scholarly journals Estimating the benefit of quarantine: eradicating invasive cane toads from islands

NeoBiota ◽  
2020 ◽  
Vol 60 ◽  
pp. 117-136
Author(s):  
Adam S. Smart ◽  
Reid Tingley ◽  
Ben L. Phillips
Keyword(s):  
Economic Value ◽  
Financial Benefit ◽  
Cane Toad ◽  
Modeling Framework ◽  
Density Estimates ◽  
Detection Probabilities ◽  
Containment Strategy ◽  
Negative Impacts ◽  
Study Sites ◽  
Removal Model

Islands are increasingly used to protect endangered populations from the negative impacts of invasive species. Quarantine efforts on islands are likely to be undervalued in circumstances in which a failure incurs non-economic costs. One approach to ascribe monetary value to such efforts is by modeling the expense of restoring a system to its former state. Using field-based removal experiments on two different islands off northern Australia separated by > 400 km, we estimate cane toad densities, detection probabilities, and the resulting effort needed to eradicate toads from an island. We use these estimates to conservatively evaluate the financial benefit of cane toad quarantine across offshore islands prioritized for conservation management by the Australian federal government. We calculate density as animals per km of freshwater shoreline, and find striking concordance of density estimates across our two island study sites: a mean density of 352 [289, 466] adult toads per kilometre on one island, and a density of 341 [298, 390] on the second. Detection probability differed between our two study islands (Horan Island: 0.1 [0.07, 0.13]; Indian Island: 0.27 [0.22, 0.33]). Using a removal model and the financial costs incurred during toad removal, we estimate that eradicating cane toads would, on average, cost between $22 487 [$14 691, $34 480] (based on Horan Island) and $39 724 [$22 069, $64 001] AUD (Indian Island) per km of available freshwater shoreline. We estimate the remaining value of toad quarantine across islands that have been prioritized for conservation benefit within the toads’ predicted range, and find the net value of quarantine efforts to be $43.4 [28.4–66.6] – $76.7 [42.6–123.6] M depending on which island dataset is used to calibrate the model. We conservatively estimate the potential value of a mainland cane toad containment strategy – to prevent the spread of toads into the Pilbara Bioregion – to be $80 [52.6–123.4] – $142 [79.0–229.0] M. We present a modeling framework that can be used to estimate the value of preventative management, via estimating the length and cost of an eradication program. Our analyses suggest that there is substantial economic value in cane toad quarantine efforts across Australian offshore islands and in a proposed mainland containment strategy.

scholarly journals Estimating the benefit of quarantine: eradicating invasive cane toads from islands

2018 ◽  
Author(s):  
Adam S Smart ◽  
Reid Tingley ◽  
Ben L Phillips
Keyword(s):  
Economic Value ◽  
List Type ◽  
Financial Benefit ◽  
Cane Toad ◽  
Modelling Framework ◽  
Detection Probabilities ◽  
Containment Strategy ◽  
Negative Impacts ◽  
Study Sites ◽  
Removal Model

SummaryIslands are increasingly used to protect endangered populations from the negative impacts of invasive species. Quarantine efforts are particularly likely to be undervalued in circumstances where a failure incurs non-economic costs. One approach to ascribe value to such efforts is by modeling the expense of restoring a system to its former state.Using field-based removal experiments on two very different islands off northern Australia separated by > 400 km, we estimate cane toad densities, detection probabilities, and the resulting effort needed to eradicate toads from an island, and use these estimates to examine the financial benefit of cane toad quarantine across offshore islands prioritized for conversation management by the Australian federal government.We calculate density as animals per km of freshwater shoreline, and find striking concordance of density across our two island study sites: a mean density of 353 [286, 446] individual toads per kilometer on one island, and a density of 366 [319, 343] on the second. Detection probability differed between the two islands.Using a removal model and the financial costs incurred during toad removal, we estimate that eradicating cane toads would, on average, cost between $9444 (based on Horan Island; high detectability) and $18093 AUD (Indian Island; low detectability) per km of available freshwater shoreline.Across islands that have been prioritized for conservation benefit within the toads’ predicted range, we provide an estimate of the value of toad quarantine on each island, and estimate the net value of quarantine efforts to be between $27.25 – $52.20 Million AUD. We explore a proposed mainland cane toad containment strategy – to prevent the spread of cane toads into the Pilbara Bioregion, and estimate its potential value to be between $33.79 – $64.74 M AUD.Synthesis and applications. We present a modelling framework that can be used to estimate the value of preventative management, via estimating the length and cost of an eradication program. Our analyses suggest that there is substantial economic value in cane toad quarantine efforts across Australian offshore islands and a proposed mainland toad containment strategy.

scholarly journals Variation in herpetofauna detection probabilities: implications for study design

2021 ◽  
Vol 193 (10) ◽  
Author(s):  
Jeremy A. Baumgardt ◽  
Michael L. Morrison ◽  
Leonard A. Brennan ◽  
Madeleine Thornley ◽  
Tyler A. Campbell
Keyword(s):  
Detection Probability ◽  
Relative Effectiveness ◽  
Population Monitoring ◽  
Occupancy Modeling ◽  
Pitfall Traps ◽  
Modeling Framework ◽  
Detection Probabilities ◽  
Study Sites ◽  
Sampling Duration ◽  
Biodiversity Decline

AbstractPopulation monitoring is fundamental for informing management decisions aimed at reducing the rapid rate of global biodiversity decline. Herpetofauna are experiencing declines worldwide and include species that are challenging to monitor. Raw counts and associated metrics such as richness indices are common for monitoring populations of herpetofauna; however, these methods are susceptible to bias as they fail to account for varying detection probabilities. Our goal was to develop a program for efficiently monitoring herpetofauna in southern Texas. Our objectives were to (1) estimate detection probabilities in an occupancy modeling framework using trap arrays for a diverse group of herpetofauna and (2) to evaluate the relative effectiveness of funnel traps, pitfall traps, and cover boards. We collected data with 36 arrays at 2 study sites in 2015 and 2016, for 2105 array-days resulting in 4839 detections of 51 species. We modeled occupancy for 21 species and found support for the hypothesis that detection probability varied over our sampling duration for 10 species and with rainfall for 10 species. For herpetofauna in our study, we found 14 and 12 species were most efficiently captured with funnel traps and pitfall traps, respectively, and no species were most efficiently captured with cover boards. Our results show that using methods that do not account for variations in detection probability are highly subject to bias unless the likelihood of false absences is minimized with exceptionally long capture durations. For monitoring herpetofauna in southern Texas, we recommend using arrays with funnel and pitfall traps and an analytical method such as occupancy modeling that accounts for variation in detection.

Manfaat Pemisahan Sampah Organik dan Anorganik Melalui Media Buku Ilustrasi Anak

2020 ◽  
Vol 5 (1) ◽  
Author(s):  
Sonde Martadireja
Keyword(s):  
Negative Impact ◽  
Positive Impact ◽  
Economic Value ◽  
Disease Clusters ◽  
Visual Communication Design ◽  
Second Stage ◽  
The Social ◽  
Children Health ◽  
Pile Up ◽  
Negative Impacts

<p><em>Garbage was defined as the residue of people's daily activities. In the social environment, to facilitate decomposition, garbage was generally grouped into two simple parts; namely organic garbage and inorganic garbage. </em><em>garbage management was needed to reduce the possibility of positive and negative impacts to the environment. Economic value was grouped into positive impact, while the source of odors and disease clusters were grouped as negative impact. </em><em>In this study, the focus of the problem is on the negative group. Because if garbage is allowed to pile up in one place in community settlements, it will become a source of unpleasant odors so that it can then become an area for germs to develop. </em><em>This condition is an indication that the garbage had not been managed properly and could worsen the surrounding environment. Therefore, proceeded from the scientific visual communication design, then at least hazard information and proper garbage processing method needed to be made. Knowledge of garbage separation to reduce environmental pollution would be better if known or understood since childhood. </em><em>The choice of work form for dissemination of this information was children illustration book. The process of realizing this illustration book work used several stages, the first stage was the process of collecting data about garbage and its processing, then data on the type of book that match the target audience. </em><em>The second stage was the process of making books, in this stage it went through several processes from pre-production to production.</em></p><p><em> </em></p><p><strong><em>Keywords:</em></strong><em> Illustration, Children, Health, Garbage</em><em></em></p>

Manfaat Pemisahan Sampah Organik dan Anorganik Melalui Media Buku Ilustrasi Anak

2021 ◽  
Vol 5 (1) ◽  
Author(s):  
Ardani Ari Suseno ◽  
Nabila Ulul Albab ◽  
Sonde Martadireja
Keyword(s):  
Negative Impact ◽  
Positive Impact ◽  
Economic Value ◽  
Disease Clusters ◽  
Visual Communication Design ◽  
Second Stage ◽  
Surrounding Environment ◽  
The Social ◽  
Pile Up ◽  
Negative Impacts

Garbage was defined as the residue of people's daily activities. In the social environment, to facilitate decomposition, garbage was generally grouped into two simple parts; namely organic garbage and inorganic garbage. garbage management was needed to reduce the possibility of positive and negative impacts to the environment. Economic value was grouped into positive impact, while the source of odors and disease clusters were grouped as negative impact. In this study, the focus of the problem is on the negative group. Because if garbage is allowed to pile up in one place in community settlements, it will become a source of unpleasant odors so that it can then become an area for germs to develop. This condition is an indication that the garbage had not been managed properly and could worsen the surrounding environment. Therefore, proceeded from the scientific visual communication design, then at least hazard information and proper garbage processing method needed to be made. Knowledge of garbage separation to reduce environmental pollution would be better if known or understood since childhood. The choice of work form for dissemination of this information was children illustration book. The process of realizing this illustration book work used several stages, the first stage was the process of collecting data about garbage and its processing, then data on the type of book that match the target audience. The second stage was the process of making books, in this stage it went through several processes from pre-production to production.

Indirect impacts of invasive cane toads (Bufo marinus) on nest predation in pig-nosed turtles (Carettochelys insculpta)

2006 ◽  
Vol 33 (5) ◽  
pp. 349 ◽  
Author(s):  
J. S. Doody ◽  
B. Green ◽  
R. Sims ◽  
D. Rhind ◽  
P. West ◽  
...  
Keyword(s):  
Nest Predation ◽  
Bufo Marinus ◽  
Cane Toad ◽  
Relative Population ◽  
Monitor Lizard ◽  
Before And After ◽  
Marked Decline ◽  
Study Sites ◽  
Indirect Impacts ◽  
One Year

The cane toad (Bufo marinus) was introduced into Australia in 1935. Because this toxic frog is novel to the Australian fauna, its introduction has impacted native fauna in a variety of ways. We anticipated a severe decline in the yellow-spotted monitor lizard (Varanus panoptes) associated with the arrival of cane toads along the Daly River, Northern Territory, and predicted a simultaneous impact on nest predation in the pig-nosed turtle (Carettochelys insculpta) because the lizard is the chief predator of C. insculpta eggs at the site. We surveyed for monitors and cane toads for five years at two sites before and after the arrival of cane toads, and surveyed for turtle nest predation for three years before, and one year after, the arrival of the toads. Collectively, our data and observations, combined with unpublished reports, indicate that: (1) cane toads arrived at our study sites during the wet seasons of 2003–04 and 2004–05; (2) the lizard V. panoptes readily succumbs to cane toad toxins; (3) . panoptes has experienced a marked decline in relative population numbers coincident with the arrival of the toads at the site; and (4) V. panoptes has been reduced to such low numbers that it is currently no longer a significant predator of pig-nosed turtle eggs.

scholarly journals Estimating Detection Probability and Density from Point-Count Surveys: A Combination of Distance and Double-Observer Sampling

The Auk ◽  
2006 ◽  
Vol 123 (3) ◽  
pp. 735-752 ◽  
Author(s):  
Michelle L. Kissling ◽  
Edward O. Garton
Keyword(s):  
Detection Probability ◽  
Survey Methods ◽  
Effective Area ◽  
Survey Method ◽  
Density Estimates ◽  
Point Count ◽  
Detection Probabilities ◽  
Fixed Radius ◽  
Count Surveys ◽  
Double Observer

Abstract Point counts are the method most commonly used to estimate abundance of birds, but they often fail to account properly for incomplete and variable detection probabilities. We developed a technique that combines distance and double-observer sampling to estimate detection probabilities and effective area surveyed. We applied this paired-observer, variable circular-plot (POVCP) technique to point-count surveys (n = 753) conducted in closed-canopy forests of southeast Alaska. Distance data were analyzed for each species to model a detection probability for each observer and calculate an estimate of density. We then multiplied each observer's density estimates by a correction factor to adjust for detection probabilities <1 at plot center. We compared analytical results from four survey methods: single-observer fixed-radius (50-m) plot; single-observer, variable circular-plot (SOVCP); double-observer fixed-radius (50-m) plot; and POVCP. We examined differences in detection probabilities at plot center, effective area surveyed, and densities for five bird species: Pacific-slope Flycatcher (Empidonax difficilis), Winter Wren (Troglodytes troglodytes), Golden-crowned Kinglet (Regulus satrapa), Hermit Thrush (Catharus guttatus), and Townsend's Warbler (Dendroica townsendi). Average detection probabilities for paired observers increased ≈8% (SE = 2.9) for all species once estimates were corrected for birds missed at plot center. Density estimators of fixed-radius survey methods were likely negatively biased, because the key assumption of perfect detection was not met. Density estimates generated using SOVCP and POVCP were similar, but standard errors were much lower for the POVCP survey method. We recommend using POVCP when study objectives require precise estimates of density. Failure to account for differences in detection probabilities and effective area surveyed results in biased population estimators and, therefore, faulty inferences about the population in question. Estimaciones de la Densidad y de las Probabilidades de Detección a Partir de Muestreos Utilizando Conteos en Puntos: Una Combinación de Muestreos de Distancia y de Doble Observador

The uneasy coexistence between Carpet Pythons and Cane Toads

2020 ◽  
Author(s):  
Gregory P. Brown ◽  
Jeremy Hemphill ◽  
Richard Shine
Keyword(s):  
Negative Impact ◽  
Prey Type ◽  
Direct Costs ◽  
Cane Toad ◽  
Predator Species ◽  
Indirect Benefits ◽  
Negative Impacts ◽  
Monitor Lizards ◽  
A Site ◽  
Free Ranging

We describe a case of a free-ranging Carpet Python Morelia spilota consuming a toxic Cane Toad Rhinella marina, and dying as a result. Such an encounter would not be surprising at the toad invasion front, where predators first confront this novel prey type. However, the encounter we describe occurred at a site near Darwin where toads have been present for fifteen years. Other reports suggest that the behaviour we observed occurs across the snake’s range. Lethal ingestion of toads has been suggested to threaten the viability of populations of Carpet Pythons, but paradoxically, our surveys at this site reveal a twofold increase in abundance of Carpet Pythons since the arrival of toads. Toad invasion likely has favoured pythons by reducing the abundance of large monitor lizards, that are both predators and competitors of Carpet Pythons. That advantage has outweighed occasional cases where a snake is fatally poisoned by consuming a toad. Thus, the overall impact of Cane Toads on Carpet Pythons (and likely, other predator species) is a balance between direct costs and indirect benefits. Negative impacts on individuals may not necessarily translate to a negative impact on the species.

scholarly journals Bringing clarity to the clouded leopard Neofelis diardi: first density estimates from Sumatra

Oryx ◽  
2014 ◽  
Vol 48 (4) ◽  
pp. 536-539 ◽  
Author(s):  
Rahel Sollmann ◽  
Matthew Linkie ◽  
Iding A. Haidir ◽  
David W. Macdonald
Keyword(s):  
Mixed Forest ◽  
Camera Trap ◽  
Forest Loss ◽  
Data Sets ◽  
Panthera Tigris ◽  
Density Estimates ◽  
Clouded Leopard ◽  
Data Limitations ◽  
Capture Recapture ◽  
Study Sites

AbstractWe use data from camera-trap surveys for tigers Panthera tigris in combination with spatial capture–recapture models to provide the first density estimates for the Sunda clouded leopard Neofelis diardi on Sumatra. Surveys took place during 2004–2007 in the Kerinci landscape. Densities were 0.385–1.278 per 100 km2. We found no statistically significant differences in density among four study sites or between primary and mixed forest. Because the data sets are too small to account for differences in detection parameters between sexes, density is probably underestimated. Estimates are comparable to previous estimates of 1–2 per 100 km2 from the lowlands of central Sabah, on Borneo. Data limitations suggest that camera-trap surveys for Sunda clouded leopards require traps spaced more closely, to increase the chance of recaptures at different traps. Nevertheless, these first density estimates for clouded leopards on Sumatra provide a benchmark for measuring future conservation impact on an island that is undergoing rapid forest loss.

Oachira Panthrandu Vilakku

2015 ◽  
Vol 7 (4) ◽  
pp. 403-416 ◽  
Author(s):  
Vimal Babu ◽  
Sandeep Munjal
Keyword(s):  
Design Methodology ◽  
Economic Value ◽  
Economic Benefits ◽  
Policy Changes ◽  
Multiple Stakeholders ◽  
Content Type ◽  
Local Residents ◽  
Negative Impacts ◽  
The Town ◽  
Practical Implications

Purpose – This study aims to investigate how Oachira Panthrandu Vilakku (twelve-lamp) festival in Oachira helps in providing economic benefits to local residents of the town during the pilgrimage season. Design/methodology/approach – Stakeholder interviews and focus-group roundtable discussions with multiple stakeholders were conducted. Findings – Policy changes have been studied and recommended for enhancing the economic value of the culturally embedded Panthrandu Vilakku festival celebrated in Oachira, Kerala, India. Practical implications – There is huge untapped potential for India’s festivals in India. While efforts are made to leverage these for economic gains, the negative impacts also need to be recognized and mitigated. Originality/value – The study is significant in the context of arresting economic leakage and promoting an ecosystem of decision-making at community level by the local residents.

Density estimates of cane toads from native populations based on mark-recapture data

1996 ◽  
Vol 23 (3) ◽  
pp. 305 ◽  
Author(s):  
M Lampo ◽  
P Bayliss
Keyword(s):  
Air Temperature ◽  
Native Species ◽  
Population Estimates ◽  
Cane Toad ◽  
Potential Threat ◽  
Density Estimates ◽  
Mark Recapture ◽  
Climate Conditions ◽  
Wide Range ◽  
Native Populations

The cane toad (Bufo marinus) has received considerable attention because of its rapid spread in Australia and the potential threat it may represent to native species. Although the introduction of pathogens from native populations is now being considered to control this species, population estimates based on comparable methods that demonstrate that native populations are in fact less dense than the introduced ones are not available. Accurate population estimates are necessary to evaluate potential techniques for the control of the cane toad. We estimated population densities of cane toads over a wide range of habitat types and climate conditions by means of mark-recapture data. The capture history and location of toads each night were analysed to explore the validity of some of the assumptions of mark-recapture models. Because migrations, deaths and recruitment over three nights appear to be unimportant, populations may be legitimately regarded as closed for that period. However, cane toads seem highly sensitive to disturbance effects due to trapping andlor handling. Consequently, density estimates based on removal methods seem the most reliable because they are not sensitive to handling and trapping effects. Similarly, analyses of residuals of regressions between 1-night counts and density estimates suggested that toad nightly activity is affected by the air temperature during sampling. However, only 60% of the variation in estimated densities can be predicted by 1-night counts and air temperature. Estimates of population density over a wide range of habitats in South America were one order of magnitude lower than estimates in Australia. We speculate on the possible factors that may account for the lower densities in populations in the native range of the species.

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