Department of Defense Legacy Resource Management Program Project 07-339 Predator-proof Fencing for Invasive Species Control in Hawaii: A Comprehensive Prioritization and Implementation Plan to protect native species Bradford S. Keitt, Island Conservation 31 January 2008 Predator-proof Fencing for Invasive Species Control in Hawaii: A Comprehensive Prioritization and Implementation Plan to protect native species Prepared by: Dr. Eric VanderWerf and Lindsay Young, Pacific Rim Conservation, Honolulu, Hawaii; and Brad Keitt, Island Conservation, Santa Cruz, CA Protecting Native Species in Hawaii with Predator Proof Fencing Island Conservation TABLE OF CONTENTS Executive Summary.........................................................................3 Background......................................................................................4 Prioritization Process and Site Selection .........................................6 Site Visits.........................................................................................9 Implementation Plans for Selected Sites: 1. PTA Solanum incompletum ...........................................11 2. Kahanahaiki ...................................................................16 3. Niulii Ponds ...................................................................23 4. Waieli Bench..................................................................27 Maintenance of Pest Proof Fences.................................................33 Permits and Compliance Documentation.......................................34 Pest Eradication .............................................................................35 Biological Monitoring....................................................................37 Site Specific Monitoring Recommendations .................................46 Cost-Benefit Analysis ....................................................................55 References......................................................................................58 List of Appendices .........................................................................63 Appendix 1: Meeting Minutes .......................................................64 Appendix 2: Site Description Template.........................................70 Appendix 3: Site Descriptions .......................................................71 Appendix 4: Site Ranking Criteria...............................................111 Appendix 5: Site Visit Summaries...............................................115 Appendix 6: Complete Xcluder Reports......................................122 Appendix 7: Response to Army comments .................................132 2 Protecting Native Species in Hawaii with Predator Proof Fencing Island Conservation EXECUTIVE SUMMARY There are over 15 military installations and ranges in Hawaii, and still more on other Pacific islands. Within the over 200,000 acres encompassed by these military lands, there are more than 100 threatened and endangered species representing approximately one third of the total listed species in Hawaii and nearly 10% of all threatened and endangered species in the United States. This creates a challenge for the Department of Defense (DoD) with how to effectively use lands, air, and sea for national security missions while simultaneously conserving species protected by the Endangered Species Act (ESA). On military installations in Hawaii, a range of introduced vertebrate pest species reside in and around many key natural resource areas that DoD is mandated to protect under the ESA. These introduced pests include predators such as rats (Rattus spp.), small Indian mongoose (Herpestes auropunctatus), feral cats (Felis catus), and feral dogs (Canis familiaris), and a variety of ungulates such as feral pigs (Sus scrofa), feral sheep (Ovis aries), feral goats (Capra hircus), and mouflon sheep (Ovis musimon). These alien animals consume and trample endangered native plants and their seeds and prey on endangered birds and snails. Despite control programs on some DoD lands, predation and browsing is still a serious problem in many areas. One way to reduce or eliminate the damage would be to exclude and eradicate pests from key natural resource areas using pest proof fences that exclude all of the above mentioned vertebrate pests. Island Conservation (IC) received funding from the DoD Legacy Resource Management Program, under Cooperative Agreement Number W912DY-07-2-0003, to prioritize sites within Hawaii DoD land holdings that would be candidates for predator proof fencing. The prioritization was done by having each branch of the military nominate their top natural resource sites (13 total) and provide an accompanying site description. A set of ranking criteria that incorporated both biological and feasibility criteria were developed as a group with military personnel, and each site was ranked using these criteria. The top nine sites representing locations managed by all military branches were selected for site visits with IC, consulting biologists, and Xcluder Pest Proof Fencing Company. In August 2007, IC, consulting biologists, and Xcluder Pest Proof Fencing Company visited the top nine selected sites in order to evaluate the feasibility and cost of building a pest proof fence capable of excluding all pests present at each site. Pest proof fencing appeared to be technically challenging, but feasible, in most locations, and suggested fence alignments, construction plans, and budgets were developed by Xcluder for the top four sites. The top four sites were selected based on the feasibility of constructing a successful demonstration fence within budget and the potential biological benefit in addition to the initial ranking criteria. The sites selected were Pohakuloa Training Area (PTA) Solanum incompletum site on the island of Hawaii, and Kahanahaiki and Waieli Bench on Oahu, all of which are owned by the Army, and Niulii Ponds on Oahu which is owned by the Navy. Complete implementation plans for these top priority sites, including pre- and post-fence biological monitoring, eradication, and cost benefit analyses were developed. This exercise offers a valuable opportunity to determine the potential effectiveness of pest proof fencing for protection of threatened and endangered species in a variety of ecosystems in the Hawaiian Islands and can serve as a model for other predator proof fencing exercises. 3 Protecting Native Species in Hawaii with Predator Proof Fencing Island Conservation BACKGROUND Islands make up 1.3% of the U.S. land area yet are home to 43% of ESA listed species and 53% of extinctions. Invasive species are the primary threat to island ecosystems and are responsible for approximately two-thirds of all island extinctions in the past 400 years (Reaser et al 2007). Hawaii not only is the state with the greatest number of threatened, endangered, and extinct species, but also the state with the highest proportion of endemic flora and fauna (Ziegler 2002). Non-native mammals – primarily rats, cats, mongoose, goats, sheep, and pigs – have had devastating impacts on listed and at-risk species and are major factors in population declines and extinctions in Hawaii and elsewhere (Ziegler 2002, Reaser et al 2007). Ungulates have already been excluded from several large tracts of sensitive habitat in Hawaii using fencing. However, these fences do not exclude smaller pest species such as mongooses, cats, and rodents. Impacts of feral cats and mongooses in Hawaii have been well documented, including the predation on many endangered species, primarily birds (Hodges and Nagata 2001, Smith et al. 2002, Laut et al. 2003). Invasive rodents such as rats and mice constitute a potentially even greater threat to native species by contributing to extinctions as well as ecosystem level changes (Fukami et al 2006). In Hawaii, rats have been documented to prey on ground-nesting seabirds, forest birds including the endangered O‘ahu ‘Elepaio and the Laysan finch (VanderWerf and Smith 2002). As omnivorous feeders, rats are also known to eat the seeds, fruits, leaves, and shoots of a variety of plants, including stripping the bark of koa (Acacia koa) saplings and eating the seeds of loulu (Pritchardia spp.) palms and other endangered plant species (U.S. Army 2006, A. Sheils unpubl. data). These actions may kill plants outright, make them more susceptible to pathogens or insects, or prevent natural reproduction. While rats can be controlled in small areas using bait stations and traps, it is extremely labor intensive and not a permanent solution. Until recently, there was no way to effectively eradicate rats and mice from larger islands, or even to exclude them from specific areas. On military installations in Hawaii, a range of introduced vertebrate pest species reside in and around many key natural resource areas that DoD is mandated to protect under the ESA. These introduced pests include predators such as rats (Rattus spp.), small Indian mongoose (Herpestes auropunctatus), feral cats (Felis catus), and feral dogs (Canis familiaris), and a variety of feral ungulates such as feral pigs (Sus scrofa), feral sheep (Ovis aries), feral goats (Capra hircus), and mouflon sheep (Ovis musimon). These alien animals consume endangered native plants and their seeds and prey on endangered birds and snails. Despite control programs on some DoD lands, predation and browsing is still a serious problem. One way to reduce or eliminate the damage would be to exclude and eradicate pests from key natural resource