No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
Using long-term monitoring of red fox populations to assess changes in rodent control practices
Abstract
Pest control is a global issue for agriculture, health, biodiversity conservation and economy. Anticoagulant rodenticides are used over large areas to control rodent pests and can cause widespread poisoning of nontarget wildlife. In F rance, bromadiolone is the only pesticide authorized to control the water vole A rvicola terrestris S cherman, in grasslands. Since 2001, legislation has been in place to replace curative treatments by preventive ones and limit the quantity of rodenticide used. As the legislation took effect over time, the impact on red fox V ulpes vulpes populations was monitored.
Fox populations and bromadiolone treatments were monitored in the D oubs D epartment (5000 km² area), F rance. Fox counts were carried out during spring, and vole control was primarily conducted in autumn. Relative fox densities ( K ilometric A bundance I ndex: KAI ) obtained per commune for year n (2004–2009) were related to treatments achieved during year n −1 (2003–2008). Treatments from year n −2 were used to investigate possible delayed responses in fox populations.
K ilometric A bundance I ndex of foxes was significantly related to treatment intensities in years n −1 and n −2. The impact was greatest in a large area (>1000 km²), where intensive treatments were achieved in 2003. Fox KAI generally remained dramatically low in this area until 2005, after which a partial recovery was observed.
The same area was treated again from 2006 to 2008 but with only half the amount of bait per hectare that was used in 2003. These treatments were followed by a moderate decrease in fox populations.
Synthesis and applications : We have established, for the first time on a regional scale, the negative impact of a rodenticide on fox populations. We have shown that a shift to preventive treatments with reduced anticoagulant rodenticide use is less harmful to fox populations. However, to approach a zero impact, treatments should be reduced further by limitation of bait quantities authorized per hectare and per commune and using alternative methods to chemical control. Long‐term monitoring of wildlife populations using index methods can provide valuable information about the adverse effects of pesticides; therefore, we recommend their inclusion in the assessment of pest management practices.
... This status places them at the heart of management conflicts where crop protection and health concerns are often raised against conservation issues (Delibes-Mateos et al., 2011). Moreover, poisoning when using chemicals for rodent pest control can depress populations of predators that are able to contribute to the regulation of rodent populations Jacquot et al., 2013). A better understanding of the links between grassland vole population variations and predator responses will allow more timely and better focused management actions for all stakeholders in multifunctional socio-ecosystems. ...
... The variation in this predator community structure over the time span of large fluctuations of prey abundance has not been documented yet in this system, limiting both comparisons with ecosystems described in other part of the world where small mammal outbreaks occur (Jacob et al., 2020) or with more simple food webs of northern ecosystems. Moreover, a large-scale inadvertent experiment was offered by chemical control of vole populations in the 1990s, leading to a dramatic decrease in the fox population due to secondary poisoning, and its gradual recovery the following years after a shift in vole control practices (Jacquot et al., 2013). ...
... In France, bromadiolone, an anticoagulant rodenticide, has been used to control water vole populations since the 1980s, with deleterious effects on nontarget wildlife including vole predators . In the early 2000s, the development of an integrated pest management (IPM) approach led to a dramatic decrease in the quantity of bromadiolone applied by farmers and their nonintentional effects Jacquot et al., 2013). By law, the delivery of bromadiolone baits for vole control to farmers is under strict FREDON supervision and compulsory usage declaration to ensure traceability (Legifrance, 2014). ...
Voles can reach high densities with multiannual population fluctuations of large amplitude, and they are at the base of predator communities in Northern Eurasia and Northern America. This status places them at the heart of management conflicts wherein crop protection and health concerns are often raised against conservation issues. Here, a 20‐year survey describes the effects of large variations in grassland vole populations on the densities and the daily theoretical food intakes (TFI) of vole predators based on roadside counts. Our results show how the predator community responded to prey variations of large amplitude and how it reorganized with the increase in a dominant predator, here the red fox, which likely negatively impacted hare, European wildcat, and domestic cat populations. This population increase did not lead to an increase in the average number of predators present in the study area, suggesting compensations among resident species due to intraguild predation or competition. Large variations in vole predator number could be clearly attributed to the temporary increase in the populations of mobile birds of prey in response to grassland vole outbreaks. Our study provides empirical support for more timely and better focused actions in wildlife management and vole population control, and it supports an evidence‐based and constructive dialogue about management targets and options between all stakeholders of such socio‐ecosystems.
... Despite AR being exclusively licensed for rodent control, a large number of predator species are secondarily exposed to AR (Sánchez- Barbudo, Camarero, & Mateo, 2012). Consumption of dead and sub-lethally intoxicated voles reduced fox abundance in farmland in eastern France (Jacquot et al., 2013) and ARs caused short-term declines in stoats in New Zealand (Alterio, 1996). Rodent-eating mustelid populations are affected by ARs given the pervasive levels of contamination reported (McDonald, Harris, Turnbull, Brown, & Fletcher, 1998). ...
... For the toxicokinetics of AR ingested by voles, a fraction CV was assumed to remain active and available to predators ingesting voles. The absorption rate of ARs (η) exceeds 50% in less than 24 hr (Jacquot et al., 2013). The excretion rate from voles, k out , V was 0.4/day (Sage et al., 2008). ...
... Firstly, low mustelid densities inhibit their regulation of voles and contribute to farmer AR use. In line with empirical evidence, the latter directly impacts foxes by poisoning (Jacquot et al., 2013). Secondly, fox predation on mustelids is reduced, and with an intermediate AR amount, this allows mustelids to slowly recover. ...
Understanding pesticide impacts on populations of target/non‐target species and communities is a challenge to applied ecology. When predators that otherwise regulate pest densities ingest prey contaminated with pesticides, this can suppress predator populations by secondary poisoning. It is, however, unknown how species relationships and protocols of treatments (e.g. anticoagulant rodenticide [AR]) interact to affect pest regulation.
To tackle this issue, we modelled a heuristic non‐spatialized system including montane water voles, specialist vole predators (stoats, weasels) and a generalist predator (red fox) which consumes voles, mustelids and other prey. By carrying out a broad‐range sensitivity analysis on poorly known toxicological parameters, we explored the impact of five farmer functional responses (defined by both AR quantity and threshold vole density above which AR spreading is prohibited) on predator–prey interactions, AR transfer across the trophic chain and population effects.
Spreading AR to maintain low vole densities suppressed mustelid and fox populations, leading to vole population dynamics being entirely regulated by AR use. Such vole‐suppression treatment regimes inhibited predation ecosystem services and promoted pesticide dependence.
Keeping vole density below acceptable bounds by spreading AR while maintaining sufficient voles as prey resources led to less AR being applied and extended periods without AR in the environment, benefiting predators while avoiding episodes with high vole density. This may meet farm production interests while minimizing the impact on mustelid and fox populations and associated ecosystem processes. These alternating phases of mustelids and farmer regulation highlight the consequence of intraguild relationship where mustelids may rescue foxes from poisoning. Both global and wide‐range sensitivity analysis illustrate the tightrope between predator–prey regulation and pesticide–pest regulation.
Synthesis and applications . Different pesticide protocols lead to a rich variety of predator–prey dynamics in agro‐ecosystems. Our model reveals the need to maintain refuges with sufficient non‐poisoned voles for sustaining specialist mustelids, to conserve the predator community given the potential of secondary poisoning with rodenticides. We suggest that long periods without pesticide treatment are essential to maintain predator populations, and that practices of pesticides use that attempt to permanently suppress a pest over a large scale are counterproductive.
... The reduction in concentration of bromadiolone per hectare, and its application at low-intermediate WV densities, clearly diminished the poisoning risk for the red fox and other relatively visible species. 15,16 However, this result does not preclude undetected effects on more discreet species such as small mustelids (SMs), including weasels, Mustela nivalis L., and stoats, Mustela erminea L. [17][18][19][20] SMs show a high frequency of rodent consumption, and SM-rodent dynamics are closely related at the multiannual scale. 21,22 At the yearly scale, SM breeding matches the period of WV population growth, from spring to autumn, as WVs breed during the whole snow-free period. ...
... The abundance declines are consistent with those obtained in SM populations after AR (brodifacoum and pindone) use in New Zealand and with declines in red fox abundance in areas intensely treated with bromadiolone in the Jura Mountains in France. 16,[25][26][27] We estimated SM abundance, but unfortunately we could not identify weasels and stoats separately. 33 In any case, we know that both are at risk of dying after consuming ARs, and it is likely that both are affected in their abundance. ...
... poisoned voles may kill predators or affect their reproduction, which ultimately may reduce predator abundance). 16,61,62 Fortunately, the problem of non-target exposure to bromadiolone used for plant protection is expected to decrease considerably given that in almost all EU Member States no bromadiolone products are authorized for field use. ...
BACKGROUND
The use of pesticides can affect non‐target species by causing population declines through indirect intoxication. Small mustelids (SMs; weasels, Mustela nivalis L.; stoats, Mustela erminea L.) consume water voles (WVs, Arvicola scherman S.) and can be exposed to bromadiolone, an anticoagulant rodenticide used in some countries to reduce WV damage to grasslands. Here, we investigated whether bromadiolone affected SM abundance.
RESULTS
We monitored SM abundance using footprint tracking tunnels in spring and autumn at 10 sites. Among these sites, 4 were treated with bromadiolone, while 6 were not treated. We found reduced SM abundance at these 4 sites from spring to autumn (treated sites, mean±SE SM abundance change=‐1.68±0.42; untreated sites, 0.29±0.25). Using a linear model, we observed that SM abundance decreased as a function of the quantity of bromadiolone applied during the 3 months before the autumn estimate. We found that WV abundance increased at treated sites (linear model, treated sites, mean±SE WV abundance change=1.4±0.4; untreated sites, 0.33±0.25). Thus, at treated sites, SM abundance declined despite increased food availability. By analyzing residues in vole livers and SM scats we showed that SMs may be exposed to bromadiolone at the sites where this compound was used.
CONCLUSION
This study is the first to document the relationship between SM abundance and bromadiolone usage for small mammal control. Declines in SM abundance were observed at treated sites, where bromadiolone residue was found in SM scats. This correlative approach suggests that bromadiolone treatment may lead to seasonal SM declines and associated WV increases.
This article is protected by copyright. All rights reserved.
... Furthermore, use of ARs to protect croplands, grassland and forestry also self-evidently requires open area deployment of rodenticides. When used outdoors, baits can be placed down the burrow entrance of the target species (Khan et al. 1998;Tobin et al. 1997) or specifically inserted into tunnel/gallery systems (Jacquot et al. 2013;Sage et al. 2008). This may to some extent reduce but not eliminate non-target exposure but efficacy of control of target species will in part depend on ability to locate a high proportion of occupied burrows. ...
... Compared with wood mice and bank voles, fewer non-target Microtus voles were exposed when ARs were used as biocides (median: 7%; range 3-19.5%), although common voles were widely exposed (36-41% of individuals contaminated) when ARs were used as plant protection products against the sympatric water vole (Jacquot et al. 2013;Sage et al. 2008). Shrews were also frequently exposed to ARs in the studies we examined. ...
... Some factors are intrinsic components of study design and include the proximity of trapping to baiting areas and the timing of sampling relative to onset of baiting; both tend to vary between individual studies. The extent of exposure in non-target small mammals has been found to decline with distance from baited areas (Geduhn et al. 2014;Jacquot et al. 2013;Townsend et al. 1995) and exposure would likewise be expected to decline following cessation of baiting. Tosh et al. (2012) attributed the relatively low detection of contamination in non-targets on farms in their study partly to the fact that trapping was only conducted 6-8 weeks after onset of baiting campaigns. ...
The toxicity of anticoagulant rodenticides to non-target species is one of the root concerns over wide-scale use of these compounds. Compared with the numerous studies documenting secondary exposure in predators, there have been relatively few studies on primary exposure in non-targets. We consider why primary exposure of non-targets occurs, which species are most likely to be exposed, how and why exposure magnitude varies, and whether exposure results in ecologically significant effects. Species groups or trophic guilds most at risk of primary exposure include invertebrates, reptiles, birds and mammals. Relatively little is known about exposure and particularly effects in invertebrates and reptiles although recent studies suggest that anticoagulants may impact invertebrates, presumably through different toxic pathways to those that result in vertebrate toxicity. Amongst higher vertebrates, primary exposure occurs in some bird species but there is little information on extent and importance. There are more studies on non-target mammals and it is granivorous species that are most likely to feed on bait and accumulate residues, as might be predicted given their ecological and trophic similarities to target species. However, studies suggest a surprisingly high degree of exposure in shrews, although it is unclear the extent to which this is primary and/or secondary. Overall, arguably the most striking aspect of primary exposure in mammals is the large-scale variation both in the proportion of animals exposed and the magnitude of residues accumulated. We consider the multiple abiotic and biotic factors that may drive this, including the direct and indirect effects of resistance in target species. In terms of ecologically significant effects, primary exposure clearly does cause acute mortalities in non-target vertebrates and these have been associated with significant population impacts on intensively baited islands where there has been limited or no potential for immigration. Localised population impacts have also been documented in mainland small mammals but most non-targets are likely to be r-selected species. Population declines may therefore be expected to be relatively short-term, provided baiting is episodic, as population numbers can recover through high intrinsic rate of reproduction in survivors, reduced density-dependent mortality, and immigration. However, prolonged or permanent baiting may potentially result in long-term depletion of resident non-target populations that is ameliorated only by immigration; such areas may act as population sinks.
... Toutefois, quelques études sur des populations sauvages permettent d'aborder cette problématique. Dans le département du Doubs (France), les densités relatives de renard roux ont été corrélées négativement avec l'intensité des traitements à la bromadiolone, un rodenticide anticoagulant appliqué en usage agricole (Jacquot et al., 2013). Le secteur le plus fortement traité présentait des densités proches de 0 renard par km² sur 120 km² et < 0,5 renard par km² sur 1 000 km² l'année suivant les traitements, la prise en compte d'autres causes possibles de déclins suggérant que l'empoisonnement direct des renards expliquait le plus probablement les effets constatés. ...
... Le secteur le plus fortement traité présentait des densités proches de 0 renard par km² sur 120 km² et < 0,5 renard par km² sur 1 000 km² l'année suivant les traitements, la prise en compte d'autres causes possibles de déclins suggérant que l'empoisonnement direct des renards expliquait le plus probablement les effets constatés. Ces auteurs ont également montré que les populations impactées nécessitent au moins 2 ans pour retrouver des densités proches de celles des autres secteurs du département (Jacquot et al., 2013). Dans un écosystème forestier, l'analyse croisée des effets des incendies et des traitements herbicides (pour limiter ces incendies) sur les populations d'écureuils Sciurus niger aux USA a démontré un lien entre l'application d'herbicide (hexazinone) et la diminution des populations. ...
... Correction of power lines and careful placement of wind farms are frequently used approaches for mitigating red kite mortality through collision and electrocution (e.g., in Czech Republic, Germany Portugal, and Spain; Hernandez-Lambrano et al., 2018). Trained dogs to locate poisoned baits and integrated pest management to reduce the use of pesticides have also been deployed in many parts of the range to reduce the risks associated with poisoning (Table 2; Deak et al., 2020;Jacquot et al., 2013;Knott et al., 2009). Such dog units were successfully deployed in Sardinia and in the Italian peninsula through two recent EU LIFE projects (LIFE13 NAT/IT/000311; LIFE14 NAT/IT/000484). ...
... As an illustrative example, using models to predict areas with high risk of primary (Mateo-Tomás et al. 2012, 2020 and secondary (Imholt et al., 2015;Jacob et al., 2014) poisoning could inform spatiotemporally explicit efforts to mitigate negative impacts on red kites and other flesh eaters. Such measures could include incentives for farmers to reduce their use of toxic pesticides (Jacquot et al., 2013), providing safe food alternatives for carnivorous wildlife Orros and Fellowes, 2015), and increased enforcement and outreach to reduce persecution (Christie, 2007). ...
Calls for urgent action to conserve biodiversity under global change are increasing, and conservation of migratory species in this context poses special challenges. In the last two decades the Convention on the Conservation of Migratory Species of Wild Animals (CMS) has provided a framework for several subsidiary instruments including action plans for migratory bird species, but the effectiveness and transferability of these plans remain unclear. Such laws and policies have been credited with positive outcomes for the conservation of migratory species, but the lack of international coordination and on-ground implementation pose major challenges. While research on migratory populations has received growing attention, considerably less emphasis has been given to integrating ecological information throughout the annual cycle for examining strategies to conserve migratory species at multiple scales in the face of global change. We fill this gap through a case study examining the ecological status and conservation of a migratory raptor and facultative scavenger, the red kite (Milvus milvus), whose current breeding range is limited to Europe and is associated with agricultural landscapes and restricted to the temperate zone. Based on our review, conservation actions have been successful at recovering red kite populations within certain regions. Populations however remain depleted along the southern-most edge of the geographic range where many migratory red kites from northern strongholds overwinter. This led us to a forward-looking and integrated strategy that emphasizes international coordination involving researchers and conservation practitioners to enhance the science-policy-action interface. We identify and explore key issues for conserving the red kite under global change, including enhancing conservation actions within and outside protected areas, recovering depleted populations, accounting for climate change, and transboundary coordination in adaptive conservation and management actions. The integrated conservation strategy is sufficiently general such that it can be adapted to inform conservation of other highly mobile species subject to global change.
... For instance, in eastern France, hunters within the "Fédération Départementale des Chasseurs du Doubs" are organized with the help of researchers to collect abundance data from spotlight night counts in a standardized way every year. These data allow identifying wildlife population changes and may trigger specialized investigations (Jacquot et al. 2013). For instance, the anticoagulant bromadiolone was employed as a plant protection product by farmers to combat outbreaks of water voles (Arvicola scherman), with subsequent accumulation and observed population declines in predators (Jacquot et al. 2013;Fernandez-de-Simon et al. 2019 Hunters facilitate samples (blood, organs, ticks) that can be collected by researchers. ...
... These data allow identifying wildlife population changes and may trigger specialized investigations (Jacquot et al. 2013). For instance, the anticoagulant bromadiolone was employed as a plant protection product by farmers to combat outbreaks of water voles (Arvicola scherman), with subsequent accumulation and observed population declines in predators (Jacquot et al. 2013;Fernandez-de-Simon et al. 2019 Hunters facilitate samples (blood, organs, ticks) that can be collected by researchers. Hunters are also in direct contact with nature and may alert of mortality events. ...
Many game species are prey species and evolved to cope with significant mortality by natural predators. In the absence of predation or hunting, these game populations will be limited by resource depletion or disease. Both situations may fall within the overabundance definition. We review drivers of game species overabundance, considering if recreational hunting can effectively manage this challenge. We show examples of overabundance management in European rabbits (Oryctolagus cuniculus), deer (red deer Cervus elaphus and white-tailed deer Odocoileus virginianus), and wild boar (Sus scrofa) or its relative, the feral pig. We also consider available alternatives for managing overabundant wildlife such as habitat management, predator restoration, pathogen introductions, professional culling, immunocontraception, and poisoning. Most alternatives can be included in integrated wildlife management strategies but are unsuitable alone for large-scale overabundance control. We conclude that, when available, it is advisable to use recreational hunting as one tool in the box. Recreational hunting will perform best as a means of population control within integrated wildlife management strategies, combining hunting with habitat management. To maintain the contribution of recreational hunting for managing overabundance, hunters need to survey demographics of game populations to adequately plan harvest quotas. They should continue developing their commitment with biodiversity conservation, monitoring programs, and animal/public health. Agencies could set acceptable targets and facilitate hunting, educating the public about recreational hunting as socio-ecological service. Hunting and conservation should go hand in hand, with special caution regarding native endangered species that locally become pests needing sustainable management including adaptive hunting.
... In any case, it is important considering that any rodent control system potentially may have side-effects on non-target species, and thus the relevant point is evaluating which system has less important undesired side-effects. In this sense, the detected side-effect of biological control of voles, a reduction in the abundance of some alternative bird prey species, looks less important that the reported colateral effects of SGAR use, that may have important impacts on the community of predators, particularly raptors (Langford et al., 2013), but also mammals (Jacquot et al., 2013). This side-effect of SGARs can be considered more relevant because predators are usually scarce species with disperse distribution and low-density populations as compared to Passerines, what is often reflected in their respective conservation status, such as relatively many more species of raptors are usually considered endangered as compared to passerines. ...
... This side-effect of SGARs can be considered more relevant because predators are usually scarce species with disperse distribution and low-density populations as compared to Passerines, what is often reflected in their respective conservation status, such as relatively many more species of raptors are usually considered endangered as compared to passerines. Last, but no least, the main sideeffect of SGARs implies a potential reduction in the abundance of vole predators, even at regional level (see Mougeot et al., 2011 for the case of red kites in NW Spain or Jacquot et al., 2013 for foxes in France). Consequently, the co-lateral effect of this control system may result in a reduction in the potential of natural control of vole numbers by wild predators, what in turn would require more frequent or massive use of SGARs in what could become a vicious circle, perhaps already occurring in areas of NW Spain where biological control seems to be less effective controlling vole abundance than in the study area of this paper. ...
Biological control of rodents in agricultural areas, increasing avian predator abundance by nest-box provisioning, has been proposed during the last decades in several regions around the world as an alternative to the widespread use of anticoagulant rodenticides (AR) to protect crops. However these experiences have often lacked a “Before-After-Control-Impact” (BACI) experimental design providing evidence strong enough about their efficacy reducing vole abundance or crop damages. Furthermore, little is known about possible indirect effects on non-target species.
Here we test the effectiveness of providing nest-boxes to common kestrels (Falco tinnunculus) and barn owls (Tyto alba) in reducing the abundance of two different vole species using indirect index methods to estimate rodent abundance in late spring (May). We monitored the abundance of both vole species in a treatment (with nest boxes) and control (without nest boxes) areas during three years in alfalfa fields, using a BACI design. We studied also the efficiency of this control method in three different crops (alfalfa, cereal and fruit-trees) during the last year of the experiment. We compare the results obtained in this study area in NE Spain with those obtained simultaneously in other three experimental areas in NW Spain. Finally we explored potential negative effects of this method on the abundance of several passerine birds present in our research area.
Our results showed a clear-cut reduction in the abundance of the two vole species, the common vole (Microtus arvalis) and the mediterranean-pine vole (Microtus duodecimcostatus) in the experimental area after applying the treatment (nest box installation) in alfalfa crops. We also found a significant decrease in the presence of both species of voles on fruit-tree plantations and alfalfa crops but we did not find significant effects in the cereal fields, where voles were in general very scarce. These results suggest higher efficacy of biological control in this study area than in some areas of NW Spain, what could be explained by several non-exclusive hypotheses presented in the discussion.
For other species, we found a negative effect of nest-boxes on the abundance of a limited number of common bird species, but also positive effects over other species using poles with nest-boxes as perches.
In conclusion, under the conditions of our study area, nest-box provisioning seemed to be an effective technique to reduce vole abundance, but also had some undesired side-effects on non-target species. However, these side-effects affected mainly to common bird species and can thus be considered less relevant than those caused by SGARs, often affecting to endangered rodent predators and that could thus have negative effects over any potential future natural control of vole abundance, potentially increasing future needs of SGAR use in a vicious circle.
... Bromadiolone is an authorized AR in Europe for plant protection purposes, and in France it may be applied in fields to control rodents, most notably water vole (Arvicola scherman) outbreaks, that may affect harvest of fodder. Field applications of bromadiolone in Franche-Comté and Auvergne regions have been reported as being responsible for exposure and poisoning of foxes (Vulpes vulpes) (Sage et al., 2010;Jacquot et al., 2013Jacquot et al., , 2014, and represents a threat to endangered species such as the red kite (Milvus milvus) that consume water voles during outbreaks (Coeurdassier et al., , 2014a(Coeurdassier et al., , 2014bDecors et al., 2012). A list of mitigation measures was developed in the early 2000s and was proposed to farmers to lower the ecological consequences of bromadiolone treatments. ...
... A list of mitigation measures was developed in the early 2000s and was proposed to farmers to lower the ecological consequences of bromadiolone treatments. In Franche-Comté region, adoption of these measures led to a substantial decrease in non-target wildlife mortality since 2006 (Jacquot et al., 2013). However, secondary exposure has not completely disappeared and new additional approaches are required to reduce adverse effects of ARs on predators and scavengers (Rattner et al., 2014;Coeurdassier et al., 2014b;Elliott et al., 2016;Smith and Shore, 2015). ...
Anticoagulant rodenticides (ARs) are widely used pesticides to control rodent populations. Bromadiolone, a second generation anticoagulant rodenticide (SGARs), is authorized in France to control the population of water voles (Arvicola scherman). The persistence of SGARs in rodents is responsible for secondary exposure or poisoning of predators and scavengers, and is of ecological concern for the conservation of endangered species. Commercial formulations are a mixture of two diastereoisomers of bromadiolone: 70–90% is trans-bromadiolone and 10–30% is cis-bromadiolone. Both diastereoisomers have been shown to inhibit coagulation function with the same potency. On the other hand, cis-bromadiolone has been shown to be less tissue-persistent than trans-bromadiolone in rats. This difference led to residue levels in rats with substantially weakened proportion in cis-bromadiolone compared to the composition of baits.
... Since the first reports of anticoagulant residues in British raptors (Newton et al. 1990), SGARs have become contaminants of avian and mammalian predators and scavengers in jurisdictions worldwide (table 1), including national parks remote from intensive human activities (Gabriel et al. 2012). Many questions still remain, and further research is needed to quantify what proportion of exposed animals are acutely poisoned, the importance of sublethal effects such as increased clotting times, and whether there are any population-level impacts (Thomas et al. 2011, Coeurdassier et al. 2012, Jacquot et al. 2013, Rattner et al. 2014, Hindmarch and Elliott 2015a. The fact remains, however, that there are now relatively few anthropogenic chemicals, other than SGARs, that are widespread contaminants of top predators and are lethal toxicants. ...
... A cautionary note, however: Although there are data on cost savings to corporate and other end users from such IPM-based reductions in usage (Arjo et al. 2009), it is much less clear whether changing from prophylactic to evidencedriven bait deployment has resulted in significant reductions in the availability of poisoned rodents to predators and scavengers. There is some evidence that restrictions on the field use of anticoagulants in France resulted in both decreased amounts of products applied and increased population densities of the red fox (Vulpes vulpes) following periods of reduced rodenticide usage (Jacquot et al. 2013). We are not aware of other studies that quantified the mitigating efficiency on actual risks. ...
Anticoagulant rodenticides, mainly second-generation forms, or SGARs, dominate the global market for rodent control. Introduced
in the 1970s to counter genetic resistance in rodent populations to first-generation compounds such as warfarin, SGARs are
extremely toxic and highly effective killers. However, their tendency to persist and accumulate in the body has led to the
widespread contamination of terrestrial predators and scavengers. Commercial chemicals that are classified by regulators as
persistent, bio-accumulative, and toxic (PBT) chemicals and that are widely used with potential environmental release, such
as dichloro-diphenyl-trichloroethane (DDT) or polychlorinated biphenyls (PCBs), have been removed from commerce. However,
despite consistently failing ecological risk assessments, SGARs remain in use because of the demand for effective rodent-control
options and the lack of safe and humane alternatives. Although new risk-mitigation measures for rodenticides are now in effect
in some countries, the contamination and poisoning of nontarget wildlife are expected to continue. Here, we suggest options
to further attenuate this problem.
... En effet, si les dégâts agricoles liés aux pullulations de micro-mammifères est un processus qui revêt une importance économique au niveau mondial, il revêt parfois d'une importance vitale pour nombre de populations humaines des pays pauvres et émergents (Mwanjabe et al., 2002; Singleton, 2003; Singleton et al., 2005b; Meerburg et al., 2009; Jacob et al., 2010; Monadjem et al., 2011). Zhang et al., 2003; Sage et al., 2008; Berny et al., 2010; Coeurdassier et al., 2012; Gabriel et al., 2012; Jacquot et al., 2013; Coeurdassier et al., 2014; Montaz et al., 2014; López-Perea et al., 2015) (Figure 6). Enfin, la capacité des micro-mammifères à pulluler en font des espèces clés dans le fonctionnement des agro-écosystèmes en tant que réservoir de zoonoses (Boué et al., 2010; Wang et al., 2010; Decors et al., 2011; Said-Ali et al., 2013; Guerra et al., 2014; Mayer-Scholl et al., 2014) (Figure 7) ou comme maillon essentiel des réseaux trophiques, notamment comme ressource alimentaire de la communauté de prédateurs (Hanski et al., 2001; Ekerholm et al., 2004; Korpimäki et al., 2004). ...
... or culling have been used to monitor red fox populations (Jacquot et al., 2013). However, these methods pose several limits (biased density estimation, culling effort dependent. ...
... Pesticides are known to negatively impact non-target species, and SGAR residues have been found in many non-target species [14,15,17,20,49], including the kit fox [41,42]. Our study is one of the first to examine how rodenticides affect an entire wildlife population across its range, and where, in a complex landscape, those effects might be most severe (but [49] also considers spatial impacts across a limited population). ...
... Pesticides are known to negatively impact non-target species, and SGAR residues have been found in many non-target species [14,15,17,20,49], including the kit fox [41,42]. Our study is one of the first to examine how rodenticides affect an entire wildlife population across its range, and where, in a complex landscape, those effects might be most severe (but [49] also considers spatial impacts across a limited population). Our model predicted that 36% of kit foxes were likely exposed to SGARs, resulting in an estimated 7-18% reduction in the population depending on the mortality rate. ...
Although rodenticides are increasingly regulated, they nonetheless cause poisonings in many non-target wildlife species. Second-generation anticoagulant rodenticide use is common in agricultural and residential landscapes. Here, we use an individual-based population model to assess potential population-wide effects of rodenticide exposures on the endangered San Joaquin kit fox (Vulpes macrotis mutica). We estimate likelihood of rodenticide exposure across the species range for each land cover type based on a database of reported pesticide use and literature. Using a spatially-explicit population model, we find that 36% of modeled kit foxes are likely exposed, resulting in a 7-18% decline in the range-wide modeled kit fox population that can be linked to rodenticide use. Exposures of kit foxes in low-density developed areas accounted for 70% of the population-wide exposures to rodenticides. We conclude that exposures of non-target kit foxes could be greatly mitigated by reducing the use of second-generation anticoagulant rodenticides in low-density developed areas near vulnerable populations.
... Recent studies have focused on two aspects. The first is the influence of livestock grazing on zokor density by changing soil and plant properties [16][17][18] . For example, Harris et al. (2015) 19 found that zokor density is positively correlated with grazing intensity because the dominant plants of degraded grassland were preferred by plateau zokors, such as Potentilla anserina, Geranium wilfordii, and Taraxacum mongolicum 20 . ...
Mounds formed by plateau zokors (Eospalax baileyi) in alpine meadows are easily disturbed by livestock. We aimed to reveal the effect of moderate livestock grazing (from October 15 to March 15 of the following year) on plant and soil characteristics of zokor mounds. This study explored the effect of zokor mounds of different ages (2015–2018) on soil nutrient content, soil enzymatic activity, plant diversity, and aboveground biomass (AGB) at grazing and non-grazing sites. Compared with the non-grazing sites, soil organic carbon (SOC), total soil phosphorus, and ratio of SOC to total nitrogen were 16.6%–98.7% higher and soil urease activity was 8.4% and 9.6% higher in 1- and 3-year-old mounds, respectively, at the grazing sites. Grazing significantly increased the plant Pielou index, richness, and Shannon–Wiener diversity index of 4-year-old mounds by 20.7%–52.4%. Partial least squares path modeling showed that plant species diversity was the main factor affecting the plant AGB of mounds at the grazing sites, whereas soil enzyme activity was the primary factor at the non-grazing sites. We propose that moderate grazing increases soil nutrient content and the plant diversity in zokor mounds in alpine meadows, which should be considered in future grassland restoration.
... AR were found in 93% of all harrier carcasses (n = 58), and in 62% of these the concentration was compatible with a decline in physiological functions and demographic rates. Exposure of non-target wildlife to ARs is a widespread conservation concern and has been associated with declines in predator populations (Jacquot et al. 2013, Fernandez-de-Simon et al. 2019, Roos et al. 2021. Acute exposure of predators to ARs has a toxic effect, potentially leading to death (Coeurdassier et al. 2014, Niedringhaus et al. 2021. ...
Gathering demographic information on rare species is critical to understanding their population dynamics and implementing efficient conservation measures. Using integrated models, we jointly analyzed multiple data sets, including capture-recapture, GPS tracking and nest monitoring data collected over the last 10 years, to provide the first demographic insights for one of the world's rarest raptors, the endemic Reunion harrier Circus maillardi. We estimated key demographic rates including annual survival and breeding parameters (clutch size, hatching and fledging success), and used population projection models to assess population growth rate and quasi-extinction risk. In order to guide future conservation actions for the population, we evaluated the effects of different management scenarios that improve survival, fecundity, or both, on population growth and quasi-extinction risk. Comparison of the estimated annual survival (juvenile and subadult survival: 0.66; adult survival: 0.71) and breeding parameters (clutch size: 2.3; hatching success: 0.45; fledging success: 0.83) with those of other harrier species suggests that adult survival and breeding parameters of Reunion harri-ers are low. A small data set collected 40 years ago suggests that the probability of an egg producing a fledgling was higher and has declined to the current low level. The population models project that the Reunion harrier population is declining and faces a high risk of quasi-extinction in the next 40 years. Only management measures that simultaneously improve adult survival and fecundity could lead to a recovery of the population. These alarming results call for immediate conservation action aimed at rapidly improving the demographic rates.
... The occurrence of ARs we detected in red foxes in Norway, indicates a risk for wildlife after human AR use (Paper II). A previous study detected a significant reduction in fox populations after bromadiolone treatment, lasting more than one year (Jacquot et al., 2013a). Subtoxic AR concentrations have previously been associated with increased mortality in different species when subjected to stress or exercise (Jaques, 1962;Carvallo et al., 2015). ...
This study was initiated to determine the occurrence of ARs in red foxes in Norway by reversed phase ultra-high performance liquid chromatography–tandem mass spectrometry (UPLC-MS/MS) analyses of faeces. Faecal samples from 163 presumed healthy wild red foxes from most counties in Norway were collected and analysed for six different ARs, and residues were detected in 54% of the animals. Brodifacoum was most frequently detected, followed by coumatetralyl, bromadiolone, difenacoum, difethialone and flocoumafen. More than one substance was detected in 40% of the positive foxes with several exposed to up to four different ARs. There were no statistically significant seasonal, age or sex differences in foxes exposed to ARs. These results indicate a high unintended exposure from ARs in healthy wild foxes throughout Norway.
This study also compared AR levels between faeces and liver from 40 of the same wild red foxes to determine the value of assessing AR exposure by faecal analysis. Residues of ARs were detected in 53% of the faecal samples and 83% of the liver samples. We found good concordance between AR residues in faeces and liver for coumatetralyl, difenacoum, and difethialone. Bromadiolone occurred in significantly greater frequency in livers compared to faecal samples, but no significant difference in concentration
between faeces and liver could be detected. However, brodifacoum displayed a significant difference in concentration and occurrence of positive samples between liver and faeces.
The AR concentrations were analysed in accidentally exposed dogs, displaying biphasic elimination of ARs in faeces. Long terminal half-lives in faeces of 81, 190, 200-330 days were detected for coumatetralyl, difenacoum and brodifacoum, respectively. Comparatively shorter terminal half-life of 30 days was detected for bromadiolone. One of the poisoned dogs
gave birth to four healthy puppies several months after exposure, and low concentrations of brodifacoum were detectable in the puppies’ faeces for at least one month after parturition.
When analysing blood and faeces from 110 healthy domestic dogs, we detected low prevalence of ARs in the healthy dog population. This suggests low exposure of ARs in healthy dogs in Norway.
... It is unclear whether changing from the traditional continuous "preventative" baiting strategies (permanent placement of bait stations with rodenticide bait, checked and refilled at intervals ranging from once a week to once every 3 months) to evidence-driven rodenticide applications will have any impact on the rate of nontarget species exposures (Elliott et al. 2016). Others have shown that the way anticoagulant rodenticides are used can reduce the risks of secondary poisoning of nontargets (Shore et al. 2006, Jacquot et al. 2013, albeit outside of urban areas. ...
... En outre, des intoxications d'oiseaux ont été documentées dans plusieurs pays (Geduhn et al., 2015). En France et au Canada, l'intoxication des renards a causé une baisse de leur densité (Jacquot et al., 2013;Proulx and MacKenzie, 2012). En 2015 , une équipe Allemande montre que sur 331 foies de renards, 59,8% présentaient des résidus d'AVK majoritairement de seconde génération (Geduhn et al., 2015). ...
Les pullulations de campagnols terrestres sont à l’origine de nombreux problèmes. Leur gestion implique différentes mesures mais surtout une lutte chimique par les antivitamines K (AVK). Ces molécules ciblent l’enzyme VKOR codée par le gène VKORC1. L’inhibition de cette enzyme provoque des hémorragies mortelles. L’utilisation intensive des AVK a mené à l’émergence d’une résistance de cible ainsi que des ecotoxicités documentées par plusieurs études. Au cours de ce travail, nous avons étudié la pharmacocinétique de la chlorophacinone et de la bromadiolone chez le campagnol. Nous tenons à préciser que le mélange actuel de bromadiolone utilisé dans la lutte est composé de 85% de l’isomères trans et de 15% de l’isomères cis. Notre étude nous a permis d’identifier une longue demi-vie de l’isomère trans de la bromadiolone contre une demi-vie beaucoup plus réduite pour la cis-bromadiolone et la chlorophacinone. Par conséquence, l’isomère trans est responsable de la persistance de la molécule chez le campagnol et ensuite de l’intoxication des espèces non cible. Nous nous sommes ensuite intéressés au phénomène de la résistance de cible aux AVK.Nous avons tout d’abord, participé à une étude de la résistance sur différents rongeurs piégés en Martinique. Cette étude a permis de mettre en évidence plusieurs mutations dans le gène vkorc1 des rats et des souris. Parmi les souris séquencées, 5 mutations ont été trouvées seules ou en combinaison. Toutes ces mutations étaient des mutations faux-sens A26T, A48T, R61L, Y139C et S149N. La résistance de cible des souris domestiques aux AVK de première génération et même aux AVK de deuxième génération a été clairement démontrée en Martinique surtout avec la détection de la mutation Y139C à une fréquence allélique de 40% et de la double mutation A26T / Y139C à une fréquence allélique de 0,9%. Chez le rat noir, le rongeur le plus répandu en Martinique, 3 nouvelles mutations codantes ont été détectées, les mutations H68N, A115T et S149N associées à une résistance modérée aux AVK de première génération. Parmi les Rattus norvegicus séquencés, une seule mutation silencieuse H68H a été détectée avec une fréquence allélique de 93,3%. Dans un second temps, dans le cadre d’une étude sur le campagnol, nous avons détecté 2 mutations faux-sens (G71R et S149I mutation) avec une très faible prévalence aux seins des populations. Nous avons caractérisé les conséquences catalytiques de ces deux mutations trouvées. Les mutations semblent n’avoir aucun effet sur la résistance aux AVK. Ensuite, nous nous sommes intéressés à la vitamine K chez les campagnols. Le régime alimentaire de ces herbivores est très riche en vitamine K (l’antidote naturel des troubles de coagulation liés à l’utilisation des AVK) et pourrait être responsable de la résistance des campagnols. Ainsi, les campagnols ont montré des concentrations en vitamine K beaucoup plus grandes que celles trouvées chez le rat. En outre, les concentrations de vitamine K chez les campagnols varient avec les saisons, elles sont plus abondantes en été qu’en hiver. Cette variation est liée à la disponibilité de la nourriture qui dépend à son tour des saisons. Il s’agit donc d’une résistance alimentaire. Enfin, nous avons étudié un troisième problème lié aux pullulations des campagnols en évaluant la capacité des campagnols terrestres à participer à la transmission et au maintien du cycle du pathogène dans l’environnement. Ainsi, nous avons cherché à identifier le portage des leptospires par les campagnols dans deux régions de la France touchées par les pullulations (l’Auvergne et la Franche comté). Nous avons identifié la présence, avec une faible prévalence, de L. borgpetersenii et L. kirschneri dans le Cantal et L. borgpetersenii, L. interrogans et L. kirschneri dans le Puy De Dôme. Alors que seule L. kirschneri a été trouvée en Franche comté avec une prévalence beaucoup plus alarmante qu’en Auvergne.
... Most of the literature building on it is methodological, and the applied papers are scarce. In a review of the first 130 Google Scholar citation hits (in order of relevance) for the Kapoor et al. (2007) paper, only a handful actually apply the KKP estimator (GM or ML) empirically: Chakir et al. (2013), Fingleton et al. (2015), Baylis et al. (2012), Wheeler et al. (2013), Romão et al. (2017), Wan et al. (2015), Gomez et al. (2013), Kopczewska et al. (2017), Padovano and Petrarca (2014) and Jacquot et al. (2013). 5 All this despite the fact that a user-friendly R implementation of the KKP-GM estimator has been available since before 2010 as function spgm in the 'splm' package for R (Millo and Piras 2012), together with a more recent KKP-ML equivalent (see function spreml, Millo 2014). ...
We describe a user-friendly, production quality R implementation of the maximum likelihood estimator of the generalized spatial random effects (GSRE) model of Baltagi, Egger and Pfaffermayr within the well known ’splm’ package for spatial panel econometrics. We extend the maximum likelihood estimator for the GSRE to including a spatial lag of the dependent variable (SAR), and we discuss the theoretical and computational approach. This is the first implementation of the SAR+GSRE, and the second of the original GSRE. Until recently only estimators restricting the spatial structure of individual effects in an arbitrary way have been available and widely employed in applied practice. We present results from the SAR+GSRE and the restricted estimators side by side, drawing on some well-known examples from the spatial econometrics literature. The potential biases from imposing inappropriate restrictions to the spatial error process and/or from omitting the SAR term are illustrated by simulation.
... However, the highest liver concentration was measured in 2017, with a bromadiolone hepatic residue of 0.297 mg/kg even though the use of bromadiolone was more restricted. Regulation of bromadiolone applications may reduce the occurrence of bromadiolone in weasels, as in other wildlife (see in Franche-Comté, France;Couval et al., 2013), but vigilance must J o u r n a l P r e -p r o o f continue as acute cases may still happen, even when bromadiolone is used only exceptionally as in2016-2017. ...
Bromadiolone is an anticoagulant rodenticide (AR) commonly used as a plant protection product (PPP) against rodent pests in agricultural lands. ARs can be transferred trophically to predators/scavengers when they consume intoxicated live or dead rodents. ARs exposure in weasels Mustela nivalis, small mustelids specialized on rodent predation, is poorly known in southern Europe. Moreover, in this species there is no information on bioaccumulation of AR diastereomers e.g., cis- and trans-bromadiolone. Trans-bromadiolone is more persistent in the rodent liver and thus, is expected to have a greater probability of trophic transfer to predators. Here, we report on bromadiolone occurrence, total concentrations and diastereomers proportions (trans- and cis-bromadiolone) in weasels from Castilla y León (north-western Spain) collected in 2010–2017, where bromadiolone was irregularly applied to control outbreaks of common voles Microtus arvalis mainly with cereal grain bait distributed by the regional government. We also tested variables possibly associated with bromadiolone occurrence and concentration, such as individual features (e.g., sex), spatio-temporal variables (e.g., year), and exposure risk (e.g., vole outbreaks). Overall bromadiolone occurrence in weasels was 22% (n = 32, arithmetic mean of concentration of bromadiolone positives = 0.072 mg/kg). An individual showed signs of bromadiolone intoxication (i.e., evidence of macroscopic hemorrhages or hyperaemia and hepatic bromadiolone concentration > 0.1 mg/kg). All the exposed weasels (n = 7) showed only trans-bromadiolone diastereomer in liver, whilst a single analyzed bait from those applied in Castilla y León contained trans- and cis-bromadiolone at 65/35%. Bromadiolone occurrence and concentration in weasels varied yearly. Occurrence was higher in 2012 (100% of weasels), when bromadiolone was widely distributed, compared to 2016–2017 (2016: 20%; 2017: 8.33%) when bromadiolone was exceptionally permitted. The highest concentrations happened in 2014 and 2017, both years with vole outbreaks. Our findings indicate that specialist rodent predators could be exposed to bromadiolone in areas and periods with bromadiolone treatments against vole outbreaks.
... Detrimental non-target exposure to ARs has been shown in numerous populations of predators in Europe and North America (Christensen et al., 2012;López-Perea et al., 2015;Riley et al., 2007;Shore et al., 2003;Thomas et al., 2017). These effects can be significant, with populationlevel effects from non-target exposure documented for mammals (Jacquot et al., 2013) and raptors (Thomas et al., 2011). It is thought that species that regularly prey upon small rodents are at higher risk of poisoning, due to the likelihood of consuming AR targeted species (Hindmarch and Elliott, 2018). ...
Anticoagulant rodenticides (ARs) used to control mammalian pest populations cause secondary exposure of predatory species throughout much of the world. It is important to understand the drivers of non-target AR exposure patterns as context for assessing long-term effects and developing effective mitigation for these toxicants. In Australia, however, little is known about exposure and effects of ARs on predators. We detected AR residues in 74% of 50 opportunistically collected carcasses of the Tasmanian wedge-tailed eagle (Aquila audax fleayi), an endangered apex predator. In 22% of birds tested, or 31% of those exposed, liver concentrations of second generation ARs (SGARs) were > 0.1 mg/kg ww. Eagles were exposed to flocoumafen, a toxicant only available from agricultural suppliers, at an exceptionally high rate (40% of birds tested). Liver SGAR concentrations were positively associated with the proportion of agricultural habitat and human population density in the area around where each eagle died. The high exposure rate, in a species not known to regularly prey upon synanthropic rodents, supports the hypothesis that apex predators are vulnerable to SGARs. Our results indicate that AR exposure constitutes a previously unrecognized threat to Tasmanian wedge-tailed eagles and highlight the importance of efforts to address non-target AR exposure in Australia.
... Tableau 11. Caractéristiques de molécules AVKs chez le rat (141) Une étude réalisée dans le département du Doubs a analysé des populations de renards et des quantités de bromadiolone utilisées en lutte chimique pour gérer des populations de Campagnols terrestres (142). Cette étude a montré que l'utilisation de la bromadiolone comme rodenticide avait un impact négatif sur les populations de renards. ...
La gestion de populations de rongeurs est importante car ils peuvent causer divers problèmes économiques, écologiques et sanitaires. Cette gestion s'appuie sur des méthodes de prévention, celles-ci étant des mesures architecturales, hygiéniques et des pratiques agricoles. Elle s'appuie également sur des méthodes de lutte biologique, chimique et mécanique. La lutte chimique se fait principalement avec l'utilisation de rodenticides anticoagulants qui agissent plusieurs heures après ingestion permettant d'éviter l'éviction alimentaire. L'utilisation excessive de ces molécules a entrainé la sélection de résistance chez certains individus rendant leur utilisation peu efficace. Il y a alors eu le développement de nouvelles molécules, mais celles-ci sont plus écotoxiques. Nous nous sommes intéressés dans ces travaux de thèse à la gestion de populations de rongeurs dans un cadre de risque sanitaire leptospirosique. Les rongeurs sont les principaux réservoirs de leptospires pathogènes, des bactéries Spirochètes responsables de la leptospirose. La leptospirose est une zoonose ré-émergeante à répartition mondiale dont le nombre de cas annuel est évalué à approximativement un million et dont il y a eu une augmentation du nombre de cas ces dernières années. Elle est endémique en régions tropicales. C'est une maladie dont l'incidence réelle est sous-estimée en raison notamment de la grande variabilité de symptômes possibles allant du syndrome grippal à des formes rénales. Le taux de mortalité est élevé aux alentours de 10% mais pouvant aller jusqu'à 50% dans certains cas avec des complications pulmonaires. De nombreux facteurs influent sur le cycle complexe de transmission de la leptospirose. Il peut y avoir un risque sanitaire lié à la présence de rongeurs porteurs de leptospires pathogènes, qui peut être difficile à contrôler si les rongeurs sont résistants aux rodenticides anticoagulants utilisés pour réguler leurs populations. De plus, il peut y avoir des problèmes d'exposition à des risques écotoxiques lors de mise en place de traitements chimiques. Nous avons étudié plusieurs cas concrets montrant la difficulté dans la prise de décision liée à la gestion des rongeurs dans des contextes divers. Dans un contexte de problèmes économiques, nous avons analysé le portage de leptospires pathogènes par des campagnols des champs et des campagnols terrestres ainsi que la résistance de cible à la bromadiolone, molécule utilisée en lutte chimique à basse densité de population. Nous nous sommes intéressés à l'influence de la perception sociétale sur le risque sanitaire lié à des souris dans un élevage bovin dans lequel il y a des cas de leptospirose humaine et de leptospirose bovine. Dans le cadre d'un projet visant à étudier l'efficacité de gestion de populations de rongeurs commensaux en Martinique dans un contexte leptospirosique, nous avons regardé l'exposition des rongeurs aux AVKs et la résistance de cible aux AVKs. Pour le portage de leptospires pathogènes par les campagnols nous avons trouvé des prévalences allant de 3% à 53% selon la zone étudiée. Il y avait 3 mutations sur le gène vkorc1 amenant peu de résistance de cible à la bromadiolone. Dans l'élevage bovin nous avons notamment trouvé que la perception sociétale de l'éleveur sous-estimait le risque lié aux souris dont 41% étaient porteuses de leptospires pathogènes et 50% étaient porteuses de mutations du gène vkorc1 amenant de la résistance de cible aux AVKs. En Martinique nous avons trouvé que 54% des individus analysés avaient été exposé à au moins une molécule AVKs et qu'il y avait plusieurs mutations du gène vkorc1 dont certaines pas encore caractérisées amenant de la résistance de cible aux AVKs. La gestion des rongeurs est un problème complexe avec plusieurs facteurs à prendre en compte que ce soient les risques liés à l'exposition aux rongeurs ou ceux liés à l'utilisation de rodenticides anticoagulants [etc...]
... There is a large body of scientific evidence that AR residues occur in mammalian predators and scavengers (Elmeros et al., 2011;Geduhn et al., 2015;Serieys et al., 2019), small mammals (Elliott et al., 2014;Elmeros et al., 2019;Geduhn et al., 2014;Tosh et al., 2012), birds of prey (Thomas et al., 2011), non-raptor birds (Vyas, 2017), owls (Nakayama et al., 2018), reptiles (Lettoof et al., 2020;Rueda et al., 2016), fish (Regnery et al., 2019), invertebrates (Masuda et al., 2015) (Alomar et al., 2018) and sediment . In some species, population effects have been reported at least on local scale such as in red fox (Vulpes vulpes) (Jacquot et al., 2013) and American badger (Taxidea taxus) (Proulx and MacKenzie, 2012). ...
The exposure of non-target wildlife to anticoagulant compounds used for rodent control is a well-known phenomenon. Exposure can be primary when non-target species consume bait or secondary via uptake of poisoned animals by mammalian and avian predators. However, nothing is known about the exposure patterns in passerine birds that are commonly present on farms where rodent control is conducted.
We used liquid chromatography coupled with tandem mass spectrometry to screen for residues of anticoagulant rodenticides (ARs) in liver tissue of passerine birds that were present during rodent control with a product containing brodifacoum (BR). The 222 birds of 13 species were bycatch of rodent snap trapping in 2011-2013 on 11 livestock farms run synchronously with baiting.
During baiting, ARs were detected in about 30% of birds; 28% carried BR. In liver tissue of 54 birds that carried BR, concentrations ranged from 4-7,809 ng/g (mean 490 ±169 ng/g). Among common bird species with AR residues, BR was most prevalent in robins (Erithacus rubecula) (44%) and dunnocks (Prunella modularis) (41%). Mean BR concentration was highest in great tits (Parus major) (902 ±405 ng/g). The occurrence and concentrations of BR residues were about 30% higher in birds collected close to bait stations compared to birds collected further away.
The results demonstrate that several ground feeding songbird species are exposed to ARs used on farms. If BR was present in liver tissue, concentrations were variable, which may imply a combination of primary and secondary exposure of songbirds. Exposure was mostly restricted to the immediate surroundings of farms where bait was used, which might limit the transfer to the wider environment. Efforts should be made to reduce the access for birds to AR bait to prevent high exposure.
... Modelling exercises suggest that the transfer of ARs to mammalian predators is mainly driven by use patterns. 32 For some nontarget species adverse population effects have been suggested such as in non-target rodents, 33 American badger (Taxidea taxus L.), 34 red fox (Vulpes vulpes L.) 35 and mustelids. 36 The ecotoxicological risk associated with widespread application of ARs in crop protection has increasingly lead to restrictions imposed by registration authorities, for instance at the European Union (EU) and at the national level. ...
BACKGROUND
Commensal rodents such as Norway rats (Rattus norvegicus Berk.), black rats (R. rattus L.) and house mice (Mus musculus L.) damage stored produce and infrastructure, cause hygienic problems and transmit zoonotic pathogens to humans. The management of commensal rodents relies mainly on the use of anticoagulant rodenticides (ARs). ARs are persistent and bio‐accumulative, which can cause exposure of non‐target species. We compared the baiting strategies to use brodifacoum (BR) in bait boxes indoors only versus in and around buildings in replicated field trials at livestock farms to assess resulting BR residues in non‐target small mammals.
RESULTS
When bait was used indoors only, the percentage of trapped non‐target small mammals with BR residues as well as BR concentration in liver tissue was about 50% lower in comparison to bait application in and around buildings. These effects occurred in murid rodents and shrews but not in voles that were generally only mildly exposed. During the baiting period, BR concentration in murids was stable but decreased by about 50% in shrews.
CONCLUSION
Restricting the application of BR bait to indoors only can reduce exposure of non‐target species. The positive effect of this baiting strategy on non‐target species needs to be balanced with the need for an effective pest rodent management within a reasonable time. More research is needed to clarify which management approaches strike this balance best.
This article is protected by copyright. All rights reserved.
... Sub-lethal adverse effects mediated by ARs may occur not only at the individual level. Several studies reveal adverse effects on the breeding success of predators and population dynamics (Naim et al., 2011;Proulx and MacKenzie, 2012;Jacquot et al., 2013;Coeurdassier et al., 2014) and the maternal transfer of ARs to progeny (Fisher, 2009;Gabriel et al., 2012). ...
We studied the prevalence of anticoagulant rodenticides (ARs) in liver and muscle tissues of wild boar captured in the urban area of Barcelona, the suburban area of Collserola Natural Park and the rural area of Santa Quiteria, next to Cabañeros National Park, in Spain. The objective is to assess the influence of both urbanisation and wild boar (Sus scrofa) trophic opportunism on the accumulation of these compounds. We have also evaluated the risk for human consumers of this game meat. Wild boars from Barcelona city showed the highest prevalence of ARs detection (60.8%), followed by the adjoining suburban area of Collserola N.P. (40%) and the rural distant area of Santa Quiteria (7.7%). Liver bioaccumulated ARs (45.2%) more frequently than muscle (11.9%). A significant proportion (13.7%), of wild boar captured in Barcelona city exceeded 200 ng/g of total ARs in liver, a threshold for adverse effects on blood clotting. For difenacoum, there was a predominance of cis isomer, while for brodifacoum and bromadiolone cis and trans isomers appeared in a similar proportion. According to the scarce available information on ARs toxicity in humans, the risk of acute poisoning from game meat consumption seems to be low. However, repeated exposure through liver consumption should be considered in further risk assessments because of the high concentration detected in some samples (up to 0.68 mg/kg).
... Grazing livestock have an impact on Tibetan population densities of small mammals through causing changes in the physical and chemical properties of the soil (Pech et al. 2007, Jacquot et al. 2013. These changes, together with a change in availability of foliage, influence population dynamics of small mammals (Jones and Longland 1999, Steen et al. 2005, Zhu et al. 2012. ...
2020. Pika burrow and zokor mound density and their relationship with grazing management and sheep production in alpine meadow. Ecosphere 11(5): Abstract. Plateau pikas (Ochotona curzoniae) and plateau zokors (Myospalax baileyi) occur naturally in the alpine meadow of the Qinghai-Tibet Plateau (QTP). Their feeding and burrowing activities affect plant composition and soil properties (e.g., soil carbon accumulation and soil nitrogen cycling), but research to study the complex interactions between small mammals, livestock, and habitat is currently lacking. We conducted a sheep grazing trial to determine the effect of grazing management on pika burrow and zokor mound density, and the relationships between sheep production and pika burrow and zokor mound density. The grazing management approaches were warm-season rotational grazing at 24 and 48 sheep months (SM)/ha, cold-season rotational grazing at 24 and 48 SM/ha, seasonal continuous grazing at 24 SM/ha, and whole-year continuous grazing at 48 SM/ha. The results of this study suggested that warm-season rota-tional grazing at low stocking rate did not significantly change both pika and zokor densities. Cold-season rotational grazing at both high and low stocking rates and seasonal continuous grazing at low stocking rate led to an increase in zokor mound density, but not pika burrow density. Whole-year continuous grazing at high stocking rate increased both pika and zokor densities. The influence of pika and zokor activities on sheep production was complex and differed between grazing management. Sheep liveweight gain peaked at moderate pika burrow and zokor mound density at low stocking rate under both warm-and cold-season rotational grazing. The threshold values of pika density were about 110 and 70 burrows per hectare in warm and cold seasons, respectively. The threshold value of zokor density was about 400 mounds per hectare in the cold season. In contrast, under high stocking rate regardless of management approach, sheep liveweight gain declined significantly as both pika burrow and zokor mound density increased. This paper provides a theoretical understanding and experimental evidence for sustainable grazing management and restoration of degraded grassland by local herders and policymakers.
... It is unclear whether changing from the traditional continuous "preventative" baiting strategies (permanent placement of bait stations with rodenticide bait, checked and refilled at intervals ranging from once a week to once every 3 months) to evidence-driven rodenticide applications will have any impact on the rate of nontarget species exposures (Elliott et al. 2016). Others have shown that the way anticoagulant rodenticides are used can reduce the risks of secondary poisoning of nontargets (Shore et al. 2006, Jacquot et al. 2013, albeit outside of urban areas. ...
Rodenticides are an essential tool in the integrated pest management of infestations of commensal rodents (Rattus norvegicus, R. rattus, and Mus musculus). With the introduction of Assembly Bill 1788, the California Ecosystems Protection Act of 2019, California is potentially facing a future with new restrictions on the use of anticoagulant rodenticides to manage commensal rodents in urban areas. Assembly Bill 1788 has been proposed specifically to protect predators from anticoagulant rodenticide poisoning and seeks to restrict the application of second-generation anticoagulant rodenticides (SGARs) for use in many urban and non-urban areas of California, USA. Exclusion and cultural practices, such as landscape management and sanitation (i.e., cleaning of property including but not limited to trash containment and removal, and drain sanitation), remain important and successful tools for managing rodent populations. However, increased exposure of wildlife to anticoagulant rodenticides has been detected California. Several animal species have been documented as having succumbed to rodenticide toxicosis. When rodents are killed by SGARs and consumed by predators, SGAR residues have been detected in the livers of predatory species. However, the effects of chronic, sublethal exposure to predators are not well understood. We discuss the current and proposed changes to rodenticide legislation in California, impacts of rodenticide to wildlife, and the potential effects of restrictions on wildlife. We discuss limitations to rodent management programs that have historically replied on the use of SGARs and the potential impacts of the proposed legislation on communities across California. We also identify research gaps that are impeding the adoption of evidence-based best management strategies for rodent control. To improve the success of commensal rodent control programs in California, more research is needed to develop effective strategies for rodent management.
... Although rodenticides are almost indispensable in current agricultural production and urban developments, they have also been shown to harm or kill non-target wildlife through direct consumption of baits (primary exposure, Vyas, 2017;Shore and Coeurdassier, 2018) or preying or scavenging on exposed animals (secondary exposure, Rattner et al., 2014;López-Perea and Mateo, 2018). Many top avian predators have experienced widespread exposure in Europe and North America (Thomas et al., 2011;Jacquot et al., 2013;Rattner et al., 2014;Elliott et al., 2016). ...
Anticoagulant rodenticides (ARs) are known to cause extensive secondary exposure in top predators in Europe and North America, but there remains a paucity of data in Asia. In this study, we collected 221 liver samples from 21 raptor species in Taiwan between 2010 and 2018. Most birds were recovered from rescue organizations, but some free-ranging individuals were obtained from bird-strike prevention measures at airports. ARs were detected in 10 species and more than half of the total samples. Common rodent-eating Black-winged Kites (Elanus caeruleus) had the highest prevalence (89.2%) and highest average sum concentration (0.211 ± 0.219 mg/kg), which was similar between free-ranging birds at airports and injured birds from rescue organizations. Scavenging Black Kites (Milvus migrans) and snake-eating Crested Serpent-eagles (Spilornis cheela) had the second highest prevalence or sum concentration, respectively. Seven different AR compounds were detected, of which brodifacoum was the most common and had the highest average concentration, followed by flocoumafen and bromadiolone. The frequency of occurrence in the three most numerous species (Black-winged Kite, Crested Goshawk [Accipiter trivirgatus], and Collared Scops-owl [Otus lettia]) was significantly higher in autumn than summer, which is consistent with the timing of the Taiwanese government's supply of free ARs to farmers. Regional differences in the detection of individual compounds also tended to reflect differences in human population density and use patterns (in agriculture or urban-dominated environments). Clinical poisoning was confirmed in Black Kites with sum concentrations as low as 0.026 mg/kg; however, further study of interspecific differences in AR sensitivity and potential population effects are needed. In addition, continued monitoring remains important given the Taiwanese government has modified their farmland rodent control policy to gradually reduce free AR supplies since 2015.
... Rodenticides are currently the dominant pest control measure, but misuse or overuse of chemicals may cause widespread poisoning of non-target wildlife, as well as the secondary poisoning of predators (Berny, 2007;Jacquot et al., 2013). Accordingly, more ecologically safe measures are essential to manage rodent pest populations. ...
Biological pest control is gaining greater acceptance as an important part of integrated pest management for sustainable agriculture. However, knowledge regarding biological control of rodent pests is limited, and its effectiveness in temperate areas has not been quantified. In traditional Japanese apple orchards, the Ural owl Strix uralensis breeds in tree hollows and preys on the Japanese field vole Microtus montebelli , a native pest species that can harm fruit production. In this study, we hypothesised that the Ural owl, a generalist predator, can act as a biological control agent by reducing vole densities in temperate orchards.
To quantify the pest control effects of breeding Ural owls, we first analysed the diet of individual owls nesting in apple tree hollows. Second, we installed nest boxes in orchards to attract breeding owl pairs and collected data on vole population changes around owl nests to compare with control areas. The population changes were analysed using a generalised linear mixed model to assess the effect of breeding owls within their breeding territory. The model considered seasonal fluctuations in vole population size as well as surrounding land‐use. We also examined vole populations around the owl nests in April, and the distance between nests and forested areas, to determine if these variables influenced nest site selection.
Voles were the primary prey of Ural owls breeding in orchards and the owls reduced vole populations within their estimated breeding territories by 63% (± SE : 53%–70%) compared with the predicted density without owls. Owls preferred to nest in orchards with higher vole population densities in April. Our findings also indicate that higher occupancy rates are possible by distributing nest boxes based on Ural owl breeding territory size (306 m radius circle in our study).
Synthesis and applications . As breeding Ural owls provide significant pest control effects within their breeding territories, the reintroduction of breeding Ural owl pairs within orchards would contribute to rodent pest control. Promoting the reproduction of native raptors in agricultural areas can be an option for developing integrated pest management while simultaneously maintaining regional biodiversity.
... Furthermore, anticoagulant rodenticide residues regularly occur in mammalian predators like foxes (Berny et al. 1997;Beklova et al. 2007;Sage et al. 2010;Tosh et al. 2011;Sanchez-Barbudo et al. 2012), stoats, weasels, andpolecats (McDonald et al. 1998;Shore et al. 2003). Beside ample data on the presence or absence of residues, some studies confirm (Jacquot et al. 2013) or suspect (Newton et al. 1997) population decreases in nontarget species due to anticoagulant rodenticide poisoning. Residues of mainly second-generation anticoagulant rodenticides were present in 60% of foxes (Geduhn et al. 2015) and 55% of barn owls (Geduhn et al. 2016) in Germany in 2011-2014, and density of farmland (livestock density) and urban areas was positively correlated to rodenticide exposure of foxes. ...
Anticoagulant rodenticides are used worldwide to control commensal rodents for hygienic and public health reasons. As anticoagulants act on all vertebrates, risk is high for unintentional poisoning of terrestrial and aquatic wildlife. Causative associations have been demonstrated for the unintended poisoning of terrestrial nontarget organisms. However, behavior and fate of anticoagulant rodenticides in the aquatic environment have received minimal attention in the past despite considerable acute toxicity of several anticoagulants to aquatic species such as fish. In light of recent regulatory developments in the European Union concerning rodenticides, we critically review available information on the environmental occurrence, fate, and impact of anticoagulant rodenticides in the aquatic environment and identify potential risks and routes of exposure as well as further research needs. Recent findings of anticoagulant rodenticides in raw and treated wastewater, sewage sludge, estuarine sediments, suspended particulate matter, and liver tissue of freshwater fish in the low ng/L and µg/kg range, respectively, demonstrate that the aquatic environment experiences a greater risk of anticoagulant rodenticide exposure than previously thought. While the anticoagulant’s mechanism of action from the molecular through cellular levels is well understood, substantial data gaps exist regarding the understanding of exposure pathways and potential adverse effects of chronic exposure with multiple active ingredients. Anticoagulants accumulating in aquatic wildlife are likely to be transferred in the food chain, causing potentially serious consequences for the health of wildlife and humans alike.
... The control of small mammal intermediate hosts in order to limit E. multilocularis transmission has never been attempted except where they are agricultural pests and for that reason (Delattre and Giraudoux, 2005). Poisoning campaigns (using anticoagulant drugs, such as bromadiolone) raise inacceptable environmental and conservation issues, especially if applied on such a large scale they are effective by both decreasing small mammal populations and leading to secondary poisoning of foxes (or dogs) that prey on intoxicated small mammals (Coeurdassier et al., 2014;Jacquot et al., 2013;Raoul et al., 2003). Modifications of the landscape through various modalities of land use have been shown to enhance or conversely to limit the occurrence of high densities of those small mammals which are intermediate hosts for E. multilocularis (Delattre et al., 1992;Giraudoux, 1991;Graham et al., 2004;Wang et al., 2006;Wang et al., 2004). ...
... The delayed action of ARs, inherent to its mechanism, allows rodents to eat several times the LD50 dose between the first bait intake and the death [1] and may as well increase the risk of secondary exposition. Pesticide usage has been correlated with non-target wildlife exposition [74,75], and the intensity of treatment was related to incidence on local fox populations in France [80]. Finally, the diet is certainly going to influence secondary exposition and species like raptors, foxes and mustelids largely feeding on rodents when abundant are consequently the most at risk, as demonstrated for the red kite (Milvus milvus) [81]. ...
... The delayed action of ARs, inherent to its mechanism, allows rodents to eat several times the LD50 dose between the first bait intake and the death [1] and may as well increase the risk of secondary exposition. Pesticide usage has been correlated with non-target wildlife exposition [74,75], and the intensity of treatment was related to incidence on local fox populations in France [80]. Finally, the diet is certainly going to influence secondary exposition and species like raptors, foxes and mustelids largely feeding on rodents when abundant are consequently the most at risk, as demonstrated for the red kite (Milvus milvus) [81]. ...
... For 37.5% of the fecal samples, the DNA was amplified and analysed with DNA amplification techniques described in Dinkel et al. (2011). The results showed that 77% of those samples were faeces from red foxes (Vulpes vulpes) and 18% from cats (Felis silvestris) (Jacquot, 2013;Jacquot et al., 2013). ...
... Non-lethal effects and indirect mortality caused by ARs such as increased susceptibility to parasites, pathogens and other stressors, lethargy and reduced escape responses, may account for a significant impact on the populations (Cox and Smith, 1992;Lemus et al., 2011;Serieys et al., 2015). Impacts of ARs on the population status of predators have not been quantified, but studies indicate negative impacts of ARs at population scale (Jacquot et al., 2013;Coeurdassier et al., 2014;Nogeire et al., 2015). ...
When anticoagulant rodenticides (ARs) are used to control rodent populations there is also a widespread secondary exposure of non-target predators to ARs. To reduce secondary exposure, regulatory restrictions in AR usage were tightened in Denmark in 2011. The restrictions included the cessation of AR use for plant protection and any use away from buildings, as well as limitations in private consumers' access to ARs. To quantify and evaluate the efficiency of the regulatory measures to reduce secondary exposure, we analysed ARs in liver tissue from 40 stone martens (Martes foina) and 40 polecats (Mustela putorius) collected before and 31 stone martens and 29 polecats collected after the restrictions were imposed. No declines in the prevalence ARs were detected following the regulatory restrictions in either stone marten (Before: 98%, After: 100%) or polecat (Before: 93%, After: 97%). The total AR concentration was higher in stone martens than in polecats in both sampling periods. Between the two sampling periods, the total AR concentrations in the mustelids increased (P<0.001). The increase was significant for stone marten (Before: 419ng/g ww, After: 1116ng/g ww, P<0.001), but not for polecat (Before: 170ng/g ww, After: 339ng/g ww). Overall, the total AR concentration was positively correlated to the urban area and the area used for Christmas tree production in which ARs were regularly used before 2011. The regulatory restrictions in AR usage did not reduce exposure of non-target stone martens and polecats. The temporal and spatial patterns of AR concentrations in predators indicate that chemical rodent control in and around buildings is the dominant source for the exposure of non-target predators in intensively human-dominated landscapes in Denmark. The results suggest that non-chemical methods for rodents control at buildings are necessary to prevent widespread secondary AR exposure of predators in human modified landscapes.
... Nevertheless, the use of such molecules, excessively persistent, exacerbated the risk of primary and secondary poisoning of nontarget species (Caloni, Cortinovis, Rivolta, & Davanzo, 2016;Hughes, Sharp, Taylor, Melton, & Hartley, 2013;Jacquot et al., 2013). Therefore, such molecules should be carefully used. ...
Anticoagulant rodenticides are commonly used to control rodent pests worldwide. They specifically inhibit the vitamin K epoxide reductase (VKORC1), which is an enzyme encoded by the Vkorc1 gene, involved in the recycling of vitamin K. Therefore, they prevent blood clotting. Numerous mutations of Vkorc1 gene were reported in rodents, and some are involved in the resistant to rodenticides phenotype. Two hundred and sixty-six mice tails were received from 65 different locations in France. Coding sequences of Vkorc1 gene were sequenced in order to detect mutations. Consequences of the observed mutations were evaluated by the use of recombinant VKORC1. More than 70% of mice presented Vkorc1 mutations. Among these mice, 80% were homozygous. Contrary to brown rats for which only one predominant Vkorc1 genotype was found in France, nine missense single mutations and four double mutations were observed in house mice. The single mutations lead to resistance to first-generation antivitamin K (AVKs) only and are certainly associated with the use of these first-generation molecules by nonprofessionals for the control of mice populations. The double mutations, probably obtained by genetic recombination, lead to in vitro resistance to all AVKs. They must be regarded as an adaptive evolution to the current use of second-generation AVKs. The intensive use of first-generation anticoagulants probably allowed the selection of a high diversity of mutations, which makes possible the genetic recombination and consequently provokes the emergence of the more resistant mutated Vkorc1 described to date.
... B. Rodent abundance index. Red fox (Vulpes vulpes) numbers are known to follow rodent numbers, and such data have been used to analyse rodent cycles in Norway 40 and elsewhere41 . ...
Supplementary Figures 1-3, Supplementary Tables 1-4, Supplementary Notes 1-3 and Supplementary References
... This problematic trait of 'catastrophic predation' could paradoxically also represent an Achilles' heel for cat management by strategically poisoning cats through their intrinsic predatory behaviour. Inadvertent secondary poisoning of native predators consuming prey that have either died or are dying from pesticide poisoning is a significant negative consequence of pest control worldwide (Colvin et al. 1988; Brakes and Smith 2005; Berny 2007; Jacquot et al. 2013). Although feral cats may succumb to secondary poisoning after rabbit-or rodentbaiting programs (Heyward and Norbury 1999; Alterio 2000; Nogales et al. 2004), their deliberate targeting through secondary poisoning has rarely been implemented (Alterio 1996; Morris et al. 2004). ...
Predation, along with competition and disease transmission from feral domestic cats (Felis catus), poses the key threat to many in situ and reintroduced populations of threatened species globally. Feral cats are more challenging to control than pest canids because cats seldom consume poison baits or enter baited traps when live prey are readily available. Novel strategies for sustainably protecting threatened wildlife from feral cats are urgently required. Emerging evidence suggests that once they have successfully killed a challenging species, individual feral cats can systematically eradicate threatened prey populations. Here we propose to exploit this selective predation through three targeted strategies to improve the efficacy of feral cat control. Toxic collars and toxic implants, fitted or inserted during monitoring or reintroduction programs for threatened species, could poison the offending cat before it can effect multiple kills of the target species. A third strategy is informed by evidence that consumption of prey species that are relatively tolerant to natural plant toxins, can be lethal to more sensitive cats. Within key habitats of wildlife species susceptible to cat predation, we advocate increasing the accessibility of these toxins in the food chain, provided negative risks can be mediated. Deliberate poisoning using live and unaffected 'toxic Trojan prey' enables ethical feral cat management that takes advantage of cats' physiological and behavioural predilection for hunting live prey while minimising risks to many non-targets, compared with conventional baiting.
... Direct bait intake by non-target animals results in primary poisoning, which has been shown for several non-target rodent and shrew species [4][5][6], whereas secondary poisoning happens when predators ingest poisoned prey [7]. A reduction of red fox (Vulpes vulpes) population density has been shown in France after bromadiolone applications in open areas against water voles (Arvicola terrestris) [8,9]. In Canada, fox density was significantly lower in areas where ARs were used to control Richardson's ground squirrels (Spermophilus richardsonii) than in control areas [10]. ...
Anticoagulant rodenticides (ARs) are commonly used to control rodent infestations for biocidal and plant protection purposes. This can lead to AR exposure of non-target small mammals and their predators, which is known from several regions of the world. However, drivers of exposure variation are usually not known. To identify environmental drivers of AR exposure in non-targets we analyzed 331 liver samples of red foxes (Vulpes vulpes) for residues of eight ARs and used local parameters (percentage of urban area and livestock density) to test for associations to residue occurrence. 59.8% of samples collected across Germany contained at least one rodenticide, in 20.2% of cases at levels at which biological effects are suspected. Second generation anticoagulants (mainly brodifacoum and bromadiolone) occurred more often than first generation anticoagulants. Local livestock density and the percentage of urban area were good indicators for AR residue occurrence. There was a positive association between pooled ARs and brodifacoum occurrence with livestock density as well as of pooled ARs, brodifacoum and difenacoum occurrence with the percentage of urban area on administrative district level. Pig holding drove associations of livestock density to AR residue occurrence in foxes. Therefore, risk mitigation strategies should focus on areas of high pig density and on highly urbanized areas to minimize non-target risk.
... Les habitats fréquentés par ces espèces sont diversifiés. Elles utilisent intensément les milieux boisés : les éléments linéaires (haies) pour leurs déplacements et les surfaces boisées (bosquets, forêts) pour leurs gîtes et lieux de reproduction (JACQUOT et al., 2013). Des paysages très structurés sont donc naturellement riches en prédateurs de ce type et exercent indirectement un rôle régulateur sur les populations de campagnols (HANSSON et NILSSON, 1975 Dans certains paysages homogènes tels que la toundra au Groenland et en Scandinavie, les dynamiques de population de certains rongeurs (lemmings et campagnols) présentent des pullulations pluriannuelles qui sont entièrement déterminées par la prédation (GILG et al., 2003 ;HANSKI et al., 2001). ...
In order to identify the habitat types that favour water vole outbreaks, it is important to characterise the links that exist between landscape composition, land use, and outbreak risk Using data obtained during water vole population monitoring efforts carried out in the Puy-de-Dome and Cantal departments from 1985 to 2001, 3 major classes of vole population dynamics were identified and characterised. They are the following: 0 zones of low outbreak risk, which are dominated by fields of arable crops or mosaics of grasslands and croplands (ratio of land under permanent grass to usable agricultural area of <0.75); ii) zones of intermediate outbreak risk (characterised by localised outbreaks), which are dominated by permanent grasslands associated with large forested areas; and iii) zones that experience frequent and severe outbreaks, which are almost entirely dominated by permanent grasslands located within open landscapes. These results match those found in Franche-Comte.
Rodent outbreaks have, in historical memory and at more or less regular intervals, massively affected crops and stored goods locally and sometimes even regionally. The Jura Massif is known, among other things, for its cheese specialties with several emblematic protected designations of origin (PDO), such as Comté, Morbier, Mont‐d'or and Bleu de Gex. In the 1950s, in this region of medium‐altitude mountains, grassland covered between 20% and almost 75% of farmland, regardless of altitude. From the early 1980s to the mid‐1990s, population demographic monitoring of small mammals was carried out in the Septfontaines and Le Souillot area, covering nearly 20,000 hectares. It has been suggested that predation is a major driver of fluctuations in rodent populations. It has taken about 30 years to describe and understand the factors that determine vole outbreaks in the Jura Massif in PDO grassland areas and to establish the basis for controlling them.
El control biológico de roedores por depredación en ecosistemas agrícolas, se ha sugerido desde hace varias décadas como una alternativa sostenible al uso generalizado de rodenticidas
anticoagulantes por su menor impacto ambiental.
La depredación es un componente clave en la dinámica poblacional de muchas especies de micromamíferos y su utilización como agente de control biológico agrícola, requiere seleccionar depredadores cuyas poblaciones puedan ser atraídas con facilidad y que a su vez por su respuesta funcional sean capaces de estabilizar las poblaciones de
micromamíferos para reducir los daños agrícolas.
Las aves rapaces que nidifican en cavidades pueden ser considerados óptimos agentes biológicos, ya que sus abundancias tienden a incrementarse rápidamente mediante la instalación de cajas nido y posaderos, especialmente en ambientes agrícolas donde la disponibilidad de cavidades naturales para nidificar suele ser escasa.
En esta tesis doctoral, evaluamos la capacidad del control biológico del topillo campesino (Microtus arvalis), favoreciendo la presencia de dos depredadores, uno generalista y otro especialista, con alta capacidad de movilidad: el cernícalo vulgar (Falco tinnunculus) y la lechuza común (Tyto alba), en regiones de la península Ibérica donde se han registrado explosiones demográficas recurrentes de topillos campesinos, que han estado asociadas con daños agrícolas y en algunas regiones con problemas sanitarios por tularemia.
El control biológico por depredación puede ser considerado como una técnica prometedora dentro de los planes de manejo ecológico de plagas de roedores, Ecologically-based rodent pest
management (EBRM), basados en la búsqueda de tratamientos donde se prioriza el conocimiento ecológico de la especie que causa el daño, dentro de un marco de aplicación ambiental, cultural y
económicamente sostenible. Sin embargo, es necesario tener en cuenta que los depredadores pueden producir efectos adversos sobre otras especies no diana, incluyendo especies cinegéticas,
bien por depredación directa o por que la especie presa modificaomportamiento para compensar el aumento en el riesgo de depredación.
Los depredadores pueden también ser un componente clave en la dinámica de trasmisión de numerosas enfermedades, aunque por dos mecanismos principales excluyentes. Por un lado, los depredadores pueden extraer individuos enfermos de las poblaciones, lo que reduciría la prevalencia de la enfermedad, pero por otro lado también pueden inducir estres e inmunosupresión
a sus presas, lo que podría favorecer la trasmisión del patógeno. En la península Ibérica, las plagas de topillo campesino están asociadas a un aumento en el número de casos de tularemia en seres humanos. En esta tesis evaluamos que papel podría ejercer la depredación la dinámica de trasmisión de la tularemia en unos de sus principales reservorios, el topillo campesino.
Nuestros resultados mostraron que la instalación de cajas nido para cernícalos y lechuzas en ambientes agrícolas, tuvo la capacidad de reducir significativamente la abundancia tanto del topillo campesino como del topillo mediterráneo (Microtus duodecimcostatus), en cultivos de alfalfa y frutales. También hallamos una menor abundancia de topillos campesinos en las proximidades de las cajas nido ocupadas, siendo el efecto más intenso a mayor proximidad a la caja. Respecto a efectos sobre otras especies de aves, encontramos que la instalación de cajas nido produjo una disminución
en las abundancias dos especies de aves comunes en ambientes agrícolas, la lavandera boyera (Motacilla flava) y la lavandera blanca (Motacilla alba). También observamos un crecimiento
poblacional más lento en el caso de la urraca común (Pica pica), en las zonas con cajas nido respecto de las zonas control. Es recomendable que estos resultados se tengan en cuenta cuando se considera la aplicación de esta técnica de control de roedores, en áreas donde puedan aparecer presas potenciales de las aves rapaces que estén catalogadas como especies amenazadas, como el
caso de la alondra de Dupont (Chersophilus duponti). Sin embargo, conviene mencionar que el control biológico puede ser considerado como una estrategia de control mucho menos dañina sobre otras especies que los rodenticidas anticoagulantes, cuyo impacto negativo sobre la comunidad de
depredadores es muy elevado.
Considerando los posibles efectos del control biológico sobre una especie cinegética, en esta tesis estudiamos los efectos de la depredación sobre la detectabilidad de la perdiz roja (Alectoris rufa), considerando tres métodos de censo, puntos de conteo y escucha,
transectos lineales por vehículo y transectos lineales a pie. Nuestros resultados mostraron que en aquellos casos donde la presión depredatoria sobre las perdices fue mayor, la detectabilidad de la especie se vio afectada, siendo este efecto mayor cuando el método de censo utilizado no permite contabilizar individuos por señales acústicas.
Respecto a la dinámica de la trasmisión de la tularemia, nuestros resultados mostraron que, durante un periodo de alta densidad de topillos, los depredadores no seleccionaron favorablemente topillos infectados. Sin embargo, la prevalencia de tularemia fue mayor en las proximidades de las cajas
nido, siendo este estudio la primera vez que se observa que la depredación favorece la prevalencia de la tularemia en poblaciones cíclicas de roedores.
No se registraron caso de tularemia en humanos en los municipios con mayor prevalencia en topillos, lo que sugiere que otros factores como la abundancia de vectores, la presencia de topillos muertos en el paisaje o la propagación a través de
aerosoles o red hidrográfica podrían estar involucrados en la epidemiología de la tularemia en humanos
This thesis addressed marine vegetation changes in the shallow rocky shores of the Montgrí Illes Medes and Baix Ter Natural Park integrating the macroalgal and sea urchin dynamics in front of natural and human-related impacts, and the role and effectiveness of Marine Protected Areas and restoration actions as conservation tools at lower trophic levels.
Besides, since most of this thesis is based on long-term monitoring data, a valuable baseline of the algal community’s structure and functioning was provided here which could be vital to predict and detect ecological changes that could jeopardize the preservation of marine forests.
The present study aims to compare in vitro the pharmacodynamics characteristics between diastereoisomers of each of the three SGARs, bromadiolone, difenacoum, and difethialone toward VKORC1 of field voles (Microtus arvalis) and European water voles (Arvicola terrrestris) expressed in a yeast Pichia pastoris. Ki values were obtained from at least from two separate experiments
Second generation anticoagulant rodenticides (SGAR) are generally highly efficient for rodent management even towards warfarin‐resistant rodents. Nevertheless, because of their long tissue‐persistence, they are very associated with non‐target exposure of wildlife and have been identified as “Candidates for Substitution” by the European Union’s competent authority. A promising way to reduce ecotoxicity issues associated to SGAR could be the improvement of SGAR based on their stereoisomery and due to this improvement positioning about SGAR might be reconsidered.
This article is protected by copyright. All rights reserved.
Both target and non-target small mammals are exposed to rodenticides (AR). A better understanding of the drivers controlling this exposure is critical for the conservation of threatened small mammal species but also because they may represent important pathways of poisoning for birds of prey and carnivore mammals. Here, we consider the spatial components involved in the process of small mammal exposure to ARs with the aim to address how these can be used in spatially explicit risk assessment. We present how various drivers operate on multiple spatial scales. On continental and/or regional scales, both biogeographical distribution of small mammals and other species of conservation value and international/national regulations of AR applications (indoor vs outdoor…) could be used to identify some countries or states where exposure is more likely. For application at the local scale (i.e. few km²), we reviewed published studies that analysed the spatial pattern of small mammal exposure to ARs according to species and distance to treatments. We evidence that most of the small mammals exposed to AR are found in the immediate vicinity of treatment areas, i.e., within 100 m. Over 100 m, exposed rodents are rare but can be found until 750 m distance from treatment areas. Species traits related to spatial dimension such as habitat preferences, home range size and mobility also influence exposure. Exposure is variable, in terms of proportion of contaminated individuals and levels of residues, for species showing small home-range size and a limited spatial mobility. The level of exposure depends on whether the main habitat of the given species is similar or not to the one of the target rodent. For instance, exposure of the common vole, a grassland species, is low when ARs are used indoor while it can be highly exposed when bromadiolone is applied outdoor to control the water vole, a sympatric species. For small mammals exhibiting a relatively large home-range size and a high spatial mobility such as the wood mouse and the bank vole, the exposure is commonly reported within a lower range than target species. Although this has not been studied in details, we also address how landscape and/or habitat features may modulate exposure, suggesting that landscape management may help to mitigate the risk of ARs to small mammals. Finally, we discuss both the advantages and disadvantages of statistical, analytical or simulation models to assess potential or actual exposure of NTSM to AR in a spatially explicit way. We conclude that in order to analyse global patterns in usage and exposure risks, large scale statistical modelling should be used while for detailed site specific assessments, simulation models may be more appropriate.
In recent years anticoagulant rodenticides have emerged as an important factor reducing the survival of many birds of prey and some predatory mammals. Understanding the ecological factors driving the exposure of predators is a key component in assessing the risk posed by anticoagulant rodenticides. We have reviewed the literature to better understand and synthesize the ecological factors driving AR exposure in predators, focusing on landscape and environmental management, traits of the exposed predators and the most common exposure pathways. On a global scale, the large input of ARs into urban and agricultural settings, and the relatively large footprint of these landscapes, has led to widespread AR exposure of many species, ranging from insects to large carnivores. General inferences can be made with regards to the traits of the most affected species. We determined that at-risk predators tend to be nocturnal opportunistic species for which rodents are a key dietary component, seasonally or year-round. They also tend to be non-migratory and occupy habitats within, or in close proximity to landscapes that are heavily influenced by human activities such as intensive agriculture or urban areas. Predators that consume rats in urban environments are disproportionately affected by ARs. As our understanding of how ARs are transferred up the food-chain is still limited, there is a need to further comprehend the extent to which non-target prey are being exposed to ARs in different landscapes, as we are frequently documenting AR residues in predators that do not typically prey on rodents. We recommend a focus on urban landscapes, where to date no exposure data has been collected on non-target prey. We also have a very limited understanding of non-target prey exposure in the urban-wildland/agricultural interface where opportunistic predators are known to hunt both habitat types interchangeably. Finally, we need to decipher whether the mounting evidence of exposure in predators translates into any population level effects.
Anticoagulant rodenticides (ARs) are currently the most common pesticides and biocides used to control rodents. The long-term persistence in animal tissues of the second-generation compounds (SGARs) causes their bioaccumulation in predatory species. In this chapter, we evaluate some of the key parameters that are likely to determine bioaccumulation and risk in wildlife from secondary exposure to ARs, review wildlife field monitoring studies from around the world to assess the scale of that exposure, and examine the current state of knowledge as to how secondary exposure relates to risk of mortality and other adverse effects in wildlife and in humans. Using a simple modelling approach and information from the published literature, we conclude that excretion rate is key in determining the extent of bioaccumulation and resultant risk in wildlife from secondary exposure to SGARs. We also find that secondary exposure in predators is widespread and widescale throughout the world, and may be greatest in predatory mammals that specialise on feeding on rodents. The extent of secondary [lethal and sub-lethal] poisoning that results is unclear. This is largely because unequivocal diagnosis of AR-mediated mortalities is not easy to determine from necropsy and there is no clear threshold residue that is diagnostic of effect, although recent development of probabilistic modelling of residue data may help in the future. We recommend that the direct consequences for predators from AR exposure, and the potential consequent impacts on the top-down regulation of rodent populations, deserve greater study.
La structure et l’intensité des interactions ressources-consommateurs qui forment les réseaux trophiques régulent une très grande partie des transferts de biomasse mais aussi de contaminants biologiques et chimiques dans les écosystèmes. L’objectif de la thèse est de développer des modèles permettant d’étudier les mécanismes de transport des contaminants et d’évaluer ainsi d’une part la dynamique des maladies infectieuses et des pollutions chimiques, et d’autre part les réponses des réseaux trophiques soumis à ces contaminations.[...] À l’issue de ces travaux, une quatrième étape de la thèse a été d’intégrer les interactions trophiques, les dynamiques des parasites et les impacts des pollutions dans des méta-écosystèmes (i.e. avec dispersions d’individus entre écosystèmes). En utilisant la théorie des matrices aléatoires nous avons établi des mesures des risques d’émergence de parasites que nous avons évalués en fonction des perturbations extérieures.L’étude a ainsi montré que ces perturbations augmentent les risques épidémiques, mais que ces risques pouvaient être réduits par la dispersion des individus (sains et infectés) sous certaines conditions qui sont,par exemple pour les TTP, un nombre d’espèces plus grand que le nombre d’écosystèmes connectés, et un taux de virulence plus faible que le taux de contagion.Ainsi, dans un contexte planétaire d’augmentation des pressions anthropiques sur les écosystèmes,cette thèse de modélisation apporte un ensemble d’outils et de développements conceptuels permettant d’analyser quantitativement et qualitativement les transferts et les impacts des contaminants sur les écosystèmes.
The European red fox Vulpes vulpes represents a continuing threat to both livestock and native vertebrates in Australia, and is commonly managed by setting ground‐level baits impregnated with 1080 (sodium fluoroacetate) poison. However, the long‐term effectiveness of such control campaigns is likely to be limited due to the ability of foxes to disperse over considerable distances and to swiftly recolonize areas from where they had been removed.
To investigate the effectiveness of fox baiting in a production landscape, we assessed the potential for foxes to reinvade baited farm property areas within the jurisdiction of the Molong Rural Lands Protection Board (RLPB), an area of 815 000 ha on the central tablelands of New South Wales, Australia. The spatial distribution and timing of fox baiting campaigns between 1998 and 2002 was estimated from RLPB records and mapped using Geographical Information System software. The effectiveness of the control campaign was assessed on the basis of the likely immigration of foxes from non‐baited farms using immigration distances calculated from published relationships between dispersal distance and home range size.
Few landholders undertook baiting campaigns in any given year, and the area baited was always so small that no baited property would have been sufficiently far from an unbaited property to have been immune from immigrating individuals. It is likely, therefore, that immigration onto farms negated any long‐term effects of baiting operations. This study highlights some of the key deficiencies in current baiting practices in south‐eastern Australia and suggests that pest management programmes should be monitored using such methods to ensure they achieve their goals.
splm is an R package for the estimation and testing of various spatial panel data specifications. We consider the implementation of both maximum likelihood and generalized moments estimators in the context of fixed as well as random effects spatial panel data models. This paper is a general description of splm and all functionalities are illustrated using a well-known example taken from Munnell (1990) with productivity data on 48 US states observed over 17 years. We perform comparisons with other available software; and, when this is not possible, Monte Carlo results support our original implementation. PLEASE NOTICE JSS IS OPEN ACCESS: download from jstatsoft.org, this is vol. 47/1
A method to estimate the abundance of the fossorial form of the water vole Arvicola terrestris scherman (Shaw, 1801) has been developed, by using surface indices. Results are compared to the standard method of estimation using trap lines. These results show quantitatively that it is possible to differentiate reliably mole indices from water vole indices. Moreover, the two species are inclined to exclude each other. Even though water voles share the same galleries as moles, specific surface indices of the water vole occur for any density exceeding 2 ind/trap line (over 20 ind/ha). Several models of abundance estimation are put forward, all of them using linear multiple regressions. Correlations between the estimations from indices and the estimations from trap lines exceed 0.8 and the limits of using abundance classes are tested. Other limits are developed in the discussion. One of them is that the sampling intervals are saturated for densities exceeding 400 ind/ha. The index method, which is easy to carry out, offers the definite advantage of being suitable to space and time scales otherwise incompatible with estimations from trap lines. For instance, it allows distribution maps from wide transects about areas of more than 25 km(2) to be drawn, in less than two days.
Poison operations to control or eradicate exotic mammals are a key component of conservation management in the South Pacific. They also result in by-kill of native species. It is therefore important to develop reliable methods for estimating by-kill and assessing its impact. The North Island saddleback (Philesturnus carunculatus rufusater), a rare New Zealand forest bird, was reintroduced to Mokoia Island in 1992, and 4 years later there was an aerial drop of cereal pellets containing Brodifacoum aimed at eradicating mice. We used mark–recapture analysis on resighting data collected from 1992 to 1997 to estimate the by-kill of saddlebacks attributable to this poison drop. We nominated a set of candidate models to explain the data, and compared these using Akaike's Information Criterion. The analysis showed that saddleback survival was substantially lower than expected in the 6-week interval after the poison drop, taking age, density dependence, season and random variation into account. Taking expected survival rates into account, the probability of an adult being killed was estimated to be 0.45 (95% CI=0.34–0.56), and the probability of a juvenile being killed was estimated to be 0.35 (95% CI=−0.05–0.75). We then used a simulation model developed for the population to assess the longer-term impact of this mortality. While the mortality set back the expansion of the population by 1–2 years, we predicted that the population would have recovered fairly quickly and ultimately reach the same carrying capacity. Mark–recapture analysis permits precise estimates of background survival rates unconfounded by seasonal or random variation.
In 1996 an eradication operation against two species of rats (Rattus norvegicus and R. exulans was conducted on Kapiti Island (1965 ha) and its small offshore islands. Trials with non-toxic baits had been carried out to help determine the risks to non-target species, and research was undertaken to collect baseline data for measuring the response of vegetation, invertebrates, reptiles and birds to the removal of rats. Talon 7-20 bait (containing 0.002% brodifacoum) was distributed over Kapiti Island in September and October by helicopter and by hand, while bait stations were used on the offshore islands. Impacts on birds and reef fish were investigated. Although there were non-target bird deaths as a result of the poisoning operation, post-eradication monitoring indicated that the toxin had no deleterious effect on breeding and most losses would be rapidly made up by recruitment of new individuals into the breeding population. There was no evidence that reef fish were negatively affected. The successful removal of rats has apparently resulted in a significantly improved survival rate for stichbirds (Notiomystis cincta) and saddlebacks (Philesturnus carunculatus). Benefits to other taxa are expected and will be documented as follow-up studies are completed.
RESUME : Créé en 1986 par l'Office national de la chasse (ONCFS), le réseau SAGIR est un système national de surveillance sanitaire de la faune sauvage. Il est basé sur un partenariat entre l'ONCFS, l'Agence française de sécurité sanitaire des aliments de Nancy, le Laboratoire de toxicologie de l'Ecole nationale vétérinaire de Lyon, les Laboratoires vétérinaires départementaux et les Fédérations départementales de chasseurs. En treize ans d'existence, SAGIR a permis de mettre en évidence de nouvelles maladies, de collecter de nombreuses données sur la pathologie de la faune sauvage et de suivre plusieurs épisodes de mortalité massive. Depuis quelques années, le réseau SAGIR est de plus en plus souvent associé à des programmes concernant l'interface sanitaire faune sauvage/animaux domestiques. Malgré plusieurs biais qui empêchent le réseau SAGIR d'être un véritable réseau d'épidémiosurveillance, le réseau SAGIR reste un outil précieux. SUMMARY : Created in 1986 by the Office national de la chasse (ONCFS), the SAGIR network is a national system of surveillance of wildlife diseases. It is organized as a partnership between the ONCFS, the French Agency for food sanitary security of Nancy, the toxicology laboratory of the national Veterinary School in Lyon, the departmental veterinary laboratories and the departmental hunters' federations. During its thirteen years of life, SAGIR has permitted to highlight new diseases, to collect numerous data on wildlife pathology and to monitor several important die-off. Since a few years, SAGIR has been more and more often associated to programs dealing with the sanitary relationship between wildlife and livestock. In spite of several biases which prevent the SAGIR network to be a true epidemiosurveillance network, the SAGIR remains a precious tool.
The impacts of rodents in both developing and developed countries are legendary. Myths and dogma about rodents and their outbreaks abound. They are imbedded in the culture and language of many societies. In many instances, it is the acceptance of these outbreaks by society that is our greatest challenge as crop protection specialists or conservation biologists. The reason these episodic outbreaks become etched in the socio-cultural psyche from the sparsely populated uplands of Laos to the considerably more affluent agricultural lands of Europe is that the impacts are often staggering—economically, socially, and even politically. This book is a collation of contributions from Asia, Africa, Oceania (Australia and New Zealand), Europe, and North America. The advent of Ecologically Based Rodent Management (EBRM) has stimulated the progress summarized in this book. The contributions provide a modern appraisal to an age-old problem through a better understanding of the mechanisms that lead to rodent outbreaks, why rodent population numbers increase under different circumstances, and the impact of outbreaks in a range of different agroecosystems and native forests in different parts of the world. This is an encouraging progress report driven by scientists passionate about rodents, about people, about conservation, and about improving our knowledge of these species and the ecosystems they inhabit. And in a novel twist, there is an appendix of recipes for preparing rat meat. You will be more than tempted to try one of these dishes next time you travel in Asia or Africa.
Pesticides are widely used throughout the world to control agricultural pests. Owing to their well identified side-effects on wildlife, the release of high quantities of pesticides to the environment should always require responsible use of both science-based information and the precautionary principle, however decision making in wildlife management and conservation is not systematically supported by scientific evidence. This is particularly worrying when decision making involves release of toxic substances to the environment, as often occurs in rodent plague control. Poorly-informed management decisions to control a rodent plague can adversely affect wildlife, especially when chemical-based treatments are generically designed and applied on a broad scale, with high economic cost. Evidence-based and environmentally sustainable management should be used to control rodent plagues in Spain.
In this paper we consider a panel data model with error components that are both spatially and time-wise correlated. The model blends specifications typically considered in the spatial literature with those considered in the error components literature. We introduce generalizations of the generalized moments estimators suggested in Kelejian and Prucha (1999. A generalized moments estimator for the autoregressive parameter in a spatial model. International Economic Review 40, 509–533) for estimating the spatial autoregressive parameter and the variance components of the disturbance process. We then use those estimators to define a feasible generalized least squares procedure for the regression parameters. We give formal large sample results for the proposed estimators. We emphasize that our estimators remain computationally feasible even in large samples.
Le fonctionnement du cycle parasitaire de l'échinocoque alvéolaire (Echinococcus multilocularis) est étudié en Franche-Comté (France) à travers (i) la distribution des prévalences chez le renard (Vulpes vulpes) au niveau régional, (ii) distribution des cas humains, au niveau régional et (iii) la distribution des rongeurs, du renard, du chat forestier (Felis silvestris et domestique (Felis catus) au niveau du biotope. Cette dernière étude, menée au niveau d'organisation du peuplement et comparée à celles menées aux autres niveaux de perception aboutit à formuler une théorie selon laquelle le cycle de l'échinococcose alvéolaire se maintiendrait en Franche-Comté grâce à un fonctionnement en mosaïque: la parasitose serait temporaire en un secteur donné (= tesselle), la permanence de l'enzootie dans la région étant due à l'alimentation de zones "indemnes' par les zones temporairement favorables et infestées (vecteur principal = renard). Le caractère temporaire de l'infestation d'une tesselle serait dû au fait que convergent un nombre de conditions: abiotiques (mésoclimatologie) et biotiques (cinétique des populations de rongeurs et utilisation par le renard dans une relation prédateur/proie conditionnée par le paysage). L'appréciation du caractère "fonctionnel" de la mosaïque tiendrait donc à l'analyse simultanée de relations et de dynamiques qui s'expriment à des niveaux de perception différents (station : conservation des œufs de Ténia selon les conditions édaphiques et la climatologie saisonnière ; biotope: distribution des peuplements de rongeurs; secteur: cinétique des peuplements de rongeurs dépendant de l'organisation de l'espace agricole; région: mésoclimatologie et arrangement spatial des secteurs).
The functional response of predators to prey density variations has previously been investigated in order to understand predation patterns. However, the consequences of functional response on parasite transmission remain largely unexplored. The rodents Microtus arvalis and Arvicola terrestris are the main prey of the red fox Vulpes vulpes in eastern France. These species are intermediate and definitive hosts of the cestode Echinococcus multilocularis. We explored the dietary and contamination responses of the red fox to variations in prey density. The dietary response differed between the two prey species: no response for M. arvalis and a type III-like (sigmoidal) response for A. terrestris that shows possible interference with M. arvalis. The fox contamination response followed a type II shape (asymptotic) for both species. We conclude that fox predation is species specific and E. multilocularis transmission is likely to be regulated by a complex combination of predation and immunologic factors. These results should provide a better understanding of the biological and ecological mechanisms involved in the transmission dynamics of trophically transmitted parasites when multiple hosts are involved. The relevance of the models of parasite transmission should be enhanced if non-linear patterns are taken into account.
A common vole (Microtus arvalis) population peak in Northern Spain in 2007 was treated with large scale application of chlorophacinone, an anticoagulant rodenticide of the indandione family. Voles found dead and trapped alive were collected in treated and untreated areas. Residues of chlorophacinone were analyzed in liver of voles by HPLC-UV. Also, the presence of the pathogen Francisella tularensis was analyzed by PCR in samples of vole spleen. Chlorophacinone (82-3800 ng/g; wet weight liver) was only detected in voles found dead in treated areas (55.5%). The prevalence of F. tularensis in voles found dead in treated areas was also particularly high (66.7%). Moreover, chlorophacinone levels were lower in voles that were PCR-positive for F. tularensis (geometric mean [95% CI], 418 [143-1219] ng/g) than in those that were PCR-negative (1084 [581-2121] ng/g). Interactions between pathogens and rodenticides might be considered to reduce the doses used in baits or to avoid the use of the more toxic 2nd generation anticoagulant rodenticides.
Depuis les années 50, les rodenticides anticoagulants sont couramment utilisés pour contrôler les populations de rongeurs commensaux et de prairie. De nombreux empoisonnements de la faune non cible sont répertoriés partout dans le monde. En Europe de l'Ouest notamment, la bromadiolone est utilisée de façon intensive dans les champs. Elle est le seul rodenticide autorisé en France pour contrôler les populations de Campagnol terrestre, Arvicola terrestris Sherman. Ces opérations utilisant des appâts grains de blé enterrés dans le sol sont réalisées à de larges échelles et des dizaines voire des centaines d'empoisonnements secondaires de prédateurs, dont le renard, sont répertoriés chaque année. Cette étude propose d'apporter des éléments de compréhension sur les modalités de son transfert à travers les systèmes biologiques complexes considérés dans leur intégralité.
Le premier objectif a été d'évaluer la variabilité environnementale de la persistance de la bromadiolone dans les appâts en conditions naturelles. Cette persistance dans les galeries de traitement est courte (demi-vie de 3 à 6 jours) et faiblement influencée par les conditions environnementales (type de sol et conditions climatiques). Cependant, elle augmente considérablement lors du stockage des appâts dans des réserves (27<demi-vie<45 jours) et peut constituer un risque d'exposition des rongeurs sur des périodes beaucoup plus longues.
Le second objectif a été d'évaluer la cinétique d'intoxication des populations de rongeurs dans les zones traitées avec dans notre cas comme espèce cible, le Campagnol terrestre, et une espèce non cible, le Campagnol des champs Microtus arvalis. Les résidus de bromadiolone dans les deux populations atteignent des concentrations maximales entre 3 et 5 jours après le traitement en fonction de l'espèce ou des tissus et des valeurs élevées sont maintenues pendant 15 à 20 jours. Cependant, la recolonisation de terriers traités peut induire une exposition de rongeurs jusqu'à 3 mois après la distribution des appâts. Ce phénomène permettrait d'expliquer en partie le fait que des rongeurs présentant des résidus de bromadiolone soient disponibles pour des prédateurs plus de 4 à 6 mois après le traitement.
Le dernier objectif a été d'évaluer la faisabilité de mesurer, en nature, l'exposition de renards par l'analyse des résidus de bromadiolone dans leurs fèces. Une nouvelle méthode analytique en Chromatographie Liquide et Spectrométrie de Masse a été développée pour les dosages. Les résidus en bromadiolone dans les fèces et dans le plasma de renards captifs nourris pendant cinq jours avec des campagnols intoxiqués montrent des évolutions temporelles similaires : une augmentation rapide pendant la phase d'exposition puis une diminution progressive après celle-ci. La bromadiolone a été détectée dans les fèces dès le premier prélèvement 15 heures après la première exposition et pendant toute la durée de l'expérimentation, i.e., 24 jours après la dernière exposition. La dose administrée (1000 µg broma / j) se serait probablement révélée mortelle pour deux des quatre renards exposés sans l'administration d'antidote. Deux expérimentations ont ensuite été menées en nature. La première a montré que 48% des fèces collectées dans une zone traitée entre 15 et 45 jours auparavant, présentaient des résidus de bromadiolone mesurable. La seconde a montré qu'une relation d'ordre exponentiel reliait les résidus de bromadiolone mesurés dans le foie et ceux mesurés dans les contenus rectaux de renards prélevés dans une zone traitée entre un et six mois auparavant.
Ces travaux permettent d'envisager une évaluation indirecte de l'exposition in situ de populations de renards à large échelle spatiale et temporelle. Après l'optimisation de cette méthode de mesure, nous pourrons alors déterminer si différents facteurs environnementaux peuvent moduler cette exposition et cela sans impliquer ni la capture ni la mort de l'animal.
This paper presents the result of a 4 year survey in France (1991-1994) based on the activity of a wildlife disease surveillance network (SAGIR). The purpose of this study was to evaluate the detrimental effects of anticoagulant (Ac) rodenticides in non-target wild animals. Ac poisoning accounted for a very limited number of the identified causes of death (1-3%) in most species. Predators (mainly foxes and buzzards) were potentially exposed to anticoagulant compounds (especially bromadiolone) via contaminated prey in some instances. The liver concentrations of bromadiolone residues were elevated and species-specific diagnostic values were determined. These values were quite similar to those reported in the literature when secondary anticoagulant poisoning was experimentally assessed.
Pesticides are widely used to control agricultural pests. Unfortunately, because of their biological activity, they may have detrimental effects on nontarget species. Acute toxicity, resulting in death, is reported worldwide. Although chronic and indirect effects may be even more hazardous for animal populations on a long-term basis, they are usually evaluated as parts of research programs. The purpose of this paper was to review the wildlife-poisoning surveillance systems and their results regarding the circumstances of exposure of wild animals, the pesticides involved and the species exposed. Most data are retrieved from the British and French pesticide poisoning surveillance systems in wildlife, with some data from other European structures.
Invasive mammals are the greatest threat to island biodiversity and invasive rodents are likely responsible for the greatest number of extinctions and ecosystem changes. Techniques for eradicating rodents from islands were developed over 2 decades ago. Since that time there has been a significant development and application of this conservation tool. We reviewed the literature on invasive rodent eradications to assess its current state and identify actions to make it more effective. Worldwide, 332 successful rodent eradications have been undertaken; we identified 35 failed eradications and 20 campaigns of unknown result. Invasive rodents have been eradicated from 284 islands (47,628 ha). With the exception of two small islands, rodenticides were used in all eradication campaigns. Brodifacoum was used in 71% of campaigns and 91% of the total area treated. The most frequent rodenticide distribution methods (from most to least) are bait stations, hand broadcasting, and aerial broadcasting. Nevertheless, campaigns using aerial broadcast made up 76% of the total area treated. Mortality of native vertebrates due to nontarget poisoning has been documented, but affected species quickly recover to pre-eradication population levels or higher. A variety of methods have been developed to mitigate nontarget impacts, and applied research can further aid in minimizing impacts. Land managers should routinely remove invasive rodents from islands <100 ha that lack vertebrates susceptible to nontarget poisoning. For larger islands and those that require nontarget mitigation, expert consultation and greater planning effort are needed. With the exception of house mice (Mus musculus), island size may no longer be the limiting factor for rodent eradications; rather, social acceptance and funding may be the main challenges. To be successful, large-scale rodent campaigns should be integrated with programs to improve the livelihoods of residents, island biosecurity, and reinvasion response programs.
Resumen: Los mamíferos invasores son la mayor amenaza a la biodiversidad insular, y los roedores invasores son probables responsables de la mayoría de las extinciones y cambios en los ecosistemas. Las técnicas para la erradicación de roedores de las islas fueron desarrolladas hace 2 décadas. Desde entonces ha habido un desarrollo y aplicación significativa de esta herramienta de conservación. Revisamos la literatura sobre erradicaciones de roedores invasores para evaluar su estado actual e identificar acciones para hacerlo más efectivo. Mundialmente, se han efectuado 332 erradicaciones de roedores exitosas, identificamos 35 erradicaciones fracasadas y 20 campañas con resultados desconocidos. Los roedores Invasivos ha sido erradicados de 284 islas (47,628 ha). Con la excepción de dos islas pequeñas, se utilizaron rodenticidas en todas las erradicaciones. Se utilizó Brodifacoum en 71% de las campañas y en 91% de la superficie tratada. Los métodos más frecuentes de distribución de rodenticida (de más a menos) son estaciones de cebo, aplicación manual y aplicación aérea. Sin embargo, las campañas de aplicación aérea abarcaron 76% de la superficie tratada. Se ha documentado la mortalidad de vertebrados nativos debido a envenenamiento accidental, pero las especies afectadas recuperan, o superan, rápidamente los niveles poblacionales previos a la erradicación. Se ha desarrollado una variedad de métodos para mitigar los impactos no deseados, y la investigación aplicada puede ayudar a minimizar los impactos aun más. Los gestores de recursos deben remover rutinariamente a roedores invasores de islas <100 ha que carezcan de vertebrados susceptibles de envenenamiento no deseado. Para islas más extensas y para las que requieren de mitigación de envenenamientos no deseados, se requiere de la consulta de expertos y de mayores esfuerzos de planificación. Con la excepción de Mus musculus, es posible que el tamaño de la isla ya no sea el factor limitante para la erradicación de roedores, más bien, la aceptación social y el financiamiento pueden ser los retos principales. Para ser exitosas, las campañas a gran escala deben estar integradas por programas para mejorar las condiciones de vida de los residentes, de bioseguridad insular y de respuesta a reinvasiones.
Red Kites (Milvus milvus) are avian scavengers limited to Europe, and they currently are listed as an endangered species worldwide. Accidental poisoning is often listed as one of the threats to Red Kites throughout their range of distribution. The purpose of this article is to investigate the suspected poisoning cases reported to the French Wildlife Disease Surveillance System. Dead animals are submitted to a local veterinary laboratory for necropsy and when poisoning is suspected, samples are submitted to the Toxicology Laboratory of the College of Veterinary Medicine, Lyon, France. Over the period 1992-2002, 62 Red Kites suspected of poisoning were submitted, and poisoning was the confirmed cause of death for greater than 80% of these cases. The major toxicants found were cholinesterase inhibitors (carbamates and organophosphate insecticides) and anticoagulant compounds. The circumstances of exposure include secondary poisoning after the use of anticoagulants over vast areas to control water vole (Arvicola terrestric) populations, but they also include malicious poisoning with carbamates (aldicarb and cabofuran) in meat baits. Cases of poisoning vary throughout France, with observed mortality rates ranging between 0.1/100 hundred breeding pairs/10 yr and four cases/100 hundred breeding pairs/10 yr. Additional cases of poisoning likely go undetected, and our results suggest that acute poisoning is not uncommon in Red Kites and that it should be considered in the current restoration plans.
Les dégâts causés aux prairies par les pullulations de campagnols terrestres sont un mal bien connu des agriculteurs, avec un impact économique important sur leurs exploitations. Hélas, les risques engendrés par une lutte quasi exclusivement chimique contre ces rongeurs en sont un autre, et non des moindres, notamment en termes de santé publique et de respect de l'environnement. Une alternative à ce type de lutte était attendue avec impatience à la fois par les exploitants et les défenseurs de la nature. C'est cette alternative que dévoile cet ouvrage, en détaillant, entre autres, le concept de lutte raisonnée. L'enjeu de la démarche exposée dans ce livre, lié à son intégration dans les programmes de recherche et au développement d'outils opérationnels pour les professionnels, dépasse par ailleurs très largement le seul cadre régional des pullulations d'un ravageur comme le campagnol terrestre. C'est pourquoi, cet ouvrage s'adresse non seulement aux acteurs de la lutte contre le campagnol terrestre, mais aussi à toute personne que la recherche agronomique et environnementale concerne ; cette dernière ne pourra en effet pas faire l'économie d'une révision de ses méthodes d'observation pour les adapter aux échelles d'espace et de temps propres aux phénomènes biologiques.
The impact of deliberate culling of fox populations has been much debated. Although a local (< 10 km2) impact has been accepted, previous authors have denied that culling has any impact on a larger scale because local losses are compensated through immigration. Rather, it has been claimed that at this scale fox density is determined by resources, mediated through social behaviour and breeding suppression. We determined the impact of culling on a regional scale (> 1000 km2), using data on culling (Heydon and Reynolds, 2000), fox density (Heydon, Reynolds and Short, 2000) and productivity. The three U.K. study regions (size 1238-2322 km2) were in mid-Wales (A), the east Midlands (B) and East Anglia (C). High productivity in regions A and C was associated with low density, high culling mortality and high overall mortality (all relative to region B), indicating that density was suppressed by culling. In region B (moderate) breeding suppression was associated with a higher density and lower cull than in regions A and C, implying that fox density was closer to the maximum sustainable by resources. We conclude that the impact of culling in different regions of Britain is variable, dependent on the regional prevalence, methods, and history of culling. However, it is clear that in a range of circumstances culling can substantially depress fox numbers, and that current fox densities reflect a history of culling. This conclusion is fundamental in considering the management of fox predation in farming and conservation contexts.
Poisoning by pesticides is considered one of the primary threats to the Red Kite Milvus milvus. We studied the diet of this raptor in an area of eastern France where the rodenticide bromadiolone is widely used to control Water Vole Arvicola terrestris outbreaks. A high degree of specialization for Water Voles was noted, as their remains were identified in all 119 pellets collected in autumn 2008, whereas other small rodent species and insects occurred in 27 and 9% of pellets, respectively. We estimated that Water Voles constituted 94% of the total biomass ingested by Red Kites under these conditions. Based on these data, the risk of secondary poisoning due to feeding on poisoned voles was assessed. Acute exposure on a single day was not considered a risk for Kites, but exposure to poisoned voles over 1 week represented the maximal risk for the Red Kite; the calculated dose of bromadiolone ingested by a Red Kite was 137 times higher than the toxicological benchmark for birds. A field survey in the studied area detected four dead Red Kites and one moribund bird in autumn 2008 but did not confirm that the cause of death was bromadiolone poisoning. We suggest that professional monitoring is needed to assess the impact of rodenticides on Red Kites in areas where voles are controlled.
splm is an R package for the estimation and testing of various spatial panel data specifications. We consider the implementation of both maximum likelihood and generalized moments estimators in the context of fixed as well as random effects spatial panel data models. This paper is a general description of splm and all functionalities are illustrated using a well-known example taken from Munnell (1990) with productivity data on 48 US states observed over 17 years. We perform comparisons with other available software; and, when this is not possible, Monte Carlo results support our original implementation.