Fox Density Research Articles

Density, abundance, and activity of the chilla or grey fox (Lycalopex griseus) in Isla Grande de Tierra del Fuego, Chile

BackgroundThe chilla or grey fox (Lycalopex griseus) is a native species from continental Chile and neighboring areas of Argentina. It was introduced to Isla Grande de Tierra del Fuego in 1951 and began to increase its abundance, to the chagrin of local sheep ranchers. Since 1998, its hunting has been authorized. Here we update information on the density, abundance, and activity of this fox in the Chilean sector of Tierra del Fuego Island, to evaluate its population trend since the last census conducted by the Servicio Agrícola y Ganadero (SAG) in 2007.Methods and resultsWe carried out two fox censuses on a 941-km transect on public roads, divided into eight routes, from October to November (spring) of 2021 and 2022, following the same design used by SAG for the fox assessments carried out from 1999 to 2007. We report a reduction of > 50% in the density and abundance of chilla foxes with respect to the 2007 estimate, which could be attributed to the interference by free-ranging dogs (Canis lupus familiaris), through restricting the use of space by the fox, while transmitting diseases and parasites, and to human hunting pressure and vehicle collisions.DiscussionThe chilla fox decline highlights the need for an in-depth study to determine the ecological and socioeconomic impact of this exotic species on the ecosystems of Tierra del Fuego Island and the desirability of its management, if needed.

Movement ecology and minimum density estimates of red foxes in wet grassland habitats used by breeding wading birds

The red fox (Vulpes vulpes) is a widely distributed generalist meso-predator implicated in declines of wading bird populations. In the wet grassland habitats where waders breed, wildlife managers work to mitigate fox predation risk to waders during the nesting period through lethal and non-lethal control methods. However, limited knowledge on fox movement ecology in these habitats makes it difficult to design effective management strategies. We used GPS telemetry to understand fox home range size, daily activity and movement patterns, and how these metrics may vary among wet grassland sites with different management. We caught and GPS-tagged 35 foxes in the March–June wader nesting period on two wet grassland sites in central southern England; Britford during 2016/17 and Somerley during 2018/19. We estimated home range areas from location data using local convex hulls, and from these estimates we derived the minimum fox density at each site and year. Daily activity patterns and movement behaviour of each fox were obtained using both telemetry and trail camera data. Mean fox home range area at Britford (0.21 km2, SE = 0.025) was significantly smaller than at Somerley (0.68 km2, SE = 0.067), and estimated minimum densities were around four times higher (Britford = 10.6 foxes/km2, Somerley = 2.4 foxes/km2). Foxes were more active and moved faster during twilight and night hours, but both telemetry and camera data indicate they were also active for one-third of daylight hours. Distances moved per day were variable between foxes but generally smaller at Britford. We also found evidence for dispersal during spring, with movements of up to 19 km per day. Home ranges at both wet grassland sites were smaller than comparable sites elsewhere. These indicated foxes were living at exceptionally high densities at Britford, where there is no fox control, increased food availability and where waders no longer breed. Spatio-temporal movement patterns were closely related to home range metrics, with higher levels of fox activity at Somerley, where home ranges were larger. The movements of itinerant and dispersing foxes during the nesting period suggests that lethal control would need to be very intensive to be effective. The likely anthropogenic food subsidy of fox density at Britford suggests that controlling access to similar food resources would help reduce predation pressure on breeding waders.

Effects of landcover on mesocarnivore density and detection rate along an urban to rural gradient

Human development has major implications for wildlife populations. Urban-exploiter species can benefit from human subsidized resources, whereas urban-avoider species can vanish from wildlife communities in highly developed areas. Therefore, understanding how the density of different species varies in response to landcover changes associated with human development can provide important insight into how wildlife communities are likely to change and provide a starting point for predicting the consequences of those changes. Here, we estimated the population density of five common mesocarnivore species (coyote (Canis latrans), bobcat (Lynx rufus), red fox (Vulpes vulpes), raccoon (Procyon lotor), and Virginia opossum (Didelphis virginiana)) at 12 study sites along an urban to rural gradient in the greater Fayetteville Area, Northwest Arkansas, USA between November 2021, and March 2022. At each study site, we applied the Random Encounter Model (REM) to data from camera traps to calculate the density of five focal species. Coyote density ranged from 0.5 to 0.93 individuals/km2. Raccoon density ranged from 0.19 to 20.25 individuals/km2. Bobcat density ranged from 0 to 1.06 individuals/km2. Opossum density ranged from 0 to 3.43 individuals/km2. Red fox density ranged from 0 to 0.10 individuals/km2. Coyote and raccoon density showed a positive relationship with anthropogenic noise. Opossum density increased with HUD. Red Fox and bobcat density showed a negative relationship with forest area and a positive relationship with distance to water respectively, however confidence intervals for both species overlapped zero. The density estimates we report based on camera trap data of unmarked animals were consistent with reports from the literature for these same species derived from traditional methods, providing additional support to the REM as a viable, non-invasive method to calculate density of unmarked species. Our second analysis consisted of taking camera level density estimates and treating them as detection rates corrected for camera viewshed and animal movement. Coyote and raccoon detection rate showed a positive relationship with anthropogenic noise. Red Fox detection rate was positively related to developed open space, and negatively related to distance to water. Similarly to red fox, opossums detection rate was higher in areas with more developed open space. We found no evidence that bobcat density or detection rate varied with any of the landcover or anthropogenic variables we measured.

Predator-mediated interactions through changes in predator home range size can lead to local prey exclusion.

The strength of indirect biotic interactions is difficult to quantify in the wild and can alter community composition. To investigate whether the presence of a prey species affects the population growth rate of another prey species, we quantified predator-mediated interaction strength using a multi-prey mechanistic model of predation and a population matrix model. Models were parametrized using behavioural, demographic and experimental data from a vertebrate community that includes the arctic fox (Vulpes lagopus), a predator feeding on lemmings and eggs of various species such as sandpipers and geese. We show that the positive effects of the goose colony on sandpiper nesting success (due to reduction of search time for sandpiper nests) were outweighed by the negative effect of an increase in fox density. The fox numerical response was driven by changes in home range size. As a result, the net interaction from the presence of geese was negative and could lead to local exclusion of sandpipers. Our study provides a rare empirically based model that integrates mechanistic multi-species functional responses and behavioural processes underlying the predator numerical response. This is an important step forward in our ability to quantify the consequences of predation for community structure and dynamics.

An Ongoing Shift in Mammalian Nest Predators of Yellow-billed Loons in Arctic Alaska

The Coastal Plain of northern Alaska is an important nesting area for a variety of avian species, where the productivity of ground-nesting species can be strongly influenced by nest predators. Recently, the density of red foxes (Vulpes vulpes) has increased in many areas of the Arctic, likely because of climate warming as well as the availability of anthropogenic food sources during winter. In areas where they occur sympatrically, red foxes can outcompete and kill the smaller Arctic fox (Vulpes lagopus). There is considerable dietary overlap between the fox species, but if the red fox is a more successful nest predator, this ongoing shift in canid species could have important implications for ground-nesting species like the Yellow-billed Loon (Gavia adamsii). We examined time-lapse photographs from 186 nests of Yellow-billed Loons in northern Alaska during the years 2008 – 15 and 2019 for the presence of foxes and other nest predators and quantified nest predation by species. Although both Arctic and red foxes were photographed near nests, we found that all successful predation of Yellow-billed Loon nests by foxes was attributable to red foxes, which were the second most frequent predator of Yellow-billed Loon nests after Glaucous Gulls (Larus hyperboreus). Arctic foxes photographed at Yellow-billed Loon nests were unsuccessful at displacing incubating loons. Several data sources suggest that the prevalence of red foxes has increased in Arctic Alaska over the last three decades, a change that is likely to have negative impacts on the nesting success of Yellow-billed Loons and possibly other large waterbirds.

Fifty years of spring censuses in black grouse (Lyrurus tetrix) in the High Fens (Belgium): did the rabies vaccination has a negative impact on a fox prey population?

The online version contains supplementary material available at 10.1007/s10344-023-01642-w.

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

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

Pampas fox spatial and temporal variation in Argentinean agroecosystems

Context Agricultural activities have reduced wildlife natural habitats and increased the spatial overlap between animals’ distribution and human activities. However, carnivores with a broad diet and flexible habitat requirements can tolerate human-induced environmental changes. Thus, identifying changes in their densities and spatial distribution are important factors to take into consideration when working towards minimising human–carnivore conflict. Aims Our aim was to identify the main environmental and human variables influencing Pampas fox density and to produce density maps in the reproductive and non-reproductive seasons. Methods We performed spotlight counts at night, following the line transect method in the non-reproductive and reproductive seasons during two consecutive years. We also obtained landscape, human-impact and environmental spatial variables using remote sensing data and Geographic Information Systems. We modelled and mapped the Pampas fox’s spatial density using Density Surface Models. Key results We found that disturbance by human activities and landscape configuration influenced the spatial variation of the Pampas fox density across time and space. We registered a positive association between the number of foxes and the proximity to urban areas and paved roads, and we also found higher densities near grasslands areas and less modified habitats varying with the season and year. A higher density of foxes was observed in the non-reproductive season compared with the reproductive season. Conclusions and Implications This study provides insight on the variation in Pampas fox densities across agroecosystems. It highlights the relevance of more naturalised and protected habitats to sustain the Pampas fox population in highly fragmented landscapes, but also shows a positive association with disturbed areas. The spatial information developed in this study is useful to identify areas where ecosystem services could be encouraged, helping to maintain the ecosystems’ equilibrium and biodiversity conservation, and develop new management programs creating human–wildlife coexistence.

Assessing Red Fox (Vulpes vulpes) Demographics to Monitor Wildlife Diseases: A Spotlight on Echinococcus multilocularis

The assessment of red fox population density is considered relevant to the surveillance of zoonotic agents vectored by this species. However, density is difficult to estimate reliably, since the ecological plasticity and elusive behavior of this carnivore hinder classic methods of inference. In this study, red fox population density was estimated using a non-invasive molecular spatial capture-recapture (SCR) approach in two study areas: one in a known hotspot of the zoonotic cestode Echinococcus multilocularis, and another naïve to the parasite. Parasitological investigations on collected samples confirmed the presence of the parasite exclusively in the former area; the SCR results indicated a higher fox population density in the control area than in the hotspot, suggesting either that the relationship between fox density and parasite prevalence is not linear and/or the existence of other latent factors supporting the parasitic cycle in the known focus. In addition, fox spotlight count data for the two study areas were used to estimate the index of kilometric abundance (IKA). Although this method is cheaper and less time-consuming than SCR, IKA values were the highest in the areas with the lower molecular SCR density estimates, confirming that IKA should be regarded as a relative index only.

An Ongoing Shift in Mammalian Nest Predators of Yellow-billed Loons in Arctic Alaska


 The Coastal Plain of northern Alaska is an important nesting area for a variety of avian species, where the productivity of ground-nesting species can be strongly influenced by nest predators. Recently, the density of red foxes (Vulpes vulpes) has increased in many areas of the Arctic, likely because of climate warming as well as the availability of anthropogenic food sources during winter. In areas where they occur sympatrically, red foxes can outcompete and kill the smaller Arctic fox (Vulpes lagopus). There is considerable dietary overlap between the fox species, but if the red fox is a more successful nest predator, this ongoing shift in canid species could have important implications for ground-nesting species like the Yellow-billed Loon (Gavia adamsii). We examined time-lapse photographs from 186 nests of Yellow-billed Loons in northern Alaska during the years 2008 – 15 and 2019 for the presence of foxes and other nest predators and quantified nest predation by species. Although both Arctic and red foxes were photographed near nests, we found that all successful predation of Yellow-billed Loon nests by foxes was attributable to red foxes, which were the second most frequent predator of Yellow-billed Loon nests after Glaucous Gulls (Larus hyperboreus). Arctic foxes photographed at Yellow-billed Loon nests were unsuccessful at displacing incubating loons. Several data sources suggest that the prevalence of red foxes has increased in Arctic Alaska over the last three decades, a change that is likely to have negative impacts on the nesting success of Yellow-billed Loons and possibly other large waterbirds.

RABIES IN ARCTIC FOX (VULPES LAGOPUS) AND REINDEER (RANGIFER TARANDUS PLATYRHYNCHUS) DURING AN OUTBREAK ON SVALBARD, NORWAY, 2011–12

Rabies is an important zoonotic disease with high fatality rates in animals and humans. In the Arctic, the Arctic fox (Vulpes lagopus) is regarded as the principal reservoir, but there is considerable debate about how the disease persists at the low population densities that are typical for this species. We describe an outbreak of rabies among Arctic foxes and Svalbard reindeer (Rangifer tarandus platyrhynchus) during 2011-12 on the remote Arctic archipelago of Svalbard, an area with a very low and relatively stable Arctic fox density. The aim of the research was to increase knowledge of Arctic rabies in this ecosystem and in the presumed spillover host, the Svalbard reindeer. Phylogenetic analysis of rabies virus (RABV) RNA isolates from Arctic fox and reindeer was performed, and clinical observations and histologic and immunohistochemical findings in reindeer were described. An ongoing capture-mark-recapture project allowed collection of serum samples from clinically healthy reindeer from the affected population for detection of rabies virus-neutralizing antibodies. The outbreak was caused by at least two different variants belonging to the RABV Arctic-2 and Arctic-3 clades, which suggests that rabies was introduced to Svalbard on at least two different occasions. The RABV variants found in Arctic fox and reindeer were similar within locations, suggesting that Arctic foxes and reindeer acquired the infection from the same source(s). The histopathologic and immunohistochemical findings in 10 reindeer were consistent with descriptions in other species infected with RABV of non-Arctic lineages. Evidence of RABV was detected in both brain and salivary gland samples. None of 158 examined serum samples from clinically healthy reindeer had virus-neutralizing antibodies against RABV.

Genetic sampling and an activity index indicate contrasting outcomes of lethal control for an invasive predator

ABSTRACTInvasive mammalian predators are implicated in the ongoing decline of a suite of fauna and continue to be a major cause of human–wildlife conflict globally. Lethal control of invasive predators is a common management strategy; however, the use of activity indices to measure management effectiveness is problematic. Non‐invasive genetic sampling may be a viable alternative approach to monitoring as individual animals can be identified, allowing for direct estimation of population density through newly developed spatially explicit capture–recapture techniques. Here we compare inferences derived from a basic activity index (number of scats per survey) and genetic sampling of scats within a before–after control–impact design to evaluate the effectiveness of a lethal control programme targeting red foxes (Vulpes vulpes) in south‐eastern Australia. The activity index was highly variable through time and suggested the baiting programme reduced fox activity on the treatment transect relative to changes on the non‐treatment transect. In contrast, genetic sampling and spatially explicit capture–recapture analysis suggested fox density varied little throughout the study, with any changes unable to be attributed to the baiting programme. Additionally, genetic sampling confirmed many individuals persisted through 7 months of baiting. These contrasting results may be partially explained by changes in scat detectability due to seasonal changes in behaviour and the disproportionate contribution of some individuals to scat counts. Our pre‐baiting density estimate of 0.28 foxes km2 (95% CI: 0.22–0.38) was lower than expected given the high productivity, abundant prey species and lack of larger predators in the study region. Our results highlight the need for cautious interpretation of activity indices and demonstrates the value of incorporating recent methodological and statistical advances when evaluating lethal control programmes.

Counting the bodies: Estimating the numbers and spatial variation of Australian reptiles, birds and mammals killed by two invasive mesopredators

AbstractAimIntroduced predators negatively impact biodiversity globally, with insular fauna often most severely affected. Here, we assess spatial variation in the number of terrestrial vertebrates (excluding amphibians) killed by two mammalian mesopredators introduced to Australia, the red fox (Vulpes vulpes) and feral cat (Felis catus). We aim to identify prey groups that suffer especially high rates of predation, and regions where losses to foxes and/or cats are most substantial.LocationAustralia.MethodsWe draw information on the spatial variation in tallies of reptiles, birds and mammals killed by cats in Australia from published studies. We derive tallies for fox predation by (i) modelling continental‐scale spatial variation in fox density, (ii) modelling spatial variation in the frequency of occurrence of prey groups in fox diet, (iii) analysing the number of prey individuals within dietary samples and (iv) discounting animals taken as carrion. We derive point estimates of the numbers of individuals killed annually by foxes and by cats and map spatial variation in these tallies.ResultsFoxes kill more reptiles, birds and mammals (peaking at 1071 km−2 year−1) than cats (55 km−2 year−1) across most of the unmodified temperate and forested areas of mainland Australia, reflecting the generally higher density of foxes than cats in these environments. However, across most of the continent – mainly the arid central and tropical northern regions (and on most Australian islands) – cats kill more animals than foxes. We estimate that foxes and cats together kill 697 million reptiles annually in Australia, 510 million birds and 1435 million mammals.Main conclusionsThis continental‐scale analysis demonstrates that predation by two introduced species takes a substantial and ongoing toll on Australian reptiles, birds and mammals. Continuing population declines and potential extinctions of some of these species threatens to further compound Australia's poor contemporary conservation record.

Red foxes at their northern edge: competition with the Arctic fox and winter movements

Abstract Rapid range expansion of boreal forest predators onto the tundra may disrupt local ecological processes, notably through competition with ecologically similar species. Red foxes (Vulpes vulpes) have expanded their range northwards throughout the Canadian Arctic, inducing competition with endemic Arctic foxes (V. lagopus). We studied competition between Arctic and red foxes, with a focus on interference competition, and winter movements of red foxes using satellite telemetry and den occupancy data from both species. We worked at Bylot Island (Nunavut) and Herschel Island (northern Yukon), two sites at the northern limit of the red fox’s range. As expected, red fox home ranges were 56% larger on average than Arctic fox home ranges. However, red foxes did not exclude Arctic foxes regionally nor did they prevent them from breeding successfully in their vicinity. On Bylot Island, Arctic foxes did not spatially avoid red foxes more than their conspecifics, as evidenced by similar intra- and interspecific home-range overlaps. On Herschel Island, the red fox pair’s home range extensively overlapped the home range of their Arctic fox neighbors. While red foxes tracked on Bylot Island survived several winters without expanding or leaving their home ranges, those on Herschel Island moved onto the sea ice and died. Overall, our results demonstrate low levels of interference competition between the two species in the High Canadian Arctic. When red fox density is low, as in our study areas where land protection prevents predator subsidization by anthropogenic food sources, Arctic and red foxes may be able to co-exist with limited antagonistic interactions. Our sample sizes were limited by the naturally low density of red foxes at their northernmost edge. Replication therefore is needed to fully understand winter space use and intraguild interactions in this species at its northern range limit.

Mixed‐severity wildfire and salvage logging affect the populations of a forest‐dependent carnivoran and a competitor

AbstractEffects of historical fire suppression in forested ecosystems, combined with increasingly frequent and prolonged periods of drought due to a changing climate, are predicted to drive increases in the extent and intensity of wildfires in western North America and elsewhere. Understanding the effects of wildfires on forest‐dependent species and interactions among species is important for conservation and management decisions. We used data collected from a long‐term carnivore monitoring program in northern California and southern Oregon, USA to investigate the effects of three mixed‐severity wildfires and salvage logging on a population of fishers (Pekania pennanti), forest‐dependent carnivoran of conservation concern, and a co‐occurring population of gray foxes (Urocyon cinereoargenteus), a competitor of similar body size. We developed a spatial capture‐recapture population model to estimate the short‐term effects of the wildfires and salvage logging on fisher and gray fox abundances, distributions, apparent survival and recruitment, and species interactions using non‐invasive genetic data collected three years prior to and three years following wildfires. Fisher abundance decreased significantly in areas of low‐, medium‐, and high‐severity wildfire. Gray fox abundance decreased in the years before the wildfires, but rebounded in subsequent years. Medium‐severity wildfire had a negative effect on gray fox density, but high‐severity wildfire and fisher density had positive effects on gray fox density. Salvage logging had negative effects on both fisher and gray fox density. Our results suggest that increased severity, extent, and frequency of wildfires in the western USA will affect fisher populations negatively and alter the composition of mesocarnivoran communities.

A comparison of methods for monitoring a sparse population of the red fox (Vulpes vulpes) subject to lethal control using GPS telemetry, camera traps and sand plots

Context The introduced red fox has driven the decline or extinction of numerous wildlife species in Australia, yet little information exists on the population densities of foxes in most ecosystems. Fox monitoring programs will differ widely depending on the goals of management, which, in turn, will determine whether the appropriate metric is a density estimate, or some proxy thereof, and the time and resources required. Aims This study aims to assist wildlife managers to design fit-for-purpose monitoring programs for foxes by providing a better understanding of the utility and precision of various monitoring methods. Methods We surveyed foxes monthly over four consecutive years in a semi-arid region of Australia by using sand plots, camera traps and GPS telemetry. The resultant data were used to produce population estimates from one count-based method, two spatially explicit methods, and two activity indices. Key results The incorporation of GPS-collar data into the spatial capture–recapture approaches greatly reduced uncertainty in estimates of abundance. Activity indices from sand plots were generally higher and more variable than were indices derived from camera traps, whereas estimates from N-mixture models appeared to be biased high. Conclusions Our study indicated that the Allen–Engeman index derived from camera-trap data provided an accurate reflection of change in the underlying fox density, even as density declined towards zero following introduction of lethal control. This method provides an efficient means to detect large shifts in abundance, whether up or down, which may trigger a change to more laborious, but precise, population monitoring methods. If accuracy is paramount (e.g. for reintroduction programs) spatially explicit methods augmented with GPS data provide robust estimates, albeit at a greater cost in resources and expertise than does an index. Implications Our study demonstrated that the shorter the survey period is, the greater is the likelihood that foxes are present but not detected. As such, if limited resources are available, longer monitoring periods conducted less frequently will provide a more accurate reflection of the underlying fox population than do shorter monitoring periods conducted more often.

Estimating red fox density using non-invasive genetic sampling and spatial capture\u2013recapture modelling

Spatial capture–recapture modelling (SCR) is a powerful tool for estimating density, population size, and space use of elusive animals. Here, we applied SCR modelling to non-invasive genetic sampling (NGS) data to estimate red fox (Vulpes vulpes) densities in two areas of boreal forest in central (2016–2018) and southern Norway (2017–2018). Estimated densities were overall lower in the central study area (mean = 0.04 foxes per km2 in 2016, 0.10 in 2017, and 0.06 in 2018) compared to the southern study area (0.16 in 2017 and 0.09 in 2018). We found a positive effect of forest cover on density in the central, but not the southern study area. The absence of an effect in the southern area may reflect a paucity of evidence caused by low variation in forest cover. Estimated mean home-range size in the central study area was 45 km2 [95%CI 34–60] for females and 88 km2 [69–113] for males. Mean home-range sizes were smaller in the southern study area (26 km2 [16–42] for females and 56 km2 [35–91] for males). In both study areas, detection probability was session-dependent and affected by sampling effort. This study highlights how SCR modelling in combination with NGS can be used to efficiently monitor red fox populations, and simultaneously incorporate ecological factors and estimate their effects on population density and space use.

Scabies in wildlife animals, pets and humans: a re-emerging zoonosis?

Abstract Background Scabies or sarcoptic mange is an infestation of the skin caused by the mite Sarcoptes scabiei. Transmission from animals to humans occurs through close contact. The most common symptoms are papules, erythema, excoriations, hyperkeratosis, and hypotrichosis. In the province of Ferrara (Emilia Romagna, Italy) mange is endemic in wild animals, mostly in foxes, which can act as vectors for domestic animals and humans. Methods From 2012 to 2020, 564 foxes were surveyed within the Wildlife Health Surveillance Re-gional Program, including microscopic examination in cases of skin lesions referable to scabies. In 2018, a domestic dog (10-year border collie, male), frequenting an uncultivated area colonized by foxes and located in the outskirts of Ferrara, showed scabby lesions mainly on the nose, around the eyes and on the back. Results 11 out of 564 foxes resulted positive (1,95%), 6 cases out of 38 being in 2018 (15,8%). The parasite was detected by skin biopsy and direct microscopic examination in the domestic dog. The parasite was transmitted by the dog to the owner and the other two family members. Conclusions The increased density of dogs and foxes in the Ferrara province, and the attitude of foxes to live near to human settlements, increase the risk of contacts between foxes, domestic animals and humans, even though stray dogs are uncommon. This case illustrates the interdependencies between animal health, human health and environment, a synergy that can enable exacerbation of diseases of zoonotic origin as highlighted by the One Health concept. It is therefore important to increase the investigation on paths as well as vectors of diseases and to find collaborative, multi-sectorial and transversal approaches to ensure quality health outcomes. The control of the disease requires an appropriate monitoring of dogs' health being skin lesions in both, humans and animals, very similar to allergic dermatitis, which can delay the proper diagnosis of the disease. Key messages Sarcoptic mange is a zoonosis still present in Emilia Romagna, Italy. The One Health approach is key to control the cycle of the zoonotic sarcoptic mange.

История борьбы с бешенством в Украине со времен Пастера до наших дней

Бешенство остается древнейшим вирусным зоонозным заболеванием, которое всегда заканчивается летально и которое в наши дни широко распространено по всему миру и ежегодно вызывает смерть около 60 тысяч человек. Поскольку борьба с ликвидацией гидрофобии в Украине ведется уже более 135 лет, нашей целью было напомнить о проблемах и успехах оказания антирабической помощи в разные периоды эпизоотического процесса в прошлом веке, напомнить основные специфические особенности заражения и показать реальные проблемы в наши дни. Материалами для анализа были архивные данные из сводных отчетов областных СЭС, Института эпидемиологии и инфекционных заболеваний имени Л.В. Громашевского, лаборатории нейроинфекций ИВМ НААН Украины, а также отчеты областных администраций ветеринарной медицины Госпродпотребслужбы Украины. Было показано, что пики эпизоотий наблюдались в определенные исторические периоды. Во время первого периода, городского бешенства (собак), свою эффективность показали массовые вакцинации собак в комплексе с жесткой регуляцией численности бездомных животных. Второй период, связанный с лисьим бешенством, продолжался 30 лет, из которых почти 20 лет были относительно благополучными, чему способствовало строжайшее соблюдение во всех областях Украины мер по регуляции численности лисиц. В начале XXI века резко повысилась напряженность эпизоотического процесса. При этом во всех областях численность лисиц уже не поддерживалась на безопасном уровне, и их заболеваемость увеличилась почти в 20 раз. Начатая в 2001 году пероральная вакцинация до настоящего времени проводится не в полном объеме. Вакцинация домашних плотоядных животных также не достигает необходимого уровня покрытия 70 % популяции. Пытаются прививать и бездомных животных, хотя уже давно доказано, что в период постоянных стрессов и переохлаждения вакцина не вызывает выработку иммунитета до защитного уровня. Таким образом, в настоящее время главную проблему при обращении за антирабической помощью составляют собаки. Так, в 2019 году за помощью по поводу укуса собакой обратились 51 232 человека. В целом в 2019 году за антирабической помощью обратились 73 962 человека, прививки были назначены 21 980 лицам. С тяжелыми укусами отмечалось 4039 человек, из них 1161 человек были укушены больным животным с подтвержденным диагнозом и 777 человек были укушены дикими животными (то есть 1938 человек были спасены от смерти), а 16 113 лицам, получившим легкие укусы (73,3 % от числа привитых), было дано 10 дней для выяснения опасности укуса, но сделать это не удалось, так как укусившее животное убежало. За счет этой категории пострадавших количество привитых резко увеличивается. Важно отметить, что каждый укус бродячей собакой для пострадавшего — испытание, а курс антирабических прививок стоит около 6 тыс. грн в зависимости от тяжести укуса, поэтому открытым остается вопрос о регуляции численности бездомных собак и целесообразности их вакцинации.

Atto-Foxes and Other Minutiae

This paper addresses the problem of extinction in continuous models of population dynamics associated with small numbers of individuals. We begin with an extended discussion of extinction in the particular case of a stochastic logistic model, and how it relates to the corresponding continuous model. Two examples of ‘small number dynamics’ are then considered. The first is what Mollison calls the ‘atto-fox’ problem (in a model of fox rabies), referring to the problematic theoretical occurrence of a predicted rabid fox density of 10^{-18} (atto-) per square kilometre. The second is how the production of large numbers of eggs by an individual can reliably lead to the eventual survival of a handful of adults, as it would seem that extinction then becomes a likely possibility. We describe the occurrence of the atto-fox problem in other contexts, such as the microbial ‘yocto-cell’ problem, and we suggest that the modelling resolution is to allow for the existence of a reservoir for the extinctively challenged individuals. This is functionally similar to the concept of a ‘refuge’ in predator–prey systems and represents a state for the individuals in which they are immune from destruction. For what I call the ‘frogspawn’ problem, where only a few individuals survive to adulthood from a large number of eggs, we provide a simple explanation based on a Holling type 3 response and elaborate it by means of a suitable nonlinear age-structured model.