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.
News Article | March 21, 2016
The study, titled "Invasive mammal eradication on islands results in substantial conservation gains," examined how native species responded to projects that eradicated invasive mammals from islands. The researchers found 596 populations of 236 native species on 181 islands benefitted from these eradications. The study is scheduled for publication the week of March 21, 2016 in the online Early Edition of the journal, Proceedings of the National Academy of Sciences. "We've known that invasive mammal eradications are a powerful conservation tool, but this is the first time the benefits have been quantified at the global scale," said lead author Holly Jones, assistant professor in biological sciences and the Institute for the Study of the Environment, Sustainability, and Energy at Northern Illinois University. "Twenty one billion dollars (US) are spent globally each year on nature conservation. A small fraction of this goes to eradication of invasive species, yet this relatively simple, cost-effective conservation intervention is benefitting hundreds of native animals and endangered species. This is fantastic news in the race to prevent extinctions." "These island restoration projects are a proverbial silver bullet for biodiversity conservation," said co-author Nick Holmes, director of science for Island Conservation, a non-profit organization with a mission to prevent extinctions by removing invasive species from islands. "For any conservation intervention, it is rare to find a body of global evidence measuring the outcomes for native species. These results are a testament to the value of these types of projects and the practitioners advancing them around our world." The research team conducted a large-scale literature and database review along with expert interviews to estimate the benefits to native species of removing invasive mammals found on islands. The researchers documented positive responses, including population increases, recolonization and successful reintroductions. Four species that qualified for down-listing to a lower category of extinction risk on the IUCN Red List, in part due to invasive mammal eradication, were the Island fox (California), Seychelles magpie robin (Seychelles), Cook's petrel (New Zealand) and Black-vented shearwater (Mexico). Once introduced to islands, invasive mammals—primarily rodents, feral goats and feral cats—represent key threats to native species through predation, competition and habitat loss. "Humans have introduced non-native, invasive mammals (accidentally or intentionally) to 90 percent of the world's island archipelagos," said co-author Don Croll, a biology professor at the University of California Santa Cruz. "These mammals have devastating consequences for ecosystems because island species evolved in isolation without these mammalian predators. They have little to no defense against invasive mammals." Islands with invasive species pose a unique biodiversity conservation challenge and opportunity. Islands occupy less than 6 percent of Earth's land area, yet are home to 15 percent of terrestrial species. Islands represent 61 percent of recorded extinctions with invasive species implicated in the majority of those. Thirty-seven percent of all Critically Endangered Species on the IUCN Red List are found on islands. "Invasive alien species are causing an extinction crisis on the world's islands, but our research shows that this is one problem for which we have the tools to tackle, and the results can be spectacularly successful," said co-author Stuart Butchart, head of science at BirdLife International, the world's largest partnership of nature conservation organizations. The researchers' noted examples of responses included: The New Zealand storm-petrel, thought extinct for more than 150 years, was recently found breeding on Little Barrier Island following cat and rat eradication. The Scripps' murrelet is no longer a candidate for listing on the U.S. Endangered Species Act following rat eradication on Anacapa Island. The California Channel Islands' endemic Island fox has been proposed to be removed from the Endangered Species Act following intensive conservation efforts, including a feral pig eradication on Santa Cruz Island. Documented beneficiaries of invasive mammal eradications are likely underreported because of a lack of monitoring, the researchers added. Biologists have long been aware of the damage that can be done at the hands of invasive species. In February 1894, in New Zealand, one of the Stephens Island lighthouse keepers' pregnant house cats escaped, went feral, and the population rocketed. By March 1895, cats were largely responsible for driving the Stephens Island wren to extinction. On the Pacific Ocean's Kiritimati Island, cats and rats wiped out the Christmas sandpiper in the late 1800s. Cats on Guadalupe Island, Mexico, drove the Guadalupe storm-petrel to extinction in the early 1900s. There are hundreds more stories like this. In recent decades, eradication programs have gained traction even on more populated islands. More than 1,100 attempts at eradication of invasive mammal populations have occurred. "Many eradication techniques were first developed in New Zealand, so much so that it's been commonplace to 'call the Kiwis' if you want to eradicate mammals," Jones said. "Now, more and more conservation organizations worldwide are embracing this conservation intervention." Jones hopes the study's results will help conservation practitioners see where they can make further strides to curb extinctions and protect native species. "While we can't bring back the species that have gone extinct, our analysis shows that removing invasive mammals can help us undo some of the damage we've caused," she said. Explore further: Introducing species to change ecosystems is a balancing act More information: Invasive mammal eradication on islands results in substantial conservation gains, www.pnas.org/cgi/doi/10.1073/pnas.1521179113
News Article | September 6, 2016
The Bill and Melinda Gates Foundation plans to double the sum it is spending to create a mosquito-killing technology that relies on CRISPR gene editing. The technique, called a gene drive, is a way to spread traits through wild populations of animals, but its ability to alter nature is drawing opposition from some environmental groups. The Gates-funded project, called Target Malaria, is based at Imperial College, London, and has been seeking to add instructions to the DNA of malaria mosquitoes that would cause them to become sterile. If released in the wild, a gene drive could push these species to extinction. Spokesman Bryan Callahan says the Gates Foundation will give Target Malaria an additional $35 million, bringing Gates’s total investment to $75 million. That is the largest sum ever spent on gene-drive technology. Scientists at Imperial and elsewhere first succeeded in installing gene drives in mosquitoes last year—in lab research—setting off a global debate over whether the technology is safe enough to use. The new money will help Target Malaria “explore the potential development of other constructs, as well as to start mapping out next steps for biosafety, bioethics, community engagement, and regulatory guidance,” says Callahan. “It’s basically a lot of groundwork.” The Gates Foundation views the technology as a “long shot” that won’t necessarily work but, if it does, could effectively end malaria. The foundation previously said it plans to have a gene-drive approved for field use by 2029 somewhere in Africa. But Gates, the founder of Microsoft, offered more enthusiastic prognostications in comments made this summer, saying the technology might be ready in just two years. A gene drive works by spreading genetic instructions as animals mate. For instance, if a drive causes only male animals to be born, a population would quickly crash as it runs out of females. It may also be possible to change mosquitoes so they are unable to transmit malaria, which is a significant cause of death in children in sub-Saharan Africa. In a report earlier this year, the National Academies of Sciences, Engineering, and Medicine in Washington, D.C., said gene drives were not yet ready for environmental release, but laid out steps that should be taken to test them safely, recommendations the Gates Foundation says it will follow. Genetic techniques for “bio-control” have also caught the eye of conservationists as a way to kill off invasive species, including mosquitoes, rats, toads, or fish that take over ecosystems and can drive local species to extinction. Over the weekend, during the world congress of the International Union of Conservation of Nature in Hawaii, the nonprofit Island Conservation announced it had started a project to genetically engineer mice so they only produce male offspring. The group believes gene drives will be a way to wipe invasive rodents off islands and archipelagos, where they prey on birds and lizards. Other researchers hope to eradicate mosquitoes from Hawaii in order to save the island chain’s remaining native birds, which are succumbing to the avian form of malaria. Other conservation groups, however, circulated a petition at the Hawaii meeting calling for a moratorium on the idea. They worry that promoting drives as conservation tools could pave the way for commercial use of gene drives, say to manage agricultural pests. “Genetic extinction technologies are a false and dangerous solution to the problem of biodiversity loss,” Erich Pica, president of the Friends of the Earth, said in a statement signed by anti-GMO campaigners that called the technology reckless. Heath Packard, a spokesman for Island Conservation, said his group is willing to consider the technology because 90 percent of the world’s island chains are infested with rodents. It has previously eradicated rats from some islands, including in the Galapagos, using poisoned bait. But efforts to poison rats are expensive, hard to pull off on larger islands, and can create risks for other animals. Packard says the mouse project is being carried out with Texas A&M, North Carolina State University, and the U.S. Department of Agriculture. While mice aren’t as big a problem as rats, they have infested the Midway atoll in the Pacific, and videos posted online of them eating albatross chicks alive have galvanized bird lovers. He says the nonprofit hopes to have a proposal in front of regulators for a field trial within four years. The debate over drives could rival that over GMOs in its intensity and, ultimately, its global consequences. That is because, like GMO plants, the gene drives would affect our shared environment. But conservationists and public health campaigners see a one-of-a-kind chance to solve big problems and aren’t likely to stop their efforts to perfect the technology in the lab. “We need some transformative end-game technologies, and this is one of them,” says Callahan.
Pitt W.C.,U.S. Department of Agriculture |
Berentsen A.R.,U.S. Department of Agriculture |
Shiels A.B.,U.S. Department of Agriculture |
Volker S.F.,U.S. Department of Agriculture |
And 3 more authors.
Biological Conservation | Year: 2015
The use of rodenticides to control or eradicate invasive rats (Rattus spp.) for conservation purposes has rapidly grown in the past decades, especially on islands. The non-target consequences and the fate of toxicant residue from such rodent eradication operations have not been well explored. In a cooperative effort, we monitored the application of a rodenticide, 'Brodifacoum 25W: Conservation', during an attempt to eradicate Rattus rattus from Palmyra Atoll. In 2011, Brodifacoum 25W: Conservation was aerially broadcasted twice over the entire atoll (2.5km2) at rates of 80kg/ha and 75kg/ha and a supplemental hand broadcast application (71.6kg/ha) occurred three weeks after the second aerial application over a 10ha area. We documented brodifacoum residues in soil, water, and biota, and documented mortality of non-target organisms. Some bait (14-19% of the target application rate) entered the marine environment to distances 7m from the shore. After the application commenced, carcasses of 84 animals representing 15 species of birds, fish, reptiles and invertebrates were collected opportunistically as potential non-target mortalities. In addition, fish, reptiles, and invertebrates were systematically collected for residue analysis. Brodifacoum residues were detected in most (84.3%) of the animal samples analyzed. Although detection of residues in samples was anticipated, the extent and concentrations in many parts of the food web were greater than expected. Risk assessments should carefully consider application rates and entire food webs prior to operations using rodenticides. © 2015 .
Holmes N.D.,Island Conservation |
Griffiths R.,Island Conservation |
Pott M.,Island Conservation |
Alifano A.,Island Conservation |
And 3 more authors.
Biological Conservation | Year: 2015
Invasive rodents have an overwhelmingly detrimental impact to native flora and fauna on islands. Rodent eradications from islands have led to valuable biodiversity conservation outcomes. Tropical islands present an additional suite of challenges for rat eradications due to unique characteristics associated with these environments. To date tropical island rat eradications have failed at a higher rate than those undertaken outside the tropics. Critical knowledge gaps exist in our understanding of what drives this outcome. We collated an in-depth dataset of 216 rodenticide based rat eradication operations (33% of all known rodent eradications) in order to determine correlates of eradication failure, including both project implementation factors and target island ecology, geography and climate. We assessed both failed and successful projects, and projects inside and outside the tropics, using random forests, a statistical approach which compensates for high dimensionality within, and correlation among, predictor variables. When assessing all projects, increasing mean annual temperature, particularly above 24. °C, underscored the higher failure rate and greater difficulty of rodent eradications on islands in lower latitudes. We also found clear trends in eradication failure for factors unique to the tropics, including the presence of land crabs - burrowing and hermit crabs, and coconut palms (. Cocos nucifera). The presence of agriculture was also associated with failure. Aerial operations had a higher success rate than ground-based methods but success with this technique was less likely in the presence of hermit crabs and other non-target bait consumers. Factors associated with failure in ground-based eradication methods suggested limitations to project scaling such as island area and number of staff. Bait station operations were less likely to succeed when using stopping rules based on measures of rodent abundance. Factors influencing rat eradication failure in tropical environments continue to require a deeper understanding of tropical island dynamics to achieve a higher rate of eradication success. © 2015 Elsevier Ltd.
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.
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
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.
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.
News Article | August 18, 2016
Eight of every 10 species extinctions has occurred on islands, and invasive mammals are the leading reason for those losses. Currently, 40 percent of species at risk of global extinction are island inhabitants. In the most thorough study of its kind, scientists have now analyzed global patterns of island vertebrate extinctions and developed predictive models to help identify places where conservation interventions will provide the greatest benefits to threatened island biodiversity. Control and eradication of invasive species are effective conservation tools, but conservation scientists have lacked tools for identifying where these efforts will have the greatest impact. The new study, published August 18 in Nature Communications and led by UC Santa Cruz researcher Erin McCreless, closes that gap. Humans have introduced non-native rodents, destructive herbivores such as goats, and predators like feral cats and foxes to islands around the world. These novel disturbances decimate native island wildlife and change entire island ecosystems. At the same time, islands are hotspots of biodiversity and often support rare and unique species occurring nowhere else in the world. Controlling invasive mammal populations, or removing them entirely from islands, is a highly effective tool for conserving island species and ecosystems, and such actions have contributed greatly to the recovery of many threatened island species. Conservation dollars are limited, however, and it is important that invasive mammal management efforts be focused on the islands where they will go the furthest toward conserving native island biodiversity. "Until now, conservation scientists have chosen islands for invasive mammal management largely based on the need to protect a particular native species, or on broader assumptions about how native species are likely being affected," McCreless said. For example, invasive rats are often eradicated on islands where they have been seen eating native birds and their chicks. "However, as these conservation efforts increase globally, conservationists need to take a more strategic approach and choose islands based on a more complete, larger-scale understanding of how different invasive mammals affect native species on different types of islands around the world," McCreless explained. Are rats more likely to cause bird extinctions on smaller, colder, or wetter islands than on other types of islands? Are native reptiles more vulnerable to the impacts of pigs than to those of rats or cats, and on what kinds of islands are these impacts seen most strongly? Answering such questions can help scientists understand the nuances of invasive mammal impacts on islands worldwide, and then use this information to direct limited resources to the places where management efforts will have the greatest benefits for native species. In the new paper, McCreless and colleagues fill in many of these knowledge gaps by analyzing the Threatened Island Biodiversity Database, a recently developed, global dataset of threatened native species and invasive mammals on islands. "We analyzed, for the first time at such a large scale, global patterns of island vertebrate extinctions in relation to different types of invasive mammals and physical island conditions," McCreless said. The study included more than 1,200 globally threatened or extinct vertebrate species that live (or lived) on more than 1,000 islands around the world. The authors found that just a few types of invasive mammals - rats, cats, pigs, mongooses, and weasels - are most strongly associated with the extirpation of native species (island-level extinction). Importantly, the study shows that the impacts of each mammal varied widely across both the type of native species being affected (native amphibians, birds, reptiles, or mammals) and the conditions of the islands on which they occurred. The authors used modeling approaches to predict how removing invasive mammals on different islands could reduce extinction risk for threatened species. In one of many examples, they showed that removing invasive mammals from small, dry islands could halve the extirpation risk for threatened native birds and mammals, but doing so on large, wet islands may have less benefit. "This kind of information is critical for conservationists trying to decide where to spend limited funds," said coauthor Donald Croll, professor of ecology and evolutionary biology at UC Santa Cruz. Finally, the paper highlights the global degree of the threat from invasive mammals on islands and the potential of management efforts to mitigate these threats. "We were able to estimate that up to 45 percent of globally threatened vertebrate populations on islands may be extirpated in the absence of conservation interventions, but that targeted invasive mammal control and eradication could prevent 41 to 75 percent of these predicted future extirpations," said McCreless. "That is critical knowledge for both conservationists and funders." Co-author Nick Holmes, science director of Island Conservation, said the study provides valuable guidance for conservation interventions by his and other groups. "This study is a valuable contribution for island restoration and conservation planning, and highlights the value of tackling invasive species challenges to prevent extinctions on islands," Holmes said.