Elsa Bonnaud

Invasive mammal eradication on islands results in substantial conservation gains.

Significance Global conservation actions to prevent or slow extinctions and protect biodiversity are costly. However, few conservation actions have been evaluated for their efficacy globally, hampering the prioritization of conservation actions. Islands are key areas for biodiversity conservation because they are home to more than 15% of terrestrial species and more than one-third of critically endangered species; nearly two-thirds of recent extinctions were of island species. This research quantifies the benefits to native island fauna of removing invasive mammals from islands. Our results highlight the importance of this conservation measure for protecting the worlds most threatened species. More than US

Feral Cats and Biodiversity Conservation: The Urgent Prioritization of Island Management

21 billion is spent annually on biodiversity conservation. Despite their importance for preventing or slowing extinctions and preserving biodiversity, conservation interventions are rarely assessed systematically for their global impact. Islands house a disproportionately higher amount of biodiversity compared with mainlands, much of which is highly threatened with extinction. Indeed, island species make up nearly two-thirds of recent extinctions. Islands therefore are critical targets of conservation. We used an extensive literature and database review paired with expert interviews to estimate the global benefits of an increasingly used conservation action to stem biodiversity loss: eradication of invasive mammals on islands. We found 236 native terrestrial insular faunal species (596 populations) that benefitted through positive demographic and/or distributional responses from 251 eradications of invasive mammals on 181 islands. Seven native species (eight populations) were negatively impacted by invasive mammal eradication. Four threatened species had their International Union for the Conservation of Nature (IUCN) Red List extinction-risk categories reduced as a direct result of invasive mammal eradication, and no species moved to a higher extinction-risk category. We predict that 107 highly threatened birds, mammals, and reptiles on the IUCN Red List—6% of all these highly threatened species—likely have benefitted from invasive mammal eradications on islands. Because monitoring of eradication outcomes is sporadic and limited, the impacts of global eradications are likely greater than we report here. Our results highlight the importance of invasive mammal eradication on islands for protecting the worlds most imperiled fauna.

The 100th of the world’s worst invasive alien species

A great part of the Earths biodiversity occurs on islands, to which humans have brought a legion of invasive species that have caused population declines and even extinctions. The domestic cat is one of the most damaging species introduced to islands, being a primary extinction driver for at least 33 insular endemic vertebrates. Here, we examine the role of feral cats in the context of the island biodiversity crisis, by combining data from reviews of trophic studies, species conservation status reports, and eradication campaigns. The integration of these reviews permits us to identify priority islands where feral cat eradications are likely to be feasible and where cats are predicted to cause the next vertebrate extinctions. Funding agencies and global conservation organizations can use these results to prioritize scarce conservation funds, and national and regional natural resource management agencies can rank their islands in need of feral cat eradication within a global context.

Invasion Biology: Specific Problems and Possible Solutions

Abstract Biological invasions are among the greatest threats to global biodiversity, but in contrast to most other global threats, they suffer from specific communication issues. Our paper presents the first new addition to the widely cited IUCN list of “100 of the world’s worst invasive species”, a list created a decade ago in response to these communication issues. We briefly present this list, the recent removal of one species from that list, and the rationale to include a novel, 100th species to replace it. The new species of this list, giant salvinia (Salvinia molesta), was chosen by the community of invasion biologists (over 650 experts from over 60 countries). This new addition to the list will draw public attention to the damage caused by invasive alien species and it will help stimulate the necessary discussion of this critical issue in science and policy circles.

Importance of lethal control of invasive predators for island conservation

Biological invasions have been unambiguously shown to be one of the major global causes of biodiversity loss. Despite the magnitude of this threat and recent scientific advances, this field remains a regular target of criticism - from outright deniers of the threat to scientists questioning the utility of the discipline. This unique situation, combining internal strife and an unaware society, greatly hinders the progress of invasion biology. It is crucial to identify the specificities of this discipline that lead to such difficulties. We outline here 24 specificities and problems of this discipline and categorize them into four groups: understanding, alerting, supporting, and implementing the issues associated with invasive alien species, and we offer solutions to tackle these problems and push the field forward.

The unnoticed effect of a top predator on complex mutualistic ecological interactions

James C. Russell,∗† Holly P. Jones,‡ Doug P. Armstrong,§ Franck Courchamp,∗∗ Peter J. Kappes,†† Philip J. Seddon,‡‡ Steffen Oppel,§§ Mark J. Rauzon,∗∗∗ Phil E. Cowan,††† Gerard Rocamora,† Piero Genovesi,‡‡‡ Elsa Bonnaud,∗∗ Bradford S. Keitt,§§§ Nick D. Holmes,§§§ and Bernie R. Tershy∗∗∗∗ ∗School of Biological Sciences, University of Auckland, Private Bag 92019, Auckland, 1142, New Zealand, email j.russell@auckland.ac.nz †Island Biodiversity & Conservation Center, University of Seychelles, P.O. Box 1348, Anse Royale, Republic of Seychelles ‡Department of Biological Sciences and Institute for the Study of the Environment, Northern Illinois University, DeKalb, IL 60115, U.S.A. §Wildlife Ecology Group, Institute of Natural Resources, Massey University, Private Bag 11 222, Palmerston North 4442, New Zealand ∗∗Ecologie Systematique Evolution, Universite Paris-Sud, CNRS, AgroParisTech, Universite Paris-Saclay, 91400 Orsay, France ††Oregon Cooperative Fish and Wildlife Research Unit, Department of Fisheries and Wildlife, Oregon State University, Corvallis, OR 97331, U.S.A. ‡‡Department of Zoology, University of Otago, P.O. Box 56, Dunedin 9054, New Zealand §§RSPB Centre for Conservation Science, Royal Society for the Protection of Birds, The Lodge, Sandy, Bedfordshire SG19 2DL, United Kingdom ∗∗∗Geography Department, Laney College, Oakland, CA 94607, U.S.A. †††Landcare Research, P.O. Box 69040, Lincoln 7640, New Zealand ‡‡‡Institute for Environmental Protection and Research, Via V. Brancati 48, Rome I-00144, Italy §§§Island Conservation, 2161 Delaware Avenue Suite A, Santa Cruz, CA 95060, U.S.A. ∗∗∗∗University of California Santa Cruz, 100 Shaffer Road, Santa Cruz, CA 95060, U.S.A.

A global review of the impacts of invasive cats on island endangered vertebrates

Abstract Vertebrates often mediate seed dispersal systems, essential for the maintenance of biodiversity. Some of these acquire a complex multistep process in island environments, where for example a native predatory bird can predate upon a frugivorous vertebrate, dispersing seeds secondarily. These complex mutualistic processes are really threatened by biological invasions especially on islands, due to the particular and intrinsic traits of their biotas. One of the most pernicious invasive mammals is the feral cat, widely introduced on at least 179,000 islands worldwide. Despite the potential impact of disruption of these complex seed dispersal processes, their ecological effects remain largely unknown. Therefore, the main aim of this contribution is to assess the impact of an invasive vertebrate on seed dispersal effectiveness at the crucial phases of plant recruitment: seed damage, viability, and germination. We designed a laborious captivity experiment with lizards and cats to simulate the four potential ways seeds could be dispersed in the wild: (1) control plants, (2) lizard droppings, (3) cat droppings and (4) cat droppings after consuming frugivorous lizards. We considered those four plant species whose seeds were the most abundant in feral cat droppings in all the main habitats of the Canary Islands. The main results indicated that (1) species with thicker seed coat better resisted abrasion caused by the digestive effect of the invasive cats and, (2) native and endemic species with thinner seed coats, that have not evolved with invasive mammals, suffered from a negative effect on seed effectiveness. To our knowledge, this is the first study reporting the potential disruptive impact of secondary seed dispersal systems caused by an invasive predator and one of the scant contributions evaluating seed dispersal effectiveness.