Five years of conserving the ‘world's rarest snake’, the Antiguan racer Alsophis antiguae

Daltry, Jenny C.; Bloxam, Quentin; Cooper, Gail; Day, Mark L.; Hartley, J. P.; Henry, McRonnie; Lindsay, Kevel; Smith, Brian E.

doi:10.1017/s0030605300031677

Cited by 10 publications

(13 citation statements)

References 10 publications

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“…Further, we excluded several countries where few invasive mammal eradications have occurred (e.g., 36, 37), although there are documented responses in other countries that are worth noting. For example, rat eradication was undertaken on Great Bird Island, an islet off Antigua in the Lesser Antilles, which houses the only population of world's rarest snake, the critically endangered Antiguan racer (Alsophis antiguae) (36). The outcome has been highly successful, with the Antiguan racer population increasing 20-fold on four islands (38).…”

Section: Resultsmentioning

confidence: 99%

Invasive mammal eradication on islands results in substantial conservation gains

Jones

Holmes²,

Butchart

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

414

379

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More than US$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 world's most imperiled fauna.conservation | restoration | invasive species | island | eradication T he rate of global species decline and extinction is rapid and likely to increase (1-4), although at least US$21.5 billion is spent annually worldwide on conservation of biodiversity (5). Improving conservation outcomes has focused largely on highlevel increases in efficiency, including the distribution of funding across countries (5), or on identifying the ecoregions, habitats, and species most in need (6). Although great strides have been made in promoting evidence-based conservation (7), systematic evaluations of the effectiveness of different actions taken to protect biodiversity at the global scale are rare, with the exception of protected areas (8).Islands occupy ∼5.5% of the terrestrial surface area but contain more than 15% of terrestrial species (9), 61% of all recently extinct species, and 37% of all critically endangered species on the International Union of the Conservation of Nature (IUCN) Red List (10). Invasive nonnative mammals (hereafter, "invasive mammals") are the main cause of animal extinctions on islands and are one of the most important threats to remaining insular biodiversity (10-12). Eradicating invasive mammals from islands is an increasingly common conservation tool and has been ...

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Section: Resultsmentioning

confidence: 99%

Invasive mammal eradication on islands results in substantial conservation gains

Jones

Holmes²,

Butchart

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

414

379

View full text Add to dashboard Cite

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“…The racers were regarded as extinct until their rediscovery on 9.9 ha Great Bird Island in the early 1960s. However, ship rats had reached this island and more than 50% of the remaining 51 racers showed scarring consistent with rat bites (Daltry et al 2001). Eight years after rats were eradicated from Great Bird Island in 1995, the racer population had at least doubled, scarring from bites was reduced to 5% and became confined to large, old individuals (Daltry et al 2003).…”

Section: Antiguan Racer-ship Rat Interactions In the West Indiesmentioning

confidence: 94%

“…Ship rats have subsequently been eradicated from 12 additional islands and the racers re-introduced to two of them. As a byproduct of these eradications, vegetation biomass and diversity increased (Daltry et al 2001), redbilled tropic birds (Phaeton aetherecus) doubled in number (Ross 2000), and reproductive output of West Indian whistling ducks (Dendrocygna arborea) also increased (Daltry et al 2001). …”

Section: Antiguan Racer-ship Rat Interactions In the West Indiesmentioning

confidence: 96%

Have the Harmful Effects of Introduced Rats on Islands been Exaggerated?

2006

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Introduced rats are now being eradicated from many islands. Increasingly, these eradications are contested by activists claiming moral, legal, cultural, historic or scientific reasons and poorly documented evidence of effects. We reviewed the global literature on the effects of rats on island flora and fauna. We then used New Zealand as a case study because of its four-decade history of rat eradications and many detailed and innovative studies of how rats affect native species. These include use of exclosures, local manipulations of rat populations, video surveillance, and measurements of responses following eradications. The most intensive studies have been on the Pacific rat (Rattus exulans), a small South-East Asian species spread by Polynesians throughout the Pacific. These and the more recently introduced Norway rat (R. norvegicus) and ship (roof) rat (R. rattus) suppress some forest plants, and are associated with extinctions or declines of flightless invertebrates, ground-dwelling reptiles, land birds, and burrowing seabirds. On islands off France, Norway rats are also implicated in declines of shrews. Globally, ship rats were associated with declines or extinctions of the largest number of indigenous vertebrate species (60), including small mammals such as deer mice and bats. Effects of rats on forest trees and seabird populations are sufficiently pervasive to affect ecosystem structure and function. However, the data are patchy. Deficiencies in our knowledge would be reduced by documenting distribution and abundance of indigenous species before and after eradications. Comprehensive measurements of the responses of indigenous species to rat eradications would enable the development of testable models of rat invasion effects.

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“…They are present on most islands off New Zealand, Australia, Indonesia, Polynesia, Madagascar, in the subantarctic and other groups of high biodiversity. Currently present in most insular locations, rats are major predators of birds, reptiles and arthropods (Atkinson 1985;Cree et al 1995;Palmer & Pons 1996;Towns et al 1997;Daltry et al 2001;Towns et al 2001;Towns et al 2006). They are omnivorous and eat seeds, stems, fruits and leaves of many plant species (Campbell & Atkinson 1999;Williams et al 2000;Campbell & Atkinson 2002).…”

Section: Introductionmentioning

confidence: 99%

Rats dying for mice: Modelling the competitor release effect

Caut¹,

et al. 2007

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Introduced vertebrate predators are one of the most important threats to endemic species throughout a range of ecosystems, in particular on islands in biodiversity hot spots. Consequently, the reduction of predator numbers is considered a key conservation action in the management of many native vertebrates vulnerable to predators. It is now established that control attempts may affect non-target species through trophic interactions, but little is known concerning their consequences on competitive relationships. We study a mathematical model mimicking the effects of controlling introduced species in the presence of their competitors.We used two competing rodents to illustrate our study: black rats, Rattus rattus, and mice, Mus musculus. Analyses of the model show that control of only one introduced species logically results in the dramatic increase of the overlooked competitor. We present empirical data that confirm our theoretical predictions. Less intuitively, this process, which we term 'the competitor release effect', may also occur when both introduced competitors are simultaneously controlled. In our setting, controlling both predators can promote their coexistence. This occurs as soon as the inferior competitor benefits from the differential effect of the simultaneous control of both competitors, that is, when the indirect positive effect of control (the removal of their competitors) exceeds its direct negative effect (their own removal). Both control levels and target specificity have a direct influence on the extent of this process: counter-intuitively, the stronger and more specific the control, the greater the effect. The theoretical validation of the competitor release effect has important implications in conservation, especially for control management.

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Five years of conserving the ‘world's rarest snake’, the Antiguan racer Alsophis antiguae

Cited by 10 publications

References 10 publications

Invasive mammal eradication on islands results in substantial conservation gains

Invasive mammal eradication on islands results in substantial conservation gains

Have the Harmful Effects of Introduced Rats on Islands been Exaggerated?

Rats dying for mice: Modelling the competitor release effect

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