Knapp, J.J.; P.T. Schuyler, K.N. Walker, N.L. Macdonald,Island and invasives: S.A. Morrison. Benefieradication ts of supporting andinvasive management plant and animal eradication projects with helicopters Benefits of supporting invasive plant and animal eradication projects with helicopters J. J. Knapp 1, P. T. Schuyler 2, K. N. Walker 1, N. L. Macdonald 1, and S. A. Morrison 3 1Native Range, Inc., 1746-FS. Victoria Avenue, #378, Ventura, California, 93003, USA. <[email protected]>. 2525 Lorraine Ave. Santa Barbara, California, 93110, USA. 3The Nature Conservancy, 201 Mission Street, 4 th Floor, San Francisco, California, 94105, USA. Abstract To eradicate invasive alien species from islands, land managers must have the ability to: detect all individuals, remove all individuals, outpace reproduction, and commit adequate resources to ensure project completion. Any inability to meet these criteria – whether due to technical, fi nancial or political factors – can fate a project to failure. Here, we discuss how helicopter-based methods can increase the likelihood of meeting eradication success criteria, while at the same time increasing effective use of limited resources and enhancing personnel safety. We examine the effi ciency and effectiveness of ground-based and aerial-based eradication methods used to eradicate feral pigs and control a suite of invasive plants to zero density on two islands in southern California, USA: Santa Catalina Island and Santa Cruz Island. This study highlights numerous advantages of using an intensive, systematic aerial approach in eradication efforts, as compared to more traditional ground-based methods. Keywords: Channel Islands, feral pig, Sus scrofa , eradicate, effectiveness, systematic approaches INTRODUCTION Invasive alien species pose a signifi cant and increasing relatively few visitors. Santa Cruz is within the Channel threat to native biota and unique ecosystems of islands Islands National Park (CINP) which owns 24% of the worldwide. Because conservation funding is limited, an island; the remaining 76% is owned and managed by The imperative for managers is to ensure that threats posed by Nature Conservancy (TNC), a non-profi t conservation invasive species are resolved as effi ciently and effectively organisation. Other than a few management staff, there are as possible. Eradication of pest taxa often can be a cost- no permanent residents on Santa Cruz, although the public effective strategy relative to alternatives such as perpetual does have limited hiking and camping opportunities. control. But eradications require managers to meet a number Below, we highlight the similarities and differences of criteria. They must be able to: 1) detect all individuals, between the pest eradication programmes on the two 2) remove all individuals, 3) outpace reproduction, and islands. We do so in the context of the aforementioned 4) commit adequate resources to ensure completion four eradication criteria, and discuss how the systematic (Bomford and O’Brian 1995). If these criteria cannot be use of a small helicopter can help managers meet those met, a project risks failure. Fortunately, managers today criteria. In contrasting the two projects it is important to can review decades of eradication projects. By analysing note the relationship between the two islands. Channel numerous taxa in a variety of island conditions, it is possible Islands land managers regularly share lessons learned from to identify methods that might reduce the risks inherent conservation activities on other islands. The Santa Cruz in eradication efforts, and complete the eradication with feral pig and IAP programmes were thus able to benefi t greatest effi ciency. from the prior experience of the Catalina programmes. The In this paper, we compare and contrast the cost and risks Catalina programmes were infl uenced by invasive species of using aerial-based eradication methods versus more management programmes on other Channel Islands, such traditional, ground-based methods. We do so by examining as feral sheep ( Ovis aries ) and feral goat ( Capra hircus ) eradication efforts focused on the invasive feral pig ( Sus eradications on Santa Cruz and San Clemente islands, scrofa ) and a suite of invasive alien plant (IAP) species on respectively. two of the eight Channel Islands off the coast of southern California, USA (Fig. 1). Santa Cruz Island (Santa Cruz), at 249 km 2 is the largest of the Channel Islands; Santa Catalina Island (Catalina), at 194 km 2, is third largest. Both islands have a Mediterranean-type climate, support similar vegetation communities, and exhibit generally similar topographical relief, although Santa Cruz is more diverse due to its larger size and higher elevation (Schoenherr et al . 1999). Since the 1800s, each island has experienced a history of intensive livestock grazing that has signifi cantly altered the native ecosystems. Neither island has any native ungulates (Schoenherr et al . 1999). Although both islands share many of the same native and alien taxa, there are important differences. Since 1972, the Catalina Island Conservancy (CIC), a non-profi t conservation organisation, has managed 88% of Catalina Island. The remaining 12% is owned by a variety of private land owners. Catalina is the only Channel Island that has an incorporated city (Avalon), with a resident population of approximately 4000 that swells to over 15,000 in the summer months. This has undoubtedly represented a signifi cant challenge to conducting eradications. In addition, the island receives nearly 1.2 million visitors annually (Ann Muscat, CIC President pers. comm.). In Fig. 1 Santa Catalina and Santa Cruz Islands in the contrast, all of Santa Cruz is protected, and the island has Southern California Bight. Pages 188-191 In: Veitch, C. R.; Clout, M. N. and Towns, D. R. (eds.). 2011. Island invasives: eradication and management. IUCN,188 Gland, Switzerland. Knapp et al .: Benefits of aerial methods in eradication Table 1 Comparison of feral pig eradication programmes. Data from Macdonald and Walker (2008), Morrison (2007), and Schuyler et al. (2002). Island area Hunting duration Animals Contractor Expense Project Island (hectares) (years) dispatched (U.S. dollars)* Completed Catalina 19,400 10.0 11,855 $3.2 million No Santa Cruz 24,000 1.1 5036 $3.9 million Yes *See Morrison 2007 for calculations. Fencing costs not included. Adjusted for inflation to 2005 value. FERAL PIG PROGRAMMES of educating pigs to removal methods. This in turn reduced the rate of population replacement and the total number of The attempted eradication of feral pig populations pigs ultimately dispatched (Table 1). A light piston engine on Catalina Island evolved from a control programme three-person, helicopter (Schweizer 300C) was used to that began in 1990 (Schuyler et al . 2002a). Financial support the full array of activities throughout the project: constraints, and uncertainty of some CIC board members from aerial shooting to deploying bait and checking traps, that eradication was achievable, helped to establish control from transporting hunters and dogs to tracking Judas pigs rather than eradication as the initial goal (Schuyler et al . and monitoring (Macdonald and Walker 2008). 2002a). Methods and strategies were refi ned and adapted as the control programme was underway. Throughout the effort, ground hunting with and without dogs, spotlighting, INVASIVE ALIEN PLANT ERADICATION and trapping were used; helicopters were occasionally used PROGRAMMES to deploy equipment. A helicopter was used as a platform In 2003, following the near eradication of feral pigs for an aerial shooter only occasionally in the early phases of from Catalina, a ground-based island-wide survey for 72 the project and was later abandoned due to public pressure invasive alien plant (IAP) species was commissioned by (Schuyler et al . 2002a). In 1998 the objective was changed the CIC. The survey revealed that several species were to eradication, in part because it had become increasingly ideal candidates for eradication based on their limited apparent that sustained control would not accomplish the abundance and distribution (Knapp in press). In 2004, the desired conservation goal (Schuyler et al . 2002a). Fencing CIC developed a programme to eliminate 25 species of was then erected to subdivide the island and create hunting IAPs from either the CIC property or throughout the island zones. Throughout the programme, if hunters encountered while the infestations were relatively manageable (Knapp multiple pigs they would attempt to dispatch them, even if in press). Similarly, in 2007, following the successful some were likely to escape (Kevin Ryan and Mark Szydlo, completion of the Santa Cruz feral pig eradication Catalina hunters pers. comm.). As is discussed below, this programme, TNC conducted an island-wide IAP survey approach was not used on Santa Cruz. for 55 species of IAPs (McKnight et al . 2007) and selected In contrast to Catalina, on Santa Cruz Island, eradication 18 species for eradication following the same criteria used of pigs was the goal of TNC and CINP from the outset on Catalina (Knapp et al . 2007). The IAP survey on Santa (Morrison 2007). Prior to the beginning of the eradication Cruz was conducted 95% via helicopter and 5% on foot, effort, fenced zones were established across the island. The and covered the entire island (Knapp et al . 2009); this is in project was planned and implemented to ensure that the pig contrast to Catalina, which was surveyed on foot and only populations