Rapid eradication of feral pigs (Sus scrofa) from Santa Cruz Island, California

Parkes, John; Ramsey, David S. L.; Macdonald, Norman; Walker, Kelvin; McKnight, Sean; Cohen, Brian S.; Morrison, Scott

doi:10.1016/j.biocon.2009.11.028

Cited by 96 publications

(111 citation statements)

References 16 publications

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“…Barr et al 2011), new toxins (Eason et al 2014), baits (Johnston et al 2013) and delivery devices (e.g. Blackie et al 2013), and new ways of using dogs and hunters to control ungulates (Parkes et al 2010). Inventors may promote their devices as solutions for large-scale pest management but none as yet appear likely to be as effective or efficient as aerial baiting against the ubiquitous species across large areas, and none yet (to our knowledge) are able to achieve 100% reductions in the target populations in the short time period and over sufficiently large areas essential in efforts to eradicate rapidly-reproducing species such as rodents.…”

Section: Control Toolsmentioning

confidence: 99%

“…Trends in eradication tactics have been: (i) better training and use of dogs fitted with GPS collars to assist with ungulate eradication (Parkes et al 2010); (ii) development of analytical systems to validate success for species reduced to zero by a series of control events (Ramsey et al 2009) and for rodents after one-hit aerial baiting (Samaniego-Herrera et al 2013); (iii) deliberate targeting of sympatric species with aerial baiting for rodents, i.e. by-kill of some of the predators followed by ground control to remove survivors (Griffiths et al 2015); and (iv) a growing intent to tackle islands inhabited by people (Glen et al 2013a).…”

Section: Control Of Possums As Vectors Of Bovine Tuberculosismentioning

confidence: 99%

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Past, present and two potential futures for managing New Zealand’s mammalian pests

Parkes¹,

Nugent

Forsyth

et al. 2017

NZ J Ecol

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Abstract:In 2003, a review of how introduced mammals were managed as pests in New Zealand was published. Since then trends for the control of these mammals include moves from pest-by-pest prioritisation towards site-based and multiple-pest management, extension of large-scale aerial control of predators to include beech forests, increasing intensive management of sites by private and non-government agencies, and increasing effort by regional councils and managers of vectors of bovine tuberculosis. The current deployment is the sum of largely independent decisions made by different agencies and individuals with different priorities. National agencies might optimise their own decisions, but overall deployment will always be nationally suboptimal when objectives are set at regional or local scales. This system includes both small areas where most of the mammals present are managed intensively and large areas where fewer species are managed. We discuss how this deployment might evolve as a network of smaller core areas aiming to achieve zero or low densities of all or most pests, with surrounding halos with lesser control effort against fewer species, enough to allow for at least 'safe passage' of native animals between the cores. This system might work best along the more-or-less contiguous native habitats along the axial ranges of the North and South Islands, especially if agencies with a national mandate are prepared to act in the extensive areas between core sites. Some have asked whether the successful eradication of mammals on small islands can be scaled up to the main islands of New Zealand. The current version of this predator-free model aims at the ubiquitous ship rat, brushtail possum and stoat. A key need for the predator-free model is a tool that kills 100% of each of the three main target species, ideally with one large-scale, socially-acceptable application. Without this tool the cost to find and kill survivors would raise the costs of national eradication to about $32 billion, assuming current costs of multiple-species eradications on islands. For sustained control options, research is needed to inform the frequency and intensity of control, and thus the best control tools. The ability to detect target pests at low densities and management of reinvasion are essential for achieving zero or low pest density goals. We suggest that the core/halo model of pest management, within a network of assets to be protected, will best protect New Zealand's biodiversity for the foreseeable future. The national scale pest-or predator-free aspiration is not currently (and may never be) feasible and risks diverting resources from more optimal solutions, as occurred with the 'last rabbit' and 'last deer' programmes promoted last century.

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Section: Control Toolsmentioning

confidence: 99%

Section: Control Of Possums As Vectors Of Bovine Tuberculosismentioning

confidence: 99%

Past, present and two potential futures for managing New Zealand’s mammalian pests

Parkes¹,

Nugent

Forsyth

et al. 2017

NZ J Ecol

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“…Slopes tend to have either a north-facing aspect with dense chaparral woodland dominated by scrub oaks (Quercus pacifica) and Ceanothus spp., or a south-facing aspect with woody vegetation interspersed by grass and Artemisia spp. (Parkes et al 2010). From the 1840s until the 1980s, the island was managed as a livestock ranch.…”

Section: Study Sitementioning

confidence: 99%

Hierarchical distance‐sampling models to estimate population size and habitat‐specific abundance of an island endemic

Sillett

Chandler

Royle

et al. 2012

Ecological Applications

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118

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Abstract. Population size and habitat-specific abundance estimates are essential for conservation management. A major impediment to obtaining such estimates is that few statistical models are able to simultaneously account for both spatial variation in abundance and heterogeneity in detection probability, and still be amenable to large-scale applications. The hierarchical distance-sampling model of J. A. Royle, D. K. Dawson, and S. Bates provides a practical solution. Here, we extend this model to estimate habitat-specific abundance and rangewide population size of a bird species of management concern, the Island Scrub-Jay (Aphelocoma insularis), which occurs solely on Santa Cruz Island, California, USA. We surveyed 307 randomly selected, 300 m diameter, point locations throughout the 250-km 2 island during October 2008 and April 2009. Population size was estimated to be 2267 (95% CI 1613-3007) and 1705 (1212-2369) during the fall and spring respectively, considerably lower than a previously published but statistically problematic estimate of 12 500. This large discrepancy emphasizes the importance of proper survey design and analysis for obtaining reliable information for management decisions. Jays were most abundant in low-elevation chaparral habitat; the detection function depended primarily on the percent cover of chaparral and forest within count circles. Vegetation change on the island has been dramatic in recent decades, due to release from herbivory following the eradication of feral sheep (Ovis aries) from the majority of the island in the mid-1980s. We applied best-fit fall and spring models of habitat-specific jay abundance to a vegetation map from 1985, and estimated the population size of A. insularis was 1400-1500 at that time. The 20-30% increase in the jay population suggests that the species has benefited from the recovery of native vegetation since sheep removal. Nevertheless, this jay's tiny range and small population size make it vulnerable to natural disasters and to habitat alteration related to climate change. Our results demonstrate that hierarchical distance-sampling models hold promise for estimating population size and spatial density variation at large scales. Our statistical methods have been incorporated into the R package unmarked to facilitate their use by animal ecologists, and we provide annotated code in the Supplement.

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“…While there are no clear links between the neighborhood distance (1200 m, *450 ha; Fig. 5e) and known processes, this scale is in the same realm as the approximate home ranges of the island's now eradicated feral pigs (290 ± 125 ha; unpublished data, cited in Parkes et al 2010) and at the lower end of the range of published feral pig home range sizes globally (Saunders and McLeod 1999). Feral pigs can have major impacts on ecosystem assembly, both through seed predation and through rooting (Parkes et al 2010), which could potentially have an impact on the quality and structure of the vegetation in this height class.…”

Section: Spatial Autocorrelationmentioning

confidence: 98%

“…E neighborhood distance in tall NDVI model. F average home range of feral pigs on SCI (Parkes et al 2010) Fig. 6 Bars proportional to the fraction of the variation explained by the final simultaneous autoregressive model components.…”

Section: The Importance Of Environmental Conditionsmentioning

confidence: 99%

Linking vegetation patterns to environmental gradients and human impacts in a mediterranean-type island ecosystem

2014

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Vegetation patterns at the landscape scale are shaped by myriad processes and historical events, and understanding the relative importance of these processes aids in predicting current and future plant distributions. To quantify the influence of different environmental and anthropogenic patterns on observed vegetation patterns, we used simultaneous autoregressive modeling to analyze data collected by the Carnegie Airborne Observatory over Santa Cruz Island (SCI; California, USA). SCI is a large continental island, and its limited suite of species and well documented land use history allowed us to consider many potential determinants of vegetation patterns, such as topography, substrate, and historical grazing intensity. As a metric of vegetation heterogeneity, we used the normalized difference vegetation index (NDVI) stratified into three vegetation height classes using LiDAR (short, medium, and tall). In the SAR models topography and substrate type were important controls, together explaining 8-15 % of the total variation in NDVI, but historical grazing and spatial autocorrelation were also key components of the models, together explaining 17-21 % of the variation in NDVI. Optimal spatial autocorrelation distances in the short and medium height vegetation models (600-700 m) were similar to the home range sizes of two crucial seed dispersers on the island-the island fox (Urocyon littoralis santacruzae) and the island scrub-jay (Aphelocoma insularis)-suggesting that these animals may be important drivers of the island's vegetation patterns. This study highlights the importance of dynamic processes like dispersal limitation and disturbance history in determining presentday vegetation patterns.

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Rapid eradication of feral pigs (Sus scrofa) from Santa Cruz Island, California

Cited by 96 publications

References 16 publications

Past, present and two potential futures for managing New Zealand’s mammalian pests

Past, present and two potential futures for managing New Zealand’s mammalian pests

Hierarchical distance‐sampling models to estimate population size and habitat‐specific abundance of an island endemic

Linking vegetation patterns to environmental gradients and human impacts in a mediterranean-type island ecosystem

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