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Marine Debris Pollution in the Pacific : Literature review
Climate Change Resilience, Island and Ocean Ecosystems, Waste Management and Pollution Control, BRB
Available Online

Secretariat of the Pacific Regional Environment Programme (SPREP)

2014
Rapidly expanding human populations and associated economic growth and overconsumption is resulting in serious degradation of the natural environment human survival depends on (Vitousek et al., 1997; Sanderson et al., 2002; Orr, 2004; Alroy, 2010; Branch et al., 2013). Almost half of the global human population currently lives within 150km of the coast (UN Atlas of the Oceans, 2014). This results in severe pressures being placed on marine and coastal environments. Anthropogenic impacts on oceans include physical alterations of the coasts and seafloor, as well as chemical and biological contamination through sewage, industrial wastes and agricultural discharges, dredging, desalination, shipping, and fossil fuel and ore extraction. These pressures, together with overfishing, by-catch, destructive fishing methods (e.g. blast fishing), introduction of invasive species, boat strikes, acoustic pollution, climate-related changes (i.e. ocean acidification, sea level rise, freshwater inundations, cyclones) can cause structural changes in marine communities and the loss of genetic variability and other side-effects of human interference with exceptionally complex ocean ecosystems (Gray et al., 1979; Goldberg, 1995; Vitousek et al. 1997; Islam and Tanaka, 2004; Pauly et al., 2005; Panigada et al., 2006; Crain et al., 2008; Halpern et al., 2008; Ramirez-Llodra et al., 2011)
Special Issue Article: Tropical rat eradication. Seabird recovery and vegetation dynamics after Norway rat eradication at Tromelin Island, western Indian Ocean. Biological Conservation. Volume 185, May 2015
Island and Ocean Ecosystems, BRB
Available Online

Bastien. M

,

Danckwerts. D.K

,

M. Le Corre. M

,

Micol. T

,

Morey Rubio.C

,

Orlowski. S

,

Pinaud. D

,

Ringler. D

2015
Seabirds are notoriously sensitive to introduced mammalian predators and eradication programs have benefitted seabird populations and their habitats on numerous islands throughout the world. However, less evidence is available from the tropics as to the benefits of rat eradication. Here, we report the seabird recovery and vegetation dynamics on a small coralline island of the tropical western Indian Ocean, eight years after Norway rat (Rattus norvegicus) eradication. Two species of seabirds were breeding before rat eradication (red-footed and masked boobies, Sula sula and Sula, dactylatra) and, in both species, the number of breeding pairs had an apparent increase of 22?23% per year after rat eradication. Such a high annual growth rate cannot be achieved by auto-recruitment only and our data suggest that immigration from other source populations never occurred in at least one of these species. We suggest that it is rather due to a rapid increase in breeding success, which rapidly increased the observed number of breeders since birds remained in the available-for-counting-as-breeders group for much longer. Two other species, the white tern (Gygis alba) and the brown booby (Sula leucogaster) were recorded breeding in 2014. The former species has not bred on the island since 1856 and the latter has never bred on the island. Plant cover (monospecific formation of the ruderal herb Boerhavia diffusa) dramatically increased from less than 30% of surface coverage to more than 70%. Although the initial restoration project was to eradicate all introduced mammals of the island simultaneously, house mouse (Mus musculus) eradication failed. Mouse density was high 8 years after rat eradication (32 mice/ha in dry season and 52 mice/ha in rainy season) but not higher than at a comparable tropical island of the region (Juan de Nova) where mice coexist with introduced black rats (Rattus rattus) and feral cats (Felis catus). These results are discussed in terms of the direct positive effects of rat eradication on seabirds and plants and the indirect positive effects of post-eradication seabird increase on soil manuring and vegetation recovery. Overall, our results show that on tropical islands, seabird and habitat recovery can be very rapid after rat eradication and should be implemented as a restoration tool wherever possible.
Special Issue Article: Tropical rat eradication. The next generation of rodent eradications: Innovative technologies and tools to improve species specificity and increase their feasibility on islands. Biological Conservation. Volume 185, May 2015
Island and Ocean Ecosystems, BRB
Available Online

Baxter. G.S.

,

Beek. J

,

Campbell K.J

,

Eason C.T

,

Glen A.S

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Godwin. J

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Gould. F

,

Holmes. N.D

,

Howald. G.R

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Madden F.M

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Ponder J.B

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Threadgill. D.W

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Wegmann. A.S

2015
Rodents remain one of the most widespread and damaging invasive alien species on islands globally. The current toolbox for insular rodent eradications is reliant on the application of sufficient anticoagulant toxicant into every potential rodent territory across an island. Despite significant advances in the use of these toxicants over recent decades, numerous situations remain where eradication is challenging or not yet feasible. These include islands with significant human populations, unreceptive stakeholder communities, co-occurrence of livestock and domestic animals, or vulnerability of native species. Developments in diverse branches of science, particularly the medical, pharmaceutical, invertebrate pest control, social science, technology and defense fields offer potential insights into the next generation of tools to eradicate rodents from islands. Horizon scanning is a structured process whereby current problems are assessed against potential future solutions. We undertook such an exercise to identify the most promising technologies, techniques and approaches that might be applied to rodent eradications from islands. We highlight a Rattus-specific toxicant, RNA interference as species-specific toxicants, rodenticide research, crab deterrent in baits, prophylactic treatment for protection of non-target species, transgenic rodents, virus vectored immunocontraception, drones, self-resetting traps and toxicant applicators, detection probability models and improved stakeholder community engagement methods. We present a brief description of each method, and discuss its application to rodent eradication on islands, knowledge gaps, challenges, whether it is incremental or transformative in nature and provide a potential timeline for availability. We outline how a combination of new tools may render previously intractable rodent eradication problems feasible.
Special Issue Article: Tropical rat eradication. Improving the odds: Assessing bait availability before rodent eradications to aid in selecting bait application rates. Biological Conservation. Volume 185, May 2015
Island and Ocean Ecosystems, BRB
Available Online

Berentsen. A.R

,

Brooke. M.L

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Cuthbert. R.J

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Griffiths. R.

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Holmes. N.D

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Howald. G.R

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Pitt. W.C

,

Pott. M

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Ramos-Rend¢n. G

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Russell. J.C

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Samaniego-Herrera. A

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Wegmann. A.S

2015
Rodent eradications undertaken on tropical islands are more likely to fail than eradications undertaken at higher latitudes. We report on 12 independent rodent eradication projects undertaken on tropical islands that utilized the results of an in situ bait availability study prior to eradication to inform, a priori, the bait application rate selected for the eradication. These projects also monitored bait availability during the eradication. The results from our analysis verified the utility of bait availability studies to future rodent eradication campaigns and confirmed the influence of two environmental factors that can affect bait availability over time: precipitation prior to the study and the abundance of land crabs at the study site. Our findings should encourage eradication teams to conduct in-depth assessments of the targeted island prior to project implementation. However, we acknowledge the limitations of such studies (two of the projects we reviewed failed and one removed only one of two rodent species present) and provide guidance on how to interpret the results from a bait availability study in planning an eradication. Study design was inconsistent among the twelve cases we reviewed which limited our analysis. We recommend a more standardized approach for measuring bait availability prior to eradication to provide more robust predictions of the rate at which bait availability will decrease during the eradication and to facilitate future comparisons among projects and islands.
Special Issue Article: Tropical rat eradicationBest practice guidelines for rat eradication on tropical islands. Biological Conservation. Volume 185, May 2015
Island and Ocean Ecosystems, BRB
Available Online

Boudjelas. S

,

Broome. K

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Cranwell. S

,

Griffiths. R

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Keitt. B

,

Millett. J

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Pitt. W

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Samaniego-Herrera. A.

2015
Invasive vertebrates are a leading cause of the extinction on islands and rats (Rattus spp.) are one of the most damaging to island ecosystems. Methods to eradicate rates from islands are well established and there have been over 580 successful eradications to date. Increasingly, rat eradications are being implemented on tropical islands, a reflection of the need to protect the threatened biodiversity in the tropics. Yet rat eradications on tropical islands fail more frequently than those in temperate climates. In an effort to identify the main reasons for the lower success rate on tropical islands and possible solutions, a workshop was convened with the 34 experts in rat eradication, tropical rodent and island ecology and toxicology. The workshop focused on projects using aerial broadcast of brodifacoum, a 2nd generation anticoagulant, because this approach had provided the highest success rate for eradicating rodents from islands. The workshop participants reviewed previously identified challenges to successful rat eradications on tropical islands including increased insect and crab densities resulting in competition for bait, year round or unpredictable timing of breeding rats and increased or unpredictable availability of alternative, natural foods. They also identified a number of new, likely reasons for the lower success rate on tropical islands and provided recommendations for how to address these risks in the planning and implementation of rat eradications. While the success rate of aerial broadcast rat eradications in tropical environments is quite high at 89%, it is hoped that by following the recommended best practices provided in this paper, future success rates will be closer to the 96.5% demonstrated for aerial broadcast rat eradication on temperate islands.
Special Issue Article: Tropical rat eradication. The response of black rats (Rattus rattus) to evergreen and seasonally arid habitats: Informing eradication planning on a tropical island. Biological Conservation. Volume 185, May 2015
Island and Ocean Ecosystems, BRB
Available Online

Grant A. Harper

,

James C. Russell

,

Martijn van Dinther

,

Nancy Bunbury

2015
Rat eradications on tropical islands have been less successful than operations in temperate climates. This is likely due to poor understanding of the factors unique to tropical regions that rat populations respond to, such as high numbers of land crabs, aseasonal climates and habitats not found at higher latitudes. On Aldabra Atoll, southern Seychelles, black rats were monitored for one year in three habitats over three climatic seasons to investigate changes in density and breeding to inform planning for a possible rat eradication. Rats bred all year in mangrove forest and in two of three seasons, including the dry season, in Pemphis forest, probably resulting from the saline tolerance of these habitats: lush vegetation and seeds were available there during the dry season. In contrast, rats from the adjacent mixed-scrub habitat only bred in the wet season due to desiccation of vegetation and lack of fresh water during other times of the year. Bait consumption trials showed that all rats ingested dyed bait when applied at 15 kg/ha, despite high rat densities and substantial bait interference by non-target species, but not at an application rate of 10 kg/ha. A novel ‘bola’ technique was tested for distributing bait into mangrove forest, where aerially applied rat bait would normally be lost due to tidal inundation. The method is likely to improve rat exposure to bait in mangrove forest and other habitats on tropical islands, and warrants further development.
Special Issue Article: Tropical rat eradication. Invasive rat interactions and over-invasion on a coral atoll. Biological Conservation. Volume 185, May 2015
Island and Ocean Ecosystems, BRB
Available Online

Anderson S.H

,

Caut. S

,

Lee. M.

,

Russell. J.C

2015
Invasive rats are found on most island groups of the world, and usually more than one species has invaded. On tropical islands populations of different invasive rat species can co-exist on very small islands, but the population dynamics of such co-existing rat species, their impact on each other, and the mechanisms of coexistence are not well known. This lack of knowledge is a barrier to improving the success rate of tropical island rat eradications. Through an exhaustive trapping eradication campaign on a small tropical island, we study the population structure of historically established Rattus exulans where R. rattus have colonised within the last fifty years and over-invaded. We contrast this R. exulans population with a nearby island population where R. exulans exist alone. Recently invaded R. rattus numerically and morphologically dominate R. exulans; however stable isotope analyses show that the trophic position of R. exulans remains consistent regardless of the presence of R. rattus, once differences in trophic foundations of islands are accounted for. Although the trophic position of both rat species is indistinguishable, R. rattus is able to dominate R. exulans through interference competition. Our eradication attempt was interrupted by a tropical cyclone and ultimately unsuccessful, but there is some evidence that R. rattus reduced control device availability to R. exulans, which has important implications for multi-species control operations.