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Burns, J H R

Craig, B K

Fukunaga, Atsuko

Kosaki, R K

Long-term ecological monitoring of reef fish populations often requires the simultaneous collection of data on benthic habitats in order to account for the effects of these variables on fish assemblage structure.

Globally important islands where eradicating invasive mammals will benefit highly threatened vertebrates

BRB

Holmes, Nick D [et al.]

Earths most highly threatened terrestrial insular vertebrates (111 of 1,184 species). Of these, 107 islands were in 34 countries and territories and could have eradication projects initiated by 2020. Concentrating efforts to eradicate invasive mammals on these 107 islands would benefit 151 populations of 80 highly threatened vertebrates and make a major contribution towards achieving global conservation targets adopted by the worlds nations.

South Africa works towards eradicating introduced house mice from sub-Antarctic Marion Island: the largest island yet attempted for mice

Beaumont, J.

Chauke, L.F.

Chown, S. L.

Cooper, J.

Devanunthan, N.

Dilley, B.J.

Dopolo, M.

Fikizolo, L.

Heine, J.

Henderson, S.

Jacobs, C.A.

Johnson, F.

Kelly, J.

Makhado, A.B.

Marais, C.

Maroga, J.

Mayekiso, M.

McClelland, G.

Mphepya, J.

Muir, D.N. Ngcaba, N. Ngcobo, J.P. Parkes, F. Paulsen, S. Schoombie, K. Springer, C. Stringer,H. Valentine, R.M. Wanless and P.G. Ryan

Preston, G.R.

House mice (Mus musculus) were introduced to South Africas sub-Antarctic Marion Island, the larger of the two Prince Edward Islands, by sealers in the early 19th century. Over the last two centuries they have greatly reduced the abundance of native invertebrates. Domestic cats (Felis catus) taken to the island in 1948 to control mice at the South African weather station soon turned feral, killing large numbers of breeding seabirds. An eradication programme finally removed cats from the island by 1991, in what is still the largest island area cleared of cats at 290 km2. Removal of the cats, coupled with the warmer and drier climate on the island over the last half century, has seen increasing densities of mice accumulating each summer. As resources run out in late summer, the mice seek alternative food sources. Marion is home to globally important seabird populations and since the early 2000s mice have resorted to attacking seabird chicks. Since 2015 c. 5% of summer-breeding albatross fledglings have been killed each year, as well as some winter-breeding petrel and albatross chicks. As a Special Nature Reserve, the Prince Edward Islands are afforded the highest degree of protection under South African environmental legislation. A recent feasibility plan suggests that mice can be eradicated using aerial baiting. The South African Department of Environmental Affairs is planning to mount an eradication attempt in the winter of 2021, following a partnership with the Royal Society for the Protection of Birds to eradicate mice on Gough Island in the winter of 2020. The eradication programme on Marion Island will be spearheaded by the South African Working for Water programme Africas biggest conservation programme focusing on the control of invasive species which is already driving eradication projects against nine other invasive species on Marion Island.

Improving the efficiency of aerial rodent eradications by means of the numerical estimation of rodenticide density

Aguirre-Muñoz, A.

Méndez-Sánchez, F.A.

Rojas-Mayoral, B.

Rojas-Mayoral, E.

Invasive rodents are present on approximately 80% of the worlds islands and constitute one of the most serious threats to island biodiversity and ecosystem functioning. The eradication of rodents is central to island conservation eff orts and the aerial broadcast of rodenticide bait is the preferred dispersal method. To improve the efficiency of rodent eradication campaigns, the generation of accurate and real-time bait density maps is required. Creating maps to estimate the spatial dispersion of bait on the ground has been carried out using traditional GIS methodologies, which are based on limiting assumptions and are time intensive. To improve accuracy and expedite the evaluation of aerial operations, we developed an algorithm for the numerical estimation of rodenticide density (NERD). The NERD algorithm performs calculations with increased accuracy, displaying results almost in real-time. NERD describes the relationship between bait density, the mass fl ow rate of rodenticide through the bait bucket, and helicopter speed and produces maps of bait density on the ground. NERD also facilitates the planning of helicopter fl ight paths and allows for the instant identification of areas with low or high bait density. During the recent and successful rodent eradication campaign on Banco Chinchorro in Mexico, carried out during 2015, NERD results were used to enable dynamic decision-making in the fi eld and to ensure the efficient use of resources.

Preventing extinctions: planning and undertaking invasive rodent eradication from Pinzon Island, Galapagos

Campbell, K.J.

Carrion, V.

Castaño, P.A.

Cunninghame, F.

Fisher, P.

Hagen, E.

Ponder, J.B.

Riekena, C.A.

Rueda, D.

Sevilla, C.

Shield, H.

Will, D.

Invasive black rats (Rattus rattus) were successfully eradicated during 2012 from Pinzon Island in the Galapagos archipelago using the rodenticide brodifacoum. Potential exposure to brodifacoum in Pinzon tortoises (Chelonoidis ephippium), Pinzon lava lizards (Microlophus duncanensis) and Galapagos hawks (Buteo galapagoensis) was mitigated by captive holding of subpopulations. This was successful for all species during and shortly after baiting, however mortality of Galapagos hawks occurred post-release, likely due to the persistence of residual brodifacoum in lava lizards. Since 2013, Pinzon tortoise hatchlings are surviving in-situ for the fi rst time in at least 120 years and the eradication of black rats is expected to have significant benefits for at least 15 other island-endemic species.

Eradicating black rats from the Chagos - working towards the whole archipelago

Carr, P.

Harper,G.A.

Pitman, H.

The Chagos Archipelago comprises some 58 islands covering 5,000 ha in the centre of the Indian Ocean. Black rats (Rattus rattus) were introduced about 230 years ago and have likely had a severe impact on the native terrestrial fauna, which is dominated by seabirds and land crabs. Most of the archipelagos terrestrial land mass is vegetated with old coconut plantations, with over 75% of the native forest cleared for coconut from 26 of the largest islands. Likely as a result of this colonisation and clearance, at least 30 islands have rats present (95.3% of the Chagos landmass) along with feral cats (Felis catus) on 62%, which suppresses the recovery of native fauna and fl ora. Efforts at rat eradication include the failed attempt on Eagle Island (252 ha) in the northern Chagos Archipelago in 2006 and the recent success of a ground-based eradication on Île Vache Marine in 2014, where two applications of brodifacoum poison were hand-spread at a rate of 18 kg/ha. Two islets on the nearby Salomon atoll were also cleared of black rats during the same operation with single bait applications. The 2014 operation was successful on what are regarded as difficult islands for rat eradication, being wet tropical islands with land crabs and coconut plantations present, and has engendered confidence to proceed with additional rat eradications on other northern Chagos islands.

Bridging the research-management gap: using knowledge exchange and stakeholder engagement to aid decision-making in invasive rat management

Ewen, J.G.

Ferrière, C.

Jones, C.G.

Maggs, G.

Murrell, D.J.

Nicoll, M.A.C.

Norris, K.

Tatayah, V.

Zuël, N.

The world is facing a biodiversity crisis. Nowhere is that more apparent than on oceanic islands where invasive species are a major threat for island biodiversity. Rats are one of the most detrimental of these and have been the target of numerous eradication programmes; a well-established conservation tool for island systems. For at-risk native species inhabiting large, populated islands, where rat eradication is not an option, control of rat populations has been conducted but this requires continuous management and therefore its long-term viability (and that of the at-risk native species which the project aims to protect) can be uncertain. Large-scale rat management areas or mainland islands have been successfully developed in New Zealand. However, large-scale management is a long-term investment with huge financial implications and committing to such an investment can be met with reluctance. This reluctance, and its subsequent hindrance to decision-making, can be caused by uncertainty relating to species conservation outcomes, and the multiple objectives of stakeholders. We address the issue of uncertainty and the importance of communication between all stakeholder parties in relation to the Mauritius olive white-eye (Zosterops chloronothos), a critically endangered passerine endemic to Mauritius and highly threatened by invasive rats. Specifically, we illustrate how the combination of scientific research and communication, knowledge exchange, and stakeholder workshops, can address some of the barriers of decision-making, helping to bridge the research-management gap, and enable the timely expansion of existing rat management for the benefit of this highly threatened bird.

Timing aerial baiting for rodent eradications on cool temperate islands: mice on Marion Island

Parkes, J.P.

Aerial baiting from helicopters with a bait-sowing bucket and GPS to ensure coverage with anticoagulant toxins in cereal-based baits can reliably eradicate rodents on islands. Current best practice for temperate islands is to bait in winter when the rodents are not breeding, rodent numbers are lowest so competition for toxic baits is lowest, natural food is likely to be scarce, and many non-target species are absent from the island. However, short winter day lengths at high latitudes restrict the time helicopters can fly and poor weather in winter may increase risks of failure. This paper notes precedents from cool temperate islands where baiting was not conducted in winter and then uses the extensive data on mice on Marion Island to explore whether current recommendations for winter baiting based on breeding and natural food availability are important risk factors in determining time of year to bait. Marion Island mice do not breed between early May and late September, mouse densities reach a maximum in May and minimum in November, but the biomass of main natural food (invertebrates) does not fluctuate greatly over the year. This means the per capita food availability is least in autumn and increases through winter to most in spring and summer. The weight of the stomach contents of mice is also highest in winter. Based on this per capita food parameter, mice are likely to be most hungry between about March and May suggesting baiting would be more effective in this period (perhaps towards the end of it when breeding stops) than in the more traditional winter season.

A potential new tool for the toolbox: assessing gene drives for eradicating invasive rodent populations

Brown, P.R.

Campbell, K.J.

Delborne, J.

Godwin, J.

Gould, F.

Howald, G.R.

Kanavy, D.M.

Kuiken, T.

Packard, H.

Piaggio, A.

Saah, J.R.

Serr, M.

Shiels, A.

Thomas, P.

Threadgill, D.

Tompkins, D.M.

Invasive rodents have significant negative impacts on island biodiversity. All but the smallest of rodent eradications currently rely on island-wide rodenticide applications. Although significant advances have been made in mitigating unintended impacts, rodent eradication on inhabited islands remains extremely challenging. Current tools restrict eradication efforts to fewer than 15% of islands with critically endangered or endangered species threatened by invasive rodents. The Genetic Biocontrol of Invasive Rodents partnership is an interdisciplinary collaboration to develop and evaluate gene drive technology for eradicating invasive rodent populations on islands. Technological approaches currently being investigated include the production of multiple strains of Mus musculus with a modified form of the native t-complex, or a CRISPR gene drive, carrying genes or mechanisms that determine sex. These systems have the potential to skew the sex ratio of off spring to approach 100% single-sex, which could result in population collapse. One goal proposed is to test the ability of constructs to spread and increase in frequency in M. musculus populations in biosecure, captive settings and undertake modelling to inform development and potential deployment of these systems. Structured ecologically-based risk assessments are proposed, along with social and cultural engagement to assess the acceptability of releasing a gene drive system. Work will be guided by an external ethics advisory board. Partners are from three countries with significant regulatory capacity (USA, Australia, New Zealand). Thus, we will seek data sharing agreements so that results from experiments may be used within all three countries and treat regulatory requirements as a minimum. Species-specific, scalable, and socially acceptable new eradication tools could produce substantial biodiversity benefits not possible with current technologies. Gene drive innovation may provide such a tool for invasive species management and be potentially transformative and worthy of exploring in an inclusive, responsible, and ethical manner.

Black rat eradication on Italian islands: planning forward by looking backward

Baccetti, N.

Capizzi, D.

Gotti, C.

Pelliccioni, E. Raganella

Petrassi, F.

Sozio, G.

Sposimo, P.