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Santa Cruz, California, United States

Johnson W.C.,South Dakota State University | Poiani K.A.,Island Conservation
Wetlands | Year: 2016

This paper reviews the findings of a 25-year project (1990–2015) that has examined the potential effects of climate change on the vegetation structure, hydrologic function, and biodiversity of wetlands in the Prairie Pothole Region (PPR) of North America. The numerical modeling component of the project developed in phases, beginning with the building of a single basin model (WETSIM), followed by a multiple-basin model (WETLANDSCAPE-WLS), and ending with applications of a comprehensive WLS model to specific wetland issues: ecological thresholds and early detection of effects. Coincident with model development was the establishment of a long-term wetland monitoring field site (Orchid Meadows) that includes 18 years of continuous surface and groundwater data on a wetland complex. Also during the project, an intensive study of the historic climate of the PPR was conducted. Model simulations support the following conclusions: prairie wetlands are highly sensitive to climate change; a warmer climate without more precipitation will shrink the effective wetland area of the PPR and reduce waterfowl habitat; strong climatic gradients across the PPR, especially the strong east to west decline in precipitation, complicate the response of PPR wetlands to climate change and approaches to mitigation. © 2016 Society of Wetland Scientists Source

Russell J.C.,University of Auckland | Holmes N.D.,Island Conservation
Biological Conservation | Year: 2015

Invasive rats have found their way to most islands throughout the world, where they have had and continue to have severe negative impacts on insular biota. Techniques developed in temperate regions to eradicate invasive rats from islands have proven to be one of the most powerful conservation tools available for island restoration. Tropical islands contain unique biodiversity also threatened by invasive rats, but eradication attempts in tropical environments have a higher failure rate. In particular rat eradications have failed more often on islands with high mean annual temperatures, and medium levels of annual precipitation which remain constant throughout the year. How these tropical ecological conditions interact to influence the likelihood of eradication success remains poorly understood. To synthesise current knowledge on the eradication of rats on tropical islands this special issue presents nine papers following a workshop reviewing tropical island rat eradications convened in Auckland, New Zealand in August 2013. These papers present state-of-the-art reviews of the field, best practice recommendations for operational implementation, novel research on rat ecology which will inform future eradication planning, and evidence of species recovery following rat eradication. In the future, biologists will need to contribute to our understanding of tropical island dynamics, particularly with respect to rat eradication, while eradication practitioners should seek to understand more deeply the role of tropical environments in eradication success, so that the implementation and success rate of tropical island rat eradications can increase, and the potential for tropical island restoration fully realised. © 2015 Elsevier Ltd. Source

Aslan C.,Arizona Sonora Desert Museum | Holmes N.,Island Conservation | Tershy B.,University of California at Santa Cruz | Spatz D.,University of California at Santa Cruz | Croll D.A.,University of California at Santa Cruz
Conservation Biology | Year: 2015

Protected area delineation and conservation action are urgently needed on marine islands, but the potential biodiversity benefits of these activities can be difficult to assess due to lack of species diversity information for lesser known taxa. We used linear mixed effects modeling and simple spatial analyses to investigate whether conservation activities based on the diversity of well-known insular taxa (birds and mammals) are likely to also capture the diversity of lesser known taxa (reptiles, amphibians, vascular land plants, ants, land snails, butterflies, and tenebrionid beetles). We assembled total, threatened, and endemic diversity data for both well-known and lesser known taxa and combined these with physical island biogeography characteristics for 1190 islands from 109 archipelagos. Among physical island biogeography factors, island area was the best indicator of diversity of both well-known and little-known taxa. Among taxonomic factors, total mammal species richness was the best indicator of total diversity of lesser known taxa, and the combination of threatened mammal and threatened bird diversity was the best indicator of lesser known endemic richness. The results of other intertaxon diversity comparisons were highly variable, however. Based on our results, we suggest that protecting islands above a certain minimum threshold area may be the most efficient use of conservation resources. For example, using our island database, if the threshold were set at 10 km2 and the smallest 10% of islands greater than this threshold were protected, 119 islands would be protected. The islands would range in size from 10 to 29 km2 and would include 268 lesser known species endemic to a single island, along with 11 bird and mammal species endemic to a single island. Our results suggest that for islands of equivalent size, prioritization based on total or threatened bird and mammal diversity may also capture opportunities to protect lesser known species endemic to islands. © 2014 Society for Conservation Biology. Source

Spatz D.R.,University of California at Santa Cruz | Newton K.M.,University of California at Santa Cruz | Heinz R.,University of California at Santa Cruz | Tershy B.,University of California at Santa Cruz | And 3 more authors.
Conservation Biology | Year: 2014

Seabirds are the most threatened group of marine animals; 29% of species are at some risk of extinction. Significant threats to seabirds occur on islands where they breed, but in many cases, effective island conservation can mitigate these threats. To guide island-based seabird conservation actions, we identified all islands with extant or extirpated populations of the 98 globally threatened seabird species, as recognized on the International Union for Conservation of Nature Red List, and quantified the presence of threatening invasive species, protected areas, and human populations. We matched these results with island attributes to highlight feasible island conservation opportunities. We identified 1362 threatened breeding seabird populations on 968 islands. On 803 (83%) of these islands, we identified threatening invasive species (20%), incomplete protected area coverage (23%), or both (40%). Most islands with threatened seabirds are amenable to island-wide conservation action because they are small (57% were <1 km2), uninhabited (74%), and occur in high- or middle-income countries (96%). Collectively these attributes make islands with threatened seabirds a rare opportunity for effective conservation at scale. © 2014 Society for Conservation Biology. Source

Griffiths R.,Island Conservation | Miller A.,University of Auckland
Pacific Conservation Biology | Year: 2011

Consumption of rodent bait by land crabs, leaving some rodents unexposed, has been described as one potential reason why several rodent eradications undertaken on mesic-tropical islands have failed. Strategies to overcome the issue have been proposed but all increase the risk, cost or logistics of running an eradication operation. To quantify the impact of land crabs and assess the feasibility of achieving rodent eradication using a standard bait application rate used in temperate climates, we measured crab density, rates of bait take and exposure of rats to bait on Vahanga Atoll in French Polynesia. The two methods used to measure crab density were closely correlated and agreed with anecdotal observations, suggesting they were a reliable index of crab numbers. Rates of bait take were closely correlated with crab density providing a potential means of predicting bait take in a crab dominated ecosystem such as Vahanga, an advantage when planning a rodent eradication attempt. At some sites on Vahanga, crabs were in sufficient numbers (up to 5 900/ha) to rapidly reduce bait availability but even at these sites rats were able to access bait. The result suggests that achieving rat eradication on some mesic-tropical islands may be possible using a typical temperate climate bait application rate. However, our results should be applied with caution because we did not determine the amount of bait consumed by rats. Source

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