Lethal Control Research Articles

Perspective: Why might removing carnivores maintain or increase risks for domestic animals?

Human-carnivore conflict is still characterized by lethal control, even while some evidence suggests that carnivore removal may not affect the likelihood of future livestock predation, or that it may even exacerbate the problem. Here we propose five non-exclusive, and likely additive, hypotheses for why lethal removals could fail to mitigate livestock-carnivore conflict. We also propose a methodological change in the scale of conflict analyses from populations to smaller social networks, and encourage public education that includes discussions about the potential consequences for communities with livestock following the killing of carnivores, in addition to broader outreach about both the costs and benefits of living with carnivores.

Mesopredator release among invasive predators: Controlling red foxes can increase feral cat density and alter their behaviour

Abstract1. The mesopredator release theory predicts that the density of subordinate predators will increase as dominant predators decline. Persistent debate around mesopredator release in part reflects the lack of robust, replicated experiments that test this theory, and the use of population indices that confound changes in mesopredator density and detectability. This uncertainty has immediate impacts for conservationists who are faced with managing sympatric invasive predators.2. We used replicated experimental designs and spatially explicit models to examine whether mesopredator release of the feral cat Felis catus occurs in response to targeted control of the introduced red fox Vulpes vulpes. We surveyed three Control‐Impact paired landscapes in a region with long‐term fox control (1080 poison baiting) and conducted a Before‐After Control‐Impact Paired‐Series experiment in another region. We used fox occurrence as a simple metric of fox populations and estimated feral cat density with spatial mark–resight models.3. Lethal fox control had varying effects on fox occurrence, consistent with variation in the duration and intensity of poison baiting. Correspondingly, responses in feral cat density ranged from negligible to a 3.7‐fold higher density in fox‐baited landscapes. At a fine spatial scale (200 m2), feral cat density was negatively associated with fox occurrence probability across both regions. These results were consistent with mesopredator release, although uncertainty was high in the region where fox control had only recently commenced.4. Feral cat detectability also varied across the (artificially manipulated) gradients of fox occurrence probability. In one region, nonlinear models indicated that feral cats had lower detection and increased movement rates when foxes were uncommon, giving way to density suppression at high fox occurrence probabilities.5. Synthesis and applications. Our study provides replicated, experimental evidence that dominant predator suppression can be associated with a higher mesopredator density. Mesopredator release can manifest as changes in both behaviour and density, distorting inference if these processes are not distinguished. Our results may help explain why fox control does not consistently improve native prey persistence, suggesting integrated pest management may be necessary to improve conservation outcomes.

Increased grey wolf diurnality in southern Europe under human-restricted conditions.

Wolves have been the archetype of wildlife persecution by humans for centuries all over the world, and still are heavily persecuted in some regions. Facultative diurnal/nocturnal wild mammals are known to become more nocturnal when persecuted. Conversely, little is known regarding the possibility of wolves becoming more diurnal if not persecuted. We took advantage of a 9-year natural experiment of restricted human access to a restored coal mine debris dump to study the daily activity patterns of wolves under conditions of infrequent human presence. Results were compared with a paired control site with frequent human use. Circadian wolf activity was monitored using camera traps (3 years in human-restricted site; 2 years in control). Additionally, data from two GPS-GSM-collared wolves monitored in a second control site were also analyzed. In our control sites, wolves were nearly inactive during daylight hours. In contrast, in the human-restricted site wolves extended their activity toward noon, with a daily activity peak between 10:00 and 12:00, and showed some activity throughout the entire circadian 2-h interval cycle considered. Wolves clearly had higher diurnality in the human-restricted area with 78% greater incidence of capture with remote cameras during the day than in the control site. We suggest that the shift toward increased diurnality was related to the loss of fear of humans. Evidence in support of this hypothesis comes from flight initiation distance (FID) data. Wolves showed relatively short FIDs when faced with a human observer (range 70-183 m) in broad daylight at the human-restricted site, but were so afraid of humans in the control site that we were unable to conduct FID trials there. Based on these results, we suggest that wolves may increase their diurnality in those European countries with currently increasing movement of human populations from rural to urban areas and that do not conduct lethal control of wolves. This would represent a historical landmark for a species that has been persecuted for many centuries. However, such behavioral shifts could bring new human-wolf conflicts that would require new policies.

Monitoring methaemoglobinaemia in birds using 5μL of whole blood.

Methaemoglobin (MetHb) forming compounds such as para-aminopropiophenone (PAPP) and sodium nitrite (NaNO2) have recently been adopted for the lethal control of a range of invasive carnivores and mustelids. Determining the relative hazard of these compounds to non-target bird species is an important component of ecological risks evaluation. Problematically, some potential non-target bird species may be as small as 10 g in body mass, thus placing limitations on blood volumes that can be routinely sampled. Accordingly, we developed methods to quantify markers of increasing methaemoglobinaemia at their point of collection that required only 5 μL of whole blood. A 3 μL blood aliquot is pipetted into a plastic micro-cuvette and placed in a custom made holder optically coupled to the Ocean Optics spectrometer, enabling absorbance for oxyhaemoglobin (HbO: 575 nm) and MetHb (630 nm) to be determined. Haemoglobin (HbFe2+), packed cell volume (PCV) and lactate (LAC) data were generated from the remaining 2 μL aliquot apportioned to biosensor strips for the Cera-Check® and Lactate Scout® point-of-care devices. After oral doses of PAPP, a methaemoglobinaemia absorbance index (MAI = absorbance 575 nm-absorbance 630 nm) was strongly and significantly associated with dose-dependent declines in HbFe2+ in 9 bird species. Quantifying dose-dependent responses to MetHb-forming agents at the point of sample collection avoids analytical and storage artifacts arising from sample degradation that appears to be a much greater problem in avian blood compared to mammalian blood.

Pathways to coexistence with dingoes across Australian farming landscapes

IntroductionAgriculture and biodiversity conservation are both vitally important human activities that overlap geographically and are often in conflict. Animal agriculture has been implicated in species loss and the degradation of ecosystems due to land clearing, overgrazing, and conflicts with large carnivores such as dingoes (Canis dingo). This paper explores the potential for transformation in Australian commercial livestock production from human-dingo conflict towards social-ecological coexistence.MethodA qualitative model that depicts transformative change was developed from field observations and twenty-one in-depth interviews with livestock producers, conservation researchers, grazing industry representatives and policy makers across Australia. The model articulates the current state of dingo management and the drivers of system change.ResultsSeven pathways are described to catalyse transformation from routine lethal management of dingoes towards a future vision that embeds mutually beneficial coexistence. Central to transformation is the adoption by livestock producers of preventive non-lethal innovations supported by a new farming movement, Predator Smart Farming, that balances livestock grazing and wildlife conservation values to unlock the resilience of landscapes, animals (domesticated and wild) and livelihoods. Other key pathways include targeted research, capacity building, outreach and knowledge sharing networks; institutional (policy, legislation, and economic incentives) and cultural change; public awareness raising and advocacy to reduce lethal control; and greater involvement of Indigenous Australians in decisions relating to wildlife management.DiscussionThe seven transition pathways are discussed in relation to how they can collectively foster coexistence with dingoes in extensive rangelands grazing systems. International examples of interventions are used to illustrate the types of successful actions associated with each pathway that could inform action in Australia. The findings have implications for coexistence with large carnivores in rangeland ecosystems globally.

The impact of predation by South Island Pied Oystercatchers (Haematopus finschi) on a protected shellfish, the toheroa (Paphies ventricosa), in northern New Zealand

ABSTRACT In northern New Zealand, there is speculation that predation by a recovering shorebird, the South Island Pied Oystercatcher (Haematopus finschi), has caused the continuing decline of an endemic surf clam, the toheroa (Paphies ventricosa). Consequently, there have been requests by the public for these protected birds to be culled to protect and restore the toheroa. To better inform management and decision-making for these species we set out to understand the impact of oystercatcher predation on toheroa at Ripiro Beach in New Zealand. A study was conducted to establish the spatio-temporal overlap of toheroa and oystercatcher distributions, determine oystercatcher prey selection, and assess the impacts of oystercatcher predation on toheroa population size structure. Monthly surveys over a 12-month period indicated limited spatial overlap between the two species, and that most toheroa beds on Ripiro Beach are not subjected to oystercatcher predation. In areas where oystercatchers and toheroa co-occurred, oystercatchers consumed a variety of prey including polychaetes, small and medium-sized toheroa and a non-threatened surf clam (P. subtriangulata). While oystercatchers do feed on toheroa (and may be capable of locally reducing abundance of small toheroa in a population), feeding on larger individuals (>50 mm in length) was not observed. These results suggest that culling of oystercatchers would be of no benefit for the recovery of toheroa populations. It is likely that less obvious factors are impeding the recovery of toheroa in New Zealand. This study highlights the importance of understanding predator-prey interactions before implementing management actions such as lethal control.

Varying response of breeding waders to experimental manipulation of their habitat and predators

Many ground-nesting bird species including waders are of conservation concern across Europe. Population declines of Eurasian Curlew Numenius arquata (hereafter Curlew), a globally Near-threatened wader, exemplify this and are driven by low breeding success due to predation, and loss and degradation of breeding habitat. We tested whether the combined delivery of vegetation management and lethal control of Red Foxes Vulpes vulpes and Carrion Crows Corvus corone and Hooded Crows C. cornix improved Curlew nesting success and breeding abundance across UK study sites over five years. On trial sites, vegetation management improved habitat condition and Curlew distributions shifted towards managed areas. However, changes in predator abundances, Curlew nesting success and Curlew breeding abundance did not differ between trial and reference sites. Northern Lapwing Vanellus vanellus numbers increased on trial sites and decreased on reference sites, whilst Common Snipe Gallinago gallinago numbers showed no treatment response. Some of these outcomes were associated with additional environmental variables added to Treatment:Year terms in three-way interactions (changes in fox abundance associated with abundance of non-native gamebirds; changes in Crow abundance associated with gamebirds and woodland area; changes in Curlew nesting success associated with crow abundance), highlighting that outcomes depend on site-specific contexts, and consistent responses to interventions cannot be assumed. The difficulty in increasing Curlew nesting success likely relates to underlying mesopredator densities in the UK, which are known to be high in a European context. Our results suggest that a model of delivery like this study, including management of predators using lethal control, at comparable intensities, is highly unlikely to be effective for Curlew or Snipe within agri-environment schemes, but could be for Northern Lapwing. To make progress on wader recovery it is imperative to understand the underlying drivers of high mesopredator densities and address these through landscape-scale intervention and policy changes.

Modelling harvest of Greenland barnacle geese and its implications in mitigating human–wildlife conflict

Abstract Arctic‐breeding goose populations have increased in recent decades and their expansion into agricultural areas has caused increasing conflict with farmers due to the damage they cause. Lethal control and scaring are common management strategies of conflict mitigation. Management typically focuses on local/national scales, making addressing the impact of localised control on the wider population challenging, particularly when populations move over large areas and cross international borders. We construct an integrated population model (IPM) to assess the cumulative impact of all shooting harvest (hunting and derogation shooting) on the Greenland barnacle goose, Branta leucopsis. We use data from monitoring schemes throughout the migratory flyway and use population projections to evaluate the impact of potential future shooting strategies on abundance. Our model suggests flyway abundance has declined since its 2012 peak, consistent with an increase in harvest rate and low productivity. Harvest rate increase was most pronounced on Islay (rising from 2% to 7% from 2011 to 2017), suggesting this was a probable cause of flyway abundance decline. Islay abundance has declined since derogation shooting began in 2000, while abundance at other wintering sites has increased. This may indicate that declines in Islay abundance may be due to both shooting mortality and emigration from Islay. Should future flyway‐level harvest rates increase, further declines in abundance could be expected, and are likely to be more pronounced if harvests are extended to the entire winter range. Conversely, should harvest rates decline, an increase in abundance is predicted. Projections can therefore be used to allocate flyway‐level harvest rates to alleviate local pressure without hindering flyway‐level management objectives. Synthesis and applications. Our findings demonstrate the impact of local harvests on global abundance, emphasising the importance of internationally coordinated monitoring and management strategies of migratory species. IPMs provide a framework for adaptation to incorporate additional data when they become available and enable comparisons of future harvest scenarios to inform management strategies throughout the flyway.

Non-Lethal Dose-Response Models Replace Lethal Bioassays for Predicting the Hazard of Para-Aminopropiophenone to Australian Wildlife.

Para-aminopropiophenone (PAPP) is a potent methaemoglobin (MetHb) forming agent used for the lethal control of exotic carnivores and mustelids. To assess the sensitivity of Australian wildlife to PAPP we developed an in vivo assay that did not use death as an endpoint. Sub-lethal dose-response data were modelled to predict PAPP doses required to achieve an endpoint set at 80% MetHb (MetHb80). The comparative sensitivity of non-target mammals referenced to this endpoint was found to be highly variable, with southern brown bandicoots (Isoodon obesulus) the most sensitive species (MetHb80 = 6.3 mg kg-1) and bush rats (Rattus fuscipes) the most tolerant (MetHb80 = 1035 mg kg-1). Published LD50 estimates were highly correlated with PAPP doses modelled to achieve the MetHb80 endpoint (r2 = 0.99, p < 0.001). Most dose-response data for native mammals were collected in the field or in semi-natural enclosures, permitting PAPP and placebo dosed animals to be fitted with tracking transmitters and transponders and released at their point of capture. A protracted morbidity and mortality was observed only in Australian ravens (Corvus coronoides). The combination of sub-lethal dose-response assay and survival data collected in the field provided more relevant information about the actual hazard of pest control agents to non-target wildlife species than laboratory-based lethal-dose bioassays. We discuss the need to replace lethal-dose data with biologically meaningful insights able to define a continuum of toxicological hazards that better serve the needs of conservation and veterinary scientists and wildlife managers.

Public Opinions on Stray Cats in China, Evidence from Social Media Data.

The management of stray cats is often contentious because public perceptions about these animals are different. Using user-generated content from Weibo, this study investigated Chinese citizens' opinions on stray cats on a large scale. Through the techniques of natural language processing, we obtained each Weibo post's topics and sentiment propensity. The results showed that: (1) there were some irresponsible feeding behaviors among citizens; (2) public perceptions of the ecological impacts caused by stray cats were unlike; (3) the trap-neuter-return (TNR) method served high support in public discussion; (4) knowledge about stray cats' ecological impacts was positively correlated with support for the lethal control methods in management. Based on these findings, we suggested that management policies should be dedicated to (1) communicating to the (potential) cat feeders about the negative aspects of irresponsible feeding behaviors; (2) raising "ecological awareness" campaigns for the public as well as highlighting the environmental impacts caused by stray cats; (3) understanding citizens' perceptions toward different management scenarios and making decisions accordingly. In addition, this study also suggested that social media data can provide useful information about people's opinions on wild animals and their management. Policies would benefit by taking this source of information into the decision-making process.

Fertility Control for Wildlife: A European Perspective.

Trends of human population growth and landscape development in Europe show that wildlife impacts are escalating. Lethal methods, traditionally employed to mitigate these impacts, are often ineffective, environmentally hazardous and face increasing public opposition. Fertility control is advocated as a humane tool to mitigate these impacts. This review describes mammalian and avian wildlife contraceptives' effect on reproduction of individuals and populations, delivery methods, potential costs and feasibility of using fertility control in European contexts. These contexts include small, isolated wildlife populations and situations in which lethal control is either illegal or socially unacceptable, such as urban settings, national parks and areas where rewilding occurs. The review highlights knowledge gaps, such as impact of fertility control on recruitment, social and spatial behaviour and on target and non-target species, provides a decision framework to assist decisions about the potential use of wildlife fertility control, and suggests eight reasons for Europe to invest in this area. Although developing and registering contraceptives in Europe will have substantial costs, these are relatively small when compared to wildlife's economic and environmental impact. Developing safe and effective contraceptives will be essential if European countries want to meet public demand for methods to promote human-wildlife coexistence.

Sensitivity of High Conservation Value Birds to Para-Aminopropiophenone (PAPP) Determined by Sub-Lethal Dose-Response Assay.

Para-aminopropiophenone (PAPP) is a methaemoglobin (MetHb) forming compound used for the lethal control of invasive carnivores and mustelids. By measuring the dose-dependent inhibition of O2 transport arising from the oxidation of haemoglobin (HbFe2+) to MetHb (HbFe3+), we determined the sensitivity of nine bird species to PAPP. A methaemoglobinaemia absorbance index (MAI) was validated in five common bird species to determine thresholds associated with a 99% probability of survival (ST99) and a 50% probability of mortality (LT50). Dose-response trials in high conservation value birds sought MAI values below the ST99 threshold, projecting the LT50 value and avoiding the need for lethal outcomes. Black-backed gull (LT50 = 1784.7) and eastern rosella (LT50 = 1074 mg kg-1) were the most tolerant species, while brown kiwi (LT50 = 8.4 mg kg-1) and weka (LT50 = 9.3 mg kg-1) were the most sensitive. Takahē were of intermediate acute sensitivity (LT50 = 51 mg kg-1), although protracted impacts on haemoglobin were observed in takahē up to 72 h later and associated with PAPP doses as low as 25.6 mg kg-1. In pukeko (LT50 = 138.4 mg kg-1), protracted declines in haemoglobin 72 h later occurred at doses as low as 29.5 mg kg-1, while at higher doses (253 and 112 mg kg-1), deaths resulted after 4-6 days. Based upon PAPP doses that caused acute and protracted responses, we provide estimates for the lowest observable adverse effect level (LOAEL) and no observable effects level (NOEL) for nine bird species.

Range Contraction of an Osprey Population Following Lethal Control at a State Fish Hatchery in Montana

Los conflictos entre humanos y Pandion haliaetus aumentan a medida que la especie se recupera de los efectos negativos del DDT. P. haliaetus se alimenta en instalaciones acuícolas en América del Norte, América del Sur y Europa, donde se utilizan controles no letales y letales para reducir las depredaciones. Bajo la autoridad de un permiso federal de control, el personal de una piscifactoría de propiedad estatal en Montana disparó contra ocho individuos de P. haliaetus entre 2018 y 2020 para reducir la pérdida de reproductores de Micropterus salmoides. Los datos independientes a largo plazo (2012–2022) de la ecología reproductiva de P. haliaetus a lo largo del Río Yellowstone, que incluía la piscifactoría, proporcionaron una rara oportunidad para examinar la ocupación del nido y el éxito reproductivo de la población local antes, durante y después del control letal. La población reproductora local de P. haliaetus colapsó en 2021 y el área de reproducción se contrajo de 48 a 67 km durante y después de los disparos. Los disparos en la piscifactoría fueron la mayor fuente de mortalidad de P. haliaetus en el área de estudio lineal de 950 km. En 2021, un grupo de trabajo informal de diversas partes interesadas comenzó a reunirse para desarrollar métodos no letales para reducir las depredaciones de P. haliaetus en la piscifactoría. [Traducción del equipo editorial]

Stable dingo population structure and purity over 11 years of lethal management

Context Interaction between predators and humans is a key driver of human–wildlife conflicts, and can underpin management of predator populations. Management of the impacts of dingoes on livestock and native species is a prime example of a persistent and contentious predator management issue with potential impacts on the integrity of dingo populations. To manage the potential impacts of dingoes and their control, it is imperative to understand the effects of control approaches on their populations in the short and long term. Hybridisation of dingoes with domestic dogs also threatens the genetic integrity of pure dingoes. It has been hypothesised that lethal control of dingoes can facilitate hybridisation through disrupting pack social structures leading to increased dingo–domestic dog interactions. Aims We aimed to to investigate how dingo population structure and genetic purity have changed, assessing dingo purity, individual relatedness, population clustering and gene flow, particularly across land use types and barrier fences, in the context of ongoing lethal control within the Murchison Regional Vermin Cell area in Western Australia (WA). Methods We tested dingo genetic samples from three distinct sampling periods (2009, 2014 and 2020) for changes in population summary statistics and dingo ancestry. Barriers and corridors to gene flow were also examined. Key results We identified three genetically distinct populations in the study area, consistent with previous genetic studies in WA. We did not find any evidence of change in dingo purity or population characteristics; however, barrier fencing may be influencing recent gene flow. Conclusions The metapopulation of dingoes in the southern rangelands of WA appears to be stable over the 11 years assessed. Implications Because we were unable to demonstrate that lethal control has accelerated hybridisation between dingoes and domestic dogs in the study area over the last 11 years, we have no evidence that lethal control to reduce losses to livestock production and for conservation of native wildlife in the southern rangelands of WA is putting dingo purity at risk. Fencing appears to be an effective management tool because there is some evidence it is congruent with reduced gene flow in areas where the fences are well maintained.

Comparing narratives on carnivore management in a dryland ecosystem: a case study of state-backed lethal control

Lethal control of native carnivores as a principal management strategy can have unforseen ecological consequences and is often of questionable efficacy. Using as a case study a region where the lethal control of native puma and culpeo foxes has been incentivised via legislation for over 50 years, we examined how this policy has affected institutional narratives in the region. We conducted four key informant interviews with members of relevant institutions to establish their perspectives on carnivore management. We also examined the informational basis for the current legislative approach to predation, and identified topics for discussion surrounding legislation and its formation for decision-makers in the province. We identified a duality where two branches of gove rnment have contradictory policies regarding livestock production and carnivore management. All institutions involved in predation management in rural landscapes produced narratives supporting sustainable development, and suggested, in varying degrees, that alternatives to lethal control would be positive. Interviewees stated that modification of the existing laws require livestock producers to demand a change from policy-makers, who generally view carnivores poorly. Furthermore, there is evidence that discussions surrounding management strategies suffer from cultural bias, with rural inhabitants finding themselves marginalised from the decision-making process. We identified a need for empathy regarding the adverse situation of rural inhabitants facing the impacts of predation, and an appreciation of the role that carnivores play within their environments, so as to change the negative discourse surrounding human–carnivore interactions.

Immunocontraception of the female African savanna elephant (Loxodonta africana) in South Africa: from pipe dream to policy

Globally, African savanna elephants have been assessed as ‘endangered’. Consequently, additional threats and losses due to human–elephant conflict (HEC) could further exacerbate the species’ decline. In stark contrast, South Africa’s elephant populations are mostly confined within fenced-in reserves that impede natural processes such as migration. As ecosystem engineers, elephant population growth herein should be limited. Within South Africa, elephant management has evolved as differing wildlife philosophies from utilitarian conservation (‘nature for man’) to biocentric preservation (‘nature for nature’) and a combination thereof, have been practiced. Traditionally, both HEC and population control have been largely synonymous with lethal control, i.e. culling. However, with the increase of public or expert input to Policy, lethal control is not favoured by the public. As an alternative, immunocontraception of female African savanna elephants through non-invasive, native porcine zona pellucida (pZP) vaccinations has been employed successfully and is currently adopted in 43 elephant reserves across South Africa. Current legislation now recommends culling as the last population management resort. Newly promulgated legislation calls for wellbeing and welfare to be carefully measured in all biodiversity management decisions taken to minimise threats to biodiversity. As a keystone species, elephant is a direct driver of biodiversity change. Accordingly, and in light of these developments, all population management options, including immunocontraception, must be fully considered in South Africa’s largest national park, the Kruger.

Evaluating predator control using two non-invasive population metrics: a camera trap activity index and density estimation from scat genotyping

Context Invasive mammalian predators are a threat to biodiversity and agriculture globally, yet management outcomes for lethal predator control remain difficult to monitor and evaluate. Understanding whether changes in activity indices correspond to true changes in population density will help inform effective monitoring and management programs. Aims The aim of this study was to evaluate the effect of poison baiting on invasive red fox (Vulpes vulpes) populations using two alternative population metrics: fox activity from camera trap surveys and density estimation from scat genetic analysis. Methods We conducted before–after control–impact studies in two regions of semi-arid Australia (Wimmera and Mallee) by monitoring paired non-treatment and treatment sites during unbaited and baited periods. We estimated the effects of poison baiting on: (1) a monthly fox activity index, derived from an array of 10 off-road camera traps per site; and (2) fox density. To estimate density, we collected fox scats along 14-km transects, identified individuals using polymorphic microsatellite DNA markers and fitted spatially explicit capture–recapture models. Key results Fox activity remained consistently low at all sites except the Mallee non-treatment. The top-ranked models of fox activity and density contained an interaction between treatment and period, with an interactive and additive effect of region, respectively. However, there was little evidence that baiting reduced fox activity or density. In the unbaited period, fox densities ranged from 0.69 (95% CI: 0.47–1.0) to 1.06 (95% CI: 0.74–1.51) foxes km−2 and were similar across regions. Conclusions Camera traps have the potential to provide continuous index-based measures of fox populations but may not record sufficient observations to detect change. Indices can also be confounded by variations in animal behaviour. Scat genetic analysis is a viable option for providing direct estimates of population change at specific snapshots in time; however, this approach is considerably more expensive, and large sample sizes may be required if genotyping success is low. Implications Our study presents a rare example of multiple concurrent – and non-invasive – monitoring techniques to evaluate the effectiveness of predator control. We highlight the value of rigorous study designs and high-quality density information for designing predator management and monitoring programs.

Assessing animal welfare impact of fourteen control and dispatch methods for house mouse (Mus musculus), Norway rat (Rattus norvegicus) and black rat (Rattus rattus).

Population control of the house mouse (Mus musculus), Norway rat (Rattus norvegicus) and black rat (Rattus rattus) is common practice worldwide. Our objective was to assess the impact on animal welfare of lethal and non-lethal control methods, including three dispatch methods. We used the Sharp and Saunders welfare assessment model with eight experts scoring eleven control methods and three dispatch methods used on the three species. We presumed the methods were performed as prescribed, only taking into account the effect on the target animal (and not, for example, on non-target catches). We did not assess population control efficacy of the methods. Methods considered to induce the least suffering to the target animal were captive-bolt traps, electrocution traps and cervical dislocation, while those with the greatest impact were anticoagulants, cholecalciferol and deprivation. Experts indicated considerable uncertainty regarding their evaluation of certain methods, which emphasises the need for further scientific research. In particular, the impact of hydrogen cyanide, chloralose and aluminium phosphide on animal welfare ought to be investigated. The experts also stressed the need to improve Standard Operating Procedures and to incorporate animal welfare assessments in Integrated Pest Management (IPM). The results of our study can help laypeople, professionals, regulatory agencies and legislators making well-informed decisions as to which methods to use when controlling commensal rodents.

Still a good dog! Long-term use and effectiveness of livestock guardian dogs to protect livestock from predators in Australia’s extensive grazing systems

Context Livestock predation is a significant problem for livestock producers all over the world. Livestock guardian dogs (LGDs) can protect livestock from predators, but little is known about the factors that affect their use over long periods of time. Aims Our aims were to investigate the long-term use of LGDs in Australia and determine whether their effectiveness remained high over time, and to establish the reasons for discontinued use. We also wanted to collect data on the fate of LGDs, and how using LGDs affected the use of other methods for predation control. Last, we wanted to estimate the rate at which the use of LGDs is spreading through word-of-mouth. Methods We re-contacted participants from a previous survey of LGD users in Australia and interviewed them about their long-term experience. We were able to include 82% (112) of the original participants, a mean of 8.9 (±0.08) years after the first survey. Key results Half of all original participants were still using LGDs, and in most cases the effectiveness of LGDs had not changed since the first survey. The main reason for ceasing use of LGDs was a change in business that made the dogs unnecessary, followed by unwanted behaviour of dogs, and problems with neighbours. Most LGDs that died prior to old age were euthanised, fell victim to lethal predator control, or were killed by wildlife. Farmers with LGDs reduced other forms of predation control. Informal information transfer among farmers is leading to a net increase in the use of LGDs in Australia. Conclusions LGDs can remain an effective predator control method in Australia with long-term use, and their use is spreading. However, a substantial number of livestock producers experience difficulties in properly training and managing LGDs, leading to failure of the method in some cases and presumably limiting uptake. Implications Given the effectiveness of LGDs for predation management and the many advantages gained by their use, Australia could greatly benefit from programs by government or management agencies both to promote uptake of LGDs and to reduce the incidence of problems by providing farmers with advice and information on best-practice management.

Managing conflict between nesting common terns and herring gulls

Context Due to the frequent depredation of eggs and chicks by herring gulls (Larus argentatus), numerous approaches to reduce their impact on tern colonies have been tested by wildlife managers. Previous studies have shown that the use of overhead lines presents a promising method to prevent gull nesting in tern colonies, but little work has evaluated if this approach is suitable for excluding both nesting and non-nesting gulls. Aims The goal of this study was to explore the efficacy of a preventative approach, overhead lines, versus a more widely practiced lethal approach, shooting and trapping. Specifically, we aimed to determine if methods differ in their abilities to deter both gull nesting and presence within treatment areas and identify impacts on common tern (Sterna hirundo) nesting within treatment areas. Methods We applied separate management strategies to two common tern colonies. In one colony, we removed herring gulls via shooting followed by trapping and nest removal, and in the other colony, we erected overhead lines with subsequent trapping at nests established in the treatment area. Key results Gulls appeared to adapt quickly to shooting efforts, limiting efficacy and resulting in no significant change in abundance from pre-treatment levels (P = 0.981). However, gull use of both the colony and surrounding brush declined significantly (P &lt; 0.001) following trapping and nest removal. Meanwhile, the number of gulls in the colony area declined from a pre-treatment average of 56 to only six, following the erection of overhead lines (P &lt; 0.001). Although six gull nests were established within the treatment area (overhead lines), they were not replaced once the parents were trapped and nests destroyed. Conclusions Tern nesting appeared to be unaffected by any of the implemented management activities. Our data suggest that overhead lines may present an alternative to lethal control when seeking to minimise the impacts of gulls on tern colonies. Implications The data presented in this manuscript can be used to guide managers in selecting actions to reduce conflict between gulls and breeding common terns. By using data-informed practices, managers can select the method best suited for their specific needs and priorities.