CHAPTER 3: ACHATINELLA SPECIES MANAGEMENT

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1 CHAPTER 3: ACHATINELLA SPECIES MANAGEMENT 3.1 INTRODUCTION OANRP changed the annual reporting format, therefore, this year s rare snail chapter is very different from previous year-end reports. All the tabular data and ESU updates are achieved this year through a distributed copy of the OANRP database. Please refer to Appendix ES-2 for a tutorial on how to access this data. The annual report from the UH snail lab can also be found in this Appendix (ES-3). That report summarizes captive propagation and Jackson s chameleon study results. This chapter will update OANRP efforts to construct three new rare snail and predator proof enclosures. 3.2 PREDATOR RESISTANT FENCING OANRP embarked on a long awaited project this year, the construction of predator proof fences at three sites; Puu Hapapa and Palikea in the southern Waianae Mountains and Poamoho in the northern Koolau Mountains. The goal for these exclosures is to exclude all predators and provide an area where Achatinella and other rare Hawaiian snails can exist free from rats, mice, Euglandina rosea and Jackson s chameleons. Sites were chosen after careful consideration and site selection criteria included relatively flat terrain, accessibility, and high quality snail habitat. Flat terrain is necessary due to design and budget limitations Makua and Oahu Implementation Plan Status Report 207

2 3.3 PREDATOR RESISTANT EXCLOSURE SITES To begin this project, OANRP requested that interested and qualified companies submit proposals. Only two companies expressed interest in the project; Pest Proof Fencing and Excluder. Both of these companies are based in New Zealand and have a proven track record of constructing this type of fencing. Proposals for the project were accepted in August 2010 and OANRP selected Excluder to build the exclosures given their lower cost. The overall design was based on a rat/mouse proof mesh fence with added barriers for predatory snails. The rat/mouse proof fence needed to be a tested and proven design consisting of a buried ground barrier, a hood, tight-mesh construction, and engineered fasteners and junctions. All fence materials must be stainless steel or heavily galvanized to ensure longevity under harsh conditions. In addition to the typical mouse/rat exclusion features, additional barriers against Euglandina rosea will be mounted to include an angle obstacle barrier, an electric wire barrier, and a cut wire mesh barrier Angle Obstacle Barrier: This is the simplest of the barriers to be installed. A smooth piece of copper or stainless flashing will be attached to the vertical wall of the fence such that it extends down at an angle of and at its terminal edge is at least 7 cm from the wall of the fence. The picture below shows the trial box for tests of this barrier Electric Barrier: Two 16-wire livestock tapes are fastened in parallel to the vertical surface. These tapes are attached to an electric fence unit and will deliver a shock to snails that attempt to cross the wires. The photo below shows the trial box with wire tape in its proposed configuration. So far this configuration has worked fine o a small scale but has proven unsuccessful when expanded into a larger scale. More experimentation will be required before the electrical barrier is finished Makua and Oahu Implementation Plan Status Report 208

3 3.3.3 Cut Wire Mesh Barrier: This is the most effective physical barrier and has no electric components. The barrier works by presenting a surface that does not provide adequate adhesion to snails. E. rosea would need to cross the barrier upside-down and the snails are unable to do this. The points must be spaced close enough to force E. rosea of all sizes to pass over the wire and not through it. There are no strict parameters and Excluder is currently looking into various options for the production of this barrier. Below is a close up of the barrier constructed with copper screen mesh mounted no more than 4-5 mm apart for a total width of no less than 8 cm. 3.4 REMOTE SITE MONITORING OANRP want to maintain these sites with only a minimum number of visits. There will be occasional site visits to conduct necessary resource management activities and record biological data but they will be relatively infrequent. With so much invested in the development and construction of these fences, a remote monitoring system will be included to ensure continuous barrier integrity. This system must be remotely accessible and provide the following information: The system will indicate if anything has fallen across the barrier and a breach has occurred. This can be accomplished by using a grounding ring system or something comparable. It will report the integrity of the photovoltaic system including the condition of the batteries. It will collect weather data including temperature, wind speed, direction and gust velocity, humidity and rain fall. These can be measured by many types of commercially available weather stations Makua and Oahu Implementation Plan Status Report 209

4 It may use remote-access cameras as a useful monitoring device. 3.5 CONSTRUCTION STATUS In the summer of 2011, Excluder crews began construction on the Puu Hapapa and Poamoho fences. The rodent resistant barriers were mostly completed and the Excluder crew is expected to return in November 2011 to build the Palikea exclosure and install the E. rosea barriers and hoods on all three fences. This will take approximately one month to complete. Discussions are continuing about the final configuration of the three barriers presented above. Below are details about each site Puu Hapapa, Waianae Mountains. Near the summit of Puu Hapapa at 2,600 feet, the site is a mix of native and introduced vegetation and is protected from ungulates by large scale fencing. Puu Hapapa is an area of intensive management, with ongoing weed control, outplanting and rare species management. Puu Hapapa has been an area of recent focus by OANRP as the predatory snail E. rosea reached previously undocumented numbers and greatly reduced the large number of A. mustelina in the area in just 6 years. OANRP has been removing E. rosea from the area and moving A. mustelina to the University of Hawaii snail laboratory for safe keeping. See Appendix ES-3 for status of these snails. The pest resistant fence is 170 m long and encompasses approximately one half acre. The terrain is relatively flat and the substrate is mostly soil. Location of the Hapapa Exclosure 2011 Makua and Oahu Implementation Plan Status Report 210

5 Completed Section of the Hapapa Exclosure with Common Native Outplantings 2011 Makua and Oahu Implementation Plan Status Report 211

6 Aerial View of Hapapa Snail Exclosure Poamoho, Koolau Mountains. Near the source of the Helemano stream drainage, at 2,600 ft, a site has been chosen for the reintroduction and translocation of multiple species of endangered Hawaiian tree snails. OANRP will work with four species of Achatinella that occur sympatricly nearby: A. sowerbyana, A. bulimoides, A. lila, and A. byronii/decipiens. The site is not surrounded by ungulate-proof fencing; however it will be enclosed within a larger ungulate fence after construction is complete. This will help to provide a wind screen as well, hopefully increasing its longevity. The area is a mix of short wind-swept native trees and introduced and native understory vegetation. Of special note is the winds often blow in access of 40 mph and not uncommonly reach speeds in excess of 70 mph. The proposed fence line is 175 m long and approximately one half acre in size. The terrain is relatively flat and the substrate is soft, muddy soil. The land here is owned by Kamehameha Schools Bishop Estate and there are no Achatinella snails here at the present time, although they were at this site in Makua and Oahu Implementation Plan Status Report 212

7 Location of the Poamoho Exclosure Pictures of the Construction at Poamoho 2011 Makua and Oahu Implementation Plan Status Report 213

8 2011 Makua and Oahu Implementation Plan Status Report 214

9 The above photo shows wind damage to the wall of the exclosure incurred because the wall was left incomplete and in a weaker state than if construction had been completed Puu Palikea, Waianae Mountains. This site is located at the 3,000 ft level in the Honouliuli Forest Reserve and is a mixture of mesic-wet native and non-native forest (see map below). It is home to A. mustelina as well as the rare Laminella sanguinea snail species and the endangered Drosophila substenoptera fly species. The construction component for the exclosure is being funded by the U.S. Fish and Wildlife Service and OANRP will supply monitoring and management. The area is protected from ungulates by large scale fencing. The proposed fence line is 150 m in length and approximately one fifth acre in size. The terrain is relatively flat and the substrate is mostly soil. Construction of the Palikea exclosure should begin in November Vegetation restoration plans are being developed for each exclosure to encourage maximum native plant cover which maintains a moist environment and supports an appropriate microclimate for Achatinella Makua and Oahu Implementation Plan Status Report 215

10 Location of the Poamoho Exclosure Legend Natural Resource LZs Trails ~ Existing Fence - Snail Exclosure Management Unit o I Meters ~ I N 2011 Makua and Oahu Implementation Plan Status Report 216