approximately 40% of the fenced area (~1 ha) was cleared of non‐native vegetation using heavy machinery and herbicide application. A water catchment and irrigation system was installed, and over 18,000 native plants representing 37 native species were outplanted in the restoration area. The plant species selected are low‐in‐stature, making burrow excavation easier for seabirds while simultaneously providing forage for Nēnē (Branta sandvicensis). Habitat restoration was done in phases (10‐15% of the project per year) and will be continued until the majority of the area has been restored. In addition to habitat restoration, 50 artificial burrows were installed in the restoration to facilitate translocation activities. From 2012‐2017 potential source colonies of NESH and HAPE were located by the Kauaʻi Endangered Seabird Recovery Project (KESRP) with visual, auditory, and ground searching methods at locations around Kauaʻi. The sites that were selected as source colonies for both species were Upper Limahuli Preserve (owned by the National Tropical Botanical Garden; NTBG) and several sites within the Hono o Nā Pali Natural Area Reserve system. These sites had high call rates, high burrow densities to provide an adequate source of chicks for the translocation, and had active predator control operations in place to offset any potential impacts of the monitoring. Translocation protocols were developed based on previous methods developed in New Zealand; on the ground training was done by the translocation team by visiting active projects in New Zealand. In year one, 10 HAPE and eight NESH were translocated, and the goal is to translocate up to 20 in subsequent years for a cohort size of 90 birds of each species over a five year period. Post‐translocation monitoring has been initiated to gauge the level of success, and social attraction has been implemented in an attempt to attract adults to the area. It is anticipated that the chicks raised during this project will return to breed at Nihoku when they are 65‐6 years old; for the first cohort released in 2015 this would be starting in 2020. Once this occurs, Nihoku will be the first predator‐free breeding area of both species in Hawaiʻi.
A report on the guano-producing birds of Peru (“Informe sobre Aves Guaneras”)
(2018-07) Vogt, William; Duffy, David Cameron
(Modified from the original) Vogt studied the Guanay Cormorant (Phalacrocorax bougainvillii), Peruvian Booby (Sula variegata), and Peruvian Pelican (Pelecanus thagus) for almost three years (1938 - 1940). The nesting range of these species extends from 04035'S to 380S, covering an area of considerable geographical diversity. The climate is briefly described. The report contains details of the oceanography and marine biology of a part of the nesting range of the birds, and a rejection of the theory that a warm southward-flowing surface current causes major changes on climate and breeding season for guano birds. The histories of past abnormal years and their effects on the birds are reported. The average density of Guanay Cormorant nests is 313.9 ± 3.76 per 100 m2. The ecological efficiency of the islands and their microclimates are linked. The Guanay Cormorant is limited to nesting on the windy parts of the island, which are the coolest, as there is an inverse relation between wind and temperature. A detailed description of the social behavior of the Guanay Cormorant, including its feeding and nesting, is given. Nesting is concentrated in spring and summer. The breeding season keeps the adults on the island for four months every year. The average Guanay Cormorant clutch size is 3.13 ± 0.101 eggs and incubation lasts 27 days. Nesting in large colonies protects nests because fewer birds are at the edges in larger colonies. Various causes of mortality are described. The only significant predator of the Guanay Cormorant may be the Andean Condor (Vultur gryphus). Food is probably the most important limiting factor for the birds. There is a correlation between the abundance of food for birds and the abundance of diatoms. Each Guanay Cormorant eats approximately 215 g/day of food and no more than 316 g/day. Annually, each Guanay Cormorant eats 78.4 to 115.4 kg/year of the Peruvian Anchoveta (Engraulis ringens) and produces approximately 15.8 kg of guano per year. The quantity of fish consumed by birds in the year prior to the guano harvest of 1940 was between 711,903 and 917,150 metric tons. Based on extensive data, this is much lower than previous estimates. Each ton of guano is the result of 4.95 - 7.3 tons of fish consumed, but the guano that the company removes from the islands is only a small proportion of the guano that the birds deposit at sea, where it may act as an important fertilizer for plankton. Preliminary studies suggest that anchoveta are migratory. I have rejected, because of a lack of supporting data, the theory that anchoveta are still present during food shortages, but at depths too great for them to be taken by birds. A preliminary study of 1,427 anchoveta indicated a marked reduction in the year-classes hatched in the spring and summer of 1939 and 1940, when the birds died of hunger. Anchoveta spawned in 1938 were the most abundant. The Peruvian Anchoveta appears similar in biology to the California Sardine (Sardinops sagax caerulea). The commercial anchoveta fishery should be carefully monitored as it represents one of the most serious potential threats to the guano industry. Various interactions of the birds and humans are discussed. I review the history of the guano birds, based on available data, from the pre-Columbian period to the present. The ecologies of the Peruvian Booby and Peruvian Pelican are discussed. Each species seems to occupy a distinct niche so that, within broad limits, the three do not compete with one another. Interactions or the synecology of plants and animals connected with the guano birds appear to be so complex that they require more thorough study. Various management methods are suggested that might allow an increase in the numbers of birds and the proportion of guano harvested. Various management methods are suggested that might allow an increase in the numbers of birds and the proportion of guano harvested.
Testing native species response to fire – a first step towards building fire resilient native plant communities at Hawai’i Volcanoes National Park
(Pacific Cooperative Studies Unit, University of Hawaii at Manoa, 2009-09-01) Loh, Rhonda; Ainsworth, Alison; D'Antonio, Carla
Wildfires, fueled by fire-adapted alien grasses, result in the loss of native tree and shrub species in the dry and seasonally dry communities of Hawai‘i Volcanoes National Park. Future wildfires and further loss of native plant diversity is expected given the prevalence of alien grasses in the area. Fire-tolerance, defined in this paper as the ability to survive or colonize after fire, was evaluated in seven controlled burns. Seed germination in response to oven heating was tested in laboratory experiments. Fourteen of 19 native species showed some capacity to survive or colonize after fire. Seedlings of eleven species were able to establish from seeds placed in the field prior to or immediately following controlled burns (Argemone glauca, Bidens hawaiensis, Canavalia hawaiiensis, Dodonaea viscosa, Myoporum sandwicense, Osteomeles anthyllidifolia, Santalum paniculatum, Scaevola kilaueae, Sida fallax, Sophora chrysophylla, Sesbania tomentosa). Seven species survived beyond the first year including six that reached reproductive maturity (Argemone glauca, Bidens hawaiensis, Canavalia hawaiiensis, Dodonaea viscosa, Sida fallax, Sophora chrysophylla). Seeds of ten species tested in oven-heating experiments showed either a positive or neutral germination response to mild heating (90 ºC), among these were three species (Myrsine lanaiensis, Rhus sandwicensis, Senna gaudichaudii) not tested in the field. Testing species response to fire is the first step toward building resilient native plant communities in the new fire regime established by alien grasses at HAVO.
A review of invasive plant management in Special Ecological Areas, Hawai‘i Volcanoes National Park, 1984-2007
(Pacific Cooperative Studies Unit at the University of Hawai'i at Mānoa, 2014-03-01) Loh, Rhonda K; Tunison, Timothy; Zimmer, Chris; Mattos, Robert; Benitez, David
In Hawai'i Volcanoes National Park (134,852 ha), management units called Special Ecological Areas (SEAs) were established to control 20+ highly disruptive invasive plant species perceived to be too widespread for parkwide eradication to be feasible. Instead control efforts were focused on excluding target weeds from high value areas. SEAs were prioritized for intensive weed management based largely on their 1) representativeness of a particular ecological zone or rarity of vegetation type, 2) manageability, areas are accessible, relatively intact and the potential for native species recovery is high, 3) species diversity and rare species, and 4) value for research and interpretation. Also important to the SEA concept was its flexibility. So while initial weed control focused on only a handful of the best areas, the number and size of units were expanded as additional resources were made available.Between 1984 and 1986 the first six SEAs and a buffer unit (total area >5,000 ha) were established in wet 'ōhi'a/hapu'u (Metrosideros polymorpha/Cibotium glaucum) forest, mesic koa (Acacia koa) forest, and seasonally dry 'ōhi'a communities (Tunison and Stone 1992). After initial treatment of weeds, crews revisited sites at one to five year return intervals to remove any new weeds that reestablished.Over the next two decades, additional funding was made available to increase the number and size of SEAs. By 2007, 27 SEAs and buffer units covering over 26,720 ha were managed to exclude target weeds. These included several more degraded areas that connected isolated units and served as buffer areas to reduce seed dispersal of weeds into adjacent SEAs that were more intact. Control data of 10 SEAs for which we had the longest data sets were evaluated. Typically, initial control of large numbers of weeds (knockdown phase) was followed by subsequent revisits to keep infestations at low or manageable levels (maintenance phase) in SEAs. This was accompanied by a drop in labor cost as fewer worker days were spent searching and removing individuals from a management area. At the maintenance phase, wet forest SEAs still required intensive foot sweeps to search for plants, and were the most expensive to retreat ($385/ha in 2007). Seasonally dry 'ōhi'a communities that employed a combination of aerial and foot sweeps were the least expensive (<$2/ ha including the cost of helicopter rental). From 1985 to 2007, control efforts in SEAs expanded from 5,045 ha to 26,687 ha, a 500% increase in area. In contrast, annual labor cost spent in the field increased only about 50% (adjusted to 2007 dollars). This translated to a three-fold decrease in labor costs per hectare ($28.96/ ha in 1985 to $8.61/ha in 2007) across all units. Additional cost savings were made by improving the efficiency in search and treatment methods (e.g. aerial spray rig, chemical treatment of kāhili ginger).In summary, long-term maintenance of SEAs was possible when initial weed infestations could be reduced to low levels; subsequent recruitment of new alien weeds was low; and work loads dropped significantly after initial control efforts. Weaknesses of the SEA approach were that follow-up treatment was required indefinitely, weed infestations could increase in surrounding unmanaged areas and reinvasion into units could become unmanageable especially for small SEAs. In the future, managers will be challenged to secure funding to address ongoing weed maintenance; and maximize program effectiveness (e.g. optimizing intervals between follow-up treatments, applying new search and control technology). Developing effective partnerships with the community and adjacent landowners to expand management areas, creating buffer zones that will reduce seed dispersal into SEAs, and reconfiguring or abandoning small or ineffective SEAs are among some of strategies that could assist the long-term sustainability of the SEA approach.
Review of the Lehua Island rat eradication project 2009
(The Pacific Cooperative Studies Unit, 2017-05-01) Parkes, John; Fisher, Penny
The eradication of introduced mammals is a prerequisite for a larger program to restore biodiversity on 126-ha Lehua Island, Hawaii. Rabbits were eradicated by 2006 and an attempt was made to eradicate the remaining species, the Polynesian rat (Rattus exulans), in January 2009. Planning for the eradication of rats began in 2005 and covered legislative, regulatory, environmental risk assessment, operational and contingency response aspects of the project. Aerial application of rodenticide baits, the most commonly used (and sometimes only practical) method to eradicate rodents on large or topographically challenging islands, was chosen as the method for Lehua Island. Two rodenticide baits containing brodifacoum and one containing diphacinone rodenticides are registered for aerial application on islands in the USA. The particular history of rodent control on the larger islands, public sentiment, and the policy climate in Hawaii meant the use of diphacinone was favored for the Lehua project. The use of diphacinone has some major advantages over brodifacoum in eradicating island rodents (and for sustained control when eradication is not feasible) largely because its toxicity and environmental persistence confers lower hazard to non-target wildlife. However, diphacinone does not have such an established operational history as brodifacoum, particularly when baits are broadcast from the air. An analysis of 206 previous eradication attempts against five species of rodents on islands using brodifacoum or diphacinone is presented in an appendix to this report. For all methods, 19.6% of 184 attempts using brodifacoum failed, while 31.8% of 22 attempts using diphacinone failed. This difference is not statistically significant (Fisher’s Exact Test P = 0.26). The two toxins have similar failure rates for ground-based operations (29% for brodifacoum and 23% for diphacinone; Fisher’s Exact Test P = 0.77). The limited evidence suggests aerial baiting using brodifacoum has a lower failure rate (11% of 93 attempts) than for diphacinone (75% but of only 5 attempts) (Fisher’s Exact test P = 0.010). However, we caution against drawing firm conclusions about these differences because of the small sample size for the diphacinone attempts. The attempt to eradicate rats from Lehua Island was therefore a logical step in expanding the ‘track record’ for effective use of diphacinone in eradicating rodents. However, 7 months after two aerial applications of diphacinone bait, Polynesian rats were found on Lehua Island, indicating that the operation had failed – or that rats had reinvaded the island, or both. In early April 2010, the Research Corporation of the University of Hawaii on behalf of the Hawaii Department of Land and Natural Resources contracted Landcare Research to review the Lehua Island rat project. The senior author visited Hawaii between 17 and 21 April 2010 to discuss the project, and followed this with email and telephone dialogue with the aim of providing a draft report for comment by 13 May 2010. This draft report was revised following comments by internal referees and Hawaiian stakeholders.
The Tahiti Petrels Night on Mt. Lata, Ta'u. National Park of American Samoa
(Pacific Cooperative Studies Unit, University of Hawaii at Manoa, 2003-12-01) Rauzon, Mark
The 3000' foot summit of the island of Ta'u is Mt. Lata, a vine and tree fern forest whipped by wind, fog and rain. Two thousand foot cliffs from the south side of the summit to the valley floor below. Before darkness settles in, cicadas pulse a busy-signal before quieting for the night. Fruit bats and wattles honeyeaters are also voices in the forest. After dark, Tahiti petrels, large black and white seabirds, return from feeding at sea and fly around Mt. Lata before landing and visiting their nests under the roots of the dense vegetation. Audubon shearwaters also join the choir of petrel whistles and shrieks. This CD is an aural window into the ancient past when Polynesia was only populated with seabirds, fruit bats and other things that go bump in the night. Recorded in Dec. 2001 and 2002, using a parabolic dish to amplify calls below the cliff. Surf and wind noise have been filtered out so the birds calls can be more readily hear.

Browse

Recent Submissions