Baudat-Franceschi, J.; P. Cromarty, C. Golding, S. Cranwell, J. Le Breton, J.P. Butin, and S. Boudjelas. Rodent eradication to protect seabirds in New Caledonia: the importance of baseline biological surveys, feasibility studiesIsland and community invasives: support eradication and management Rodent eradication to protect seabirds in New Caledonia: the importance of baseline biological surveys, feasibility studies and community support J. Baudat-Franceschi1, P. Cromarty2, C. Golding3, S. Cranwell4, J. Le Breton5, J.P. Butin6, and S. Boudjelas7 1Société Calédonienne d’Ornithologie, Antenne Nord. BP 236, 98 822 Poindimié, Nouvelle Calédonie. <julien.bf@sco. asso.nc>. 2Department of Conservation, PO Box 10-420, Wellington. New Zealand. 3Department of Conservation, PO Box 97, Motueka, New Zealand. 4Birdlife International Pacific Secretariat, GPO Box 18332, Suva, Fiji.5 Biodical, 43 rue de l’Alezan, Robinson, 98809 Mont Dore, Nouvelle Calédonie. 6Province Nord, DDEE, Service des Forêts, District de Koné, 98860 Koné, Nouvelle Calédonie. 7Pacific Invasive Initiative, ISSG IUCN, University of Auckland, Private Bag 92019, Auckland, New Zealand. Abstract Eradications of introduced rodents are important for the protection of seabirds. This paper reports on a two- year programme funded by the Packard Foundation to remove exotic rodents from seabird breeding islands in the lagoon of New Caledonia. Although many such islands are close to inhabited areas and heavily used by local communities, rarely has the biodiversity been studied or pest management undertaken to protect the native biota. This paper emphasises the importance of three key components of the eradication planning process for eradication projects in the tropical Pacific: an initial site assessment, community involvement and a well-prepared feasibility study. The purpose of these projects is the restoration of seabird populations on islands identified as Important Bird Areas. Local project manager was supported by an international partnership between Pacific Invasive Initiative, Birdlife International Pacific Secretariat and the New Zealand Department of Conservation. This support was directed at increasing the capability and capacity of local communities in eradicating invasive species from islands and maintaining pest free status for the benefit of native biota and the communities. Keywords: Ship rat, Rattus rattus, Pacific rat, Rattus exulans, brodifacoum, seabirds INTRODUCTION Introduced predators, especially rodents, have negative METHODS effects on seabirds (Burger and Gochfeld 1994; Thibault 1995; Rauzon 2007; Jones et al.. 2008) and eradicating Study site rodents from islands significantly benefits seabirds The north western coast of New Caledonia has a breeding populations (Lorvelec and Pascal 2005; Howald tropical climate with an average rainfall of 1159 mm (732 et al. 2007; Pascal et al. 2008). Successful eradications – 1613 mm) (ORSTOM 1981). The study area is a 20 km require robust planning (Cromarty et al. 2002) and social wide lagoon with 16 small islands ranging in size from acceptance by local communities (Boudjelas 2009). This 0.5 - 17 hectares situated between 1.5 and 10 km off the paper presents the strategy used from July 2007 until coast (Fig. 1). The islands are flat and sandy with a mixture March 2009 to eradicate introduced Pacific rats (Rattus of vegetation, ranging from short herbaceous ground exulans) and ship rats (R. rattus) on small islands identified cover through to coastal forest. Three of the islands have as Important Bird Areas (IBAs) in the North Lagoon of protruding rocky areas rising to an elevation of <50 m and New Caledonia (Spaggiari et al. 2007). one is a single sand bank. All of the islands are uninhabited The conservation goal of these projects was to restore but are regularly visited by local fishers and are popular seabird populations, especially those of the Polynesian storm places to visit for the local community. petrel (Nesofregatta fuliginosa) and fairy tern (Sternula nereis exsul; an endemic subspecies). The only recorded Feasibility phase breeding of Polynesian storm petrel in New Caledonia was The feasibility study (Baudat-Franceschi et al. on these islands in 1998 (Pandolfi and Bretagnolle pers. 2008) included three components: 1) an assessment of comm.). The area also hosts the last breeding population (100 pairs) of fairy tern (Baudat-Franceschi et al. 2009). Both of these species are preyed on by Rattus species (Hansen 2006; Thibault and Bretagnolle 1999; Pierce et al. 2007) so the provision of rodent free islands is likely to be of benefit. We first describe how biological surveys, early engagement with key stakeholders (notably local indigenous Kanak communities), and a feasibility study allowed us to decide if eradication was the appropriate pest management strategy. The feasibility study also helped us to develop eradication methods that fitted the local context. We then show how social acceptance of the project was achieved through ongoing consultation, information sharing with key stakeholders, and the participation of local community members in fieldwork. Finally, we describe the eradication method that was applied in the field. The benefits of consultation and involvement of local communities combined with a sound scientific and Fig. 1 New Caledonia showing the Important Bird Area with technical methodology are also discussed. islands from which rodents have now been eradicated. 26Pages 26-31 In: Veitch, C. R.; Clout, M. N. and Towns, D. R. (eds.). 2011. Island invasives: eradication and management. IUCN, Gland, Switzerland. Baudat-Franceschi et al.: Rodent eradication New Caledonia technical feasibility of eradicating rodents including non- whistling kite (Haliastur sphenurus), and brown goshawk target species risk assessment; 2) an overview of seabird (Accipiter fasciatus). Also at risk were shorebirds, raptors conservation needs to ensure eradication was the appropriate and gulls that breed on the islands: beach thick knee management choice; and 3) stakeholder issues, because (Esacus magnirostris), Pacific reef-egret (Egretta sacra operational feasibility also relies on social acceptance. albolineata), barn owl (Tyto alba delicatula) and silver gull Biological data were collected from rodent trapping and (Chroicocephalus novaehollandiae forsteri). Four species biodiversity surveys of plants, habitats, hermit crabs, ants, of vagrant shorebird present in low numbers on the islands reptiles, and birds. Reptiles and birds were the main non and which feed on invertebrates in the littoral zone were: target species. Assessing plants and habitats is necessary Pacific golden plover Pluvialis( fulva), ruddy turnstone to establish the site’s ecological characteristics. Ants as (Arenaria interpres), sanderling (Calidris alba), and a group include some highly invasive species. Hermit wandering tattler (Heteroscelus incanus). All passerines crabs are known to consume rodent bait, so assessing recorded on the islands were also at risk because they are their abundance is important for any eradication project insectivorous and frugivorous. Potential risk pathways (Wegmann et al. 2008). Consultation and involvement for all of the above species were through primary and/or of stakeholders began during this phase to build social secondary poisoning at the individual bird level (e.g., Eason acceptance. and Spurr 1995; Merton et al. 2002; McClelland 2002). However, all were common species and the risk to each at Rodent trapping the population level was very low. The exception was the Trapping was carried out on eight islands: Ouanne, Pouh, beach thick knee, a shorebird that feeds in the littoral zone. Yan dagouet, Tiam’bouène, Table, Double, Tangadiou, and Less than ten breeding pairs have been recorded in New Magone. The latter two were not considered priority IBA Caledonia, where the species is restricted to the Northern sites but could potentially act as stepping stone islands for lagoon (Baudat-Franceschi 2006). Because of their small rodent invasion between the mainland and Table Island. population size, this species was potentially at risk at the Because the distance between each island is <2 km, rats population level. could potentially swim from one island to the next (Russell Mitigation measures developed to ensure that risks were et al. 2005). Victor rat traps were deployed for three to minimised included: 1) timing the eradication to avoid the five nights consecutively; all traps were sheltered inside breeding period of most seabirds; 2) the use of bait stations corflute tunnels to avoid capturing seabirds. The traps were on beaches and other coastal habitats to reduce bait up take on grid formed of a transect line every 50 m, along which by invertebrates that might be eaten by beach thick knee was a trap every 25 m over the entire area of each island. and other shorebirds. From night 3 to night 5 (inclusive), Victor mouse traps were deployed between rat traps within the grid, on Table, Hermit crab assessment Tiam’bouène, Ouanne, Double, Yan dagouet, and Pouh High numbers of hermit crab have reduced bait Islands. Traps were baited with coconut and peanut butter as availability for target species (Bell 2002; Wegmann et late as possible in the afternoon to reduce the likelihood of al. 2008), so their numbers were assessed for our project. ants and cockroaches completely removing the bait before The first assessments were by night walks that followed nightfall. Trapping was carried out to confirm the presence beaches