Post-implementation assessment of novel rodent control devices for protection of high elevation endangered species at Hawai`i Volcanoes National Park

Reports were scanned in black and white at a resolution of 600 dots per inch and were converted to text using Adobe Paper Capture Plug-in.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 strik

Constructing a Predator Exclusionary Fence to Protect Hawaiian Petrels (Pterodroma sandwichensis) at Hawai῾i Volcanoes National Park

Reports were scanned in black and white at a resolution of 600 dots per inch and were converted to text using Adobe Paper Capture Plug-in.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

Fencing to Protect Hawaiian Petrels from Feral Cats: A Progress Update

On Hawaii Island, within Hawai’i Volcanoes National Park, remnant nesting colonies of Hawaiian petrels, or ‘Ua’u, persisting in subalpine lava flows of Mauna Loa are threatened by feral cats. Trapping has not fully protected these approximately 60 known nests. In some years, cats have killed multiple petrels over the protracted breeding season. To create a core area free from cat predation, the Natural Resources Management Division of Hawai’i Volcanoes National Park, with support from multiple partners, is constructing a 5.5-mile-long barrier fence around the largest known colony. Project planning began in 2009, and fence construction started in 2013. Our design, modified from an Australian fence, is skirted to the substrate at the bottom and rolled over at the top to form a springy, outward-facing arc. Work to date includes finalizing the route, helicoptering in fencing materials and gear to the 9,000+ foot elevation site, pulverizing a narrow work corridor along the fence route (most of it on rough, aa lava), installing approximately 3,900 posts, and attaching visibility marking tape to alert flying petrels. We anticipate needing 1-2 additional work seasons to complete the fence. Ongoing petrel nest monitoring will help us assess response of the colony. Additionally, recently-installed interpretive panels inform park visitors of the conservation needs of this elusive bird

Long-term history of vehicle collisions on the endangered Nēnē (Branta sandvicensis).

Millions of birds in the United States die annually due to vehicle collisions on roads. Collisions may be of particular interest for species of conservation concern, such as the endangered Hawaiian goose (Nēnē), which is endemic to Hawai'i. Using a nearly 40-year dataset of Nēnē road mortality in and around Hawai'i Volcanoes National Park, we sought to answer the following research questions: 1) has Nēnē mortality changed over time? 2) are there times of the year in which mortality is greatest and does it relate to specific events in the species' lifecycle? 3) does age at mortality differ over time, space, or sex? 4) given that existing mortalities appear to occur only in certain locations, do the number of mortality events differ across these locations; 5) does mortality rate show any density dependence? and, 6) are mortality rates related to numbers of visitors or vehicles? Between 1977 and 2014, a total of 92 Nēnē died from vehicle collisions; while absolute mortality increased over this time, the mortality rate remained the same. Similarly, average age of mortality increased over time, but did not differ by location or sex. Between 1995 and 2014, Nēnē population size and mortality rates were not correlated. Mortality was greatest in November and December (breeding season) and lowest in June. Most of the mortality occurred along just three stretches of road in and around the park, with the number of mortalities split about evenly inside and outside of the park. Furthermore, Nēnē mortality was unrelated to the number of visitors or traffic volume in the park. These findings suggest vehicle collisions are a growing concern for Nēnē, but that management actions to reduce mortality can be targeted at specific road segments and times of the year