European Journal of Wildlife Research最新文献

Monitoring the body condition of feral horses is important for animal welfare considerations and to anticipate population densities that affect the ecosystem. Monthly adult body condition scores (BCS) were estimated in a population of feral horses in an Argentine grassland nature reserve in 2001 and 2002, when the population reached maximum historical density approaching estimated carrying capacity. Monthly mean BCS showed a seasonal pattern. Female BCS was higher throughout 2001 with respect to 2002, while males only showed this pattern between wet seasons. BCS was higher for males than for females throughout the study and also higher during the wet season for both sexes. Mean monthly BCS of males was correlated to precipitation of the previous month, which is known to determine grass productivity in the area. Lower BCS values for females can be explained by the additional energy expenditure associated with pregnancy and lactation. In many cases, continuous monitoring of body condition is not possible and then it is important to identify times of the year when it is a more sensitive indicator of the population’s proximity to carrying capacity. For the area, this would be during the peak of rainfall in autumn or the minimum of rainfall in winter. The estimates corresponding to females would be especially accurate considering their dependence to density and rainfall. The implementation of management measures guided by BCS could avoid reaching population levels close to carrying capacity, reducing the negative impacts on the environment and on the welfare of the horses themselves.

The Swedish wild boar (Sus scrofa) population has increased rapidly over the last decades, resulting in conflicts with human activities. Particularly, the increase has been challenging for agriculture as wild boar cause damage on crops and grasslands. To predict under what conditions to expect damage and where to prioritize management actions, basic knowledge about wild boar habitat and space use is needed. In this study, we used data from 99 wild boar equipped with GPS-collars, collected over a large temporal scale and throughout their distributional range in southern Sweden. We investigated wild boar home range size and habitat use across gradients of habitat availability and population density. Functional response in habitat use was assessed by estimating the use and availability of agricultural land on individual level and then, on population-level evaluating how use changed with changing availability. Finally, a potential response in habitat use was evaluated in relation to population density, i.e., the interaction between availability and population density. Home range size was negatively related to population density for both male and female wild boar. Wild boar used agricultural land more intensively with increasing population density and when other habitat types were less available. Our findings show that wild boar spatial behavior is highly context dependent and may vary considerably due to landscape characteristics and local conditions. Wild boars tend to overuse agricultural land at high densities which has strong implications for wildlife management. It is therefore important to consider local conditions when predicting space and habitat use by wild boar. Overall, this study provided a better understanding of the drivers of wild boar distribution and space use in agro-forested mosaic landscapes and how this knowledge can improve management practices.

Decreases in the diversity of farmland communities reported at various scales and across taxonomic groups have fueled searches for ultimate reasons, primarily focusing on aspects of agricultural land use. However, the importance of individual external factors as drivers of population dynamics may vary across populations. We used density estimates of the European hare (Lepus europaeus) from a study site near Czempiń, western Poland, covering a time series of 50 years, to analyse long-term trends in overwinter survival. We employed an autoregressive population model to test associations between cereals yields (as a proxy for agricultural land use), fox predation, winter climate and hare density, and compared our results to those reported for a Danish population exposed to an oceanic climate and a Czech population exposed to a more continental climate. We found that at the Polish study site, hare density was negatively associated with fox density, but there were no associations with cereals yield or winter climate. Using generalized additive models, we found nonlinear trends in autumn and spring hare densities also showing a gradual increase in overwinter survival from the 1970s to 2009. We did not detect any decreased juvenile productivity over the study period. We conclude that survival during the breeding season was the most significant demographic trait driving hare dynamics. Our study provides evidence of strong spatial variability in the importance of individual extrinsic factors as drivers of hare population trends.

Small mammals are potential bio-indicators of various ecosystems and their populations are often studied. However, many small mammal species are difficult to detect due to their small size and elusive behaviour. Camera trapping and live trapping are commonly employed survey techniques, but they both have their limitations. Recently developed techniques such as adjusted short-focal camera trapping and environmental DNA (eDNA) are promising new approaches, but their relative performance remains poorly quantified. We compared the effectiveness of three survey protocols for detecting a semi-aquatic and elusive small mammal, the Eurasian water shrew (Neomys fodiens), by (1) short-focal camera trapping, (2) live trapping, and (3) soil eDNA. During September and October 2022, we surveyed 20 transects of each 100 m in length alongside the Kleine Dommel, a lowland brook in the Netherlands. The effectiveness of the three survey protocols was compared based on detection probabilities. Short-focal camera trapping yielded a significantly higher detection probability than the eDNA protocol. Detection probabilities between short-focal camera trapping and live trapping and, between the eDNA protocol and live trapping, were not significantly different. Short-focal camera trapping is an effective technique to survey Eurasian water shrews. Furthermore, this method detected additional species compared to live trapping and is non-invasive and less labour-intensive. Short-focal camera trapping showed a promising method for small mammal surveys in general and we recommend further evaluation of its applicability for other small mammal species.

Abstract

North America holds a considerable share of global wildlife trade as both an importer and exporter of live animals and their parts. Wildlife trade is embedded in Canada’s history dating back to the early fur traders, evolving to include multiple commodities such as the contemporary fur industry and the thriving pet trade of today. Considering recent reports of animals legally and illegally imported into Canada and the potential threats of wildlife trade studied elsewhere, wildlife trade may pose risks to Canada’s natural heritage, biodiversity, biosecurity, and animal welfare. To delineate research needs pertaining to wildlife trade in Canada, we conducted a review of the existing literature. Our review included a systematic search of peer-reviewed scientific articles and grey literature to identify research gaps and opportunities. The analysis of 160 coded sources demonstrates that the existing literature on wildlife trade in Canada is limited, with only five journal articles focused specifically on trade in the Canadian context. Most research with a focus on wildlife trade was international in scope but identified Canada as an import or export country with connections to both legal and illegal trade. Although articles on luxury products and pet trades were the most frequently cited, substantial gaps remain in our understanding of Canada’s role, particularly in the trade of live animals for pets. Our review underscores the need to enhance academic knowledge and policy tools to effectively identify and address trade issues concerning Canadian and non-native wildlife. Implementing a robust monitoring system in Canada is critical to achieving successful oversight, characterisation, and control of wildlife trade in Canada.

Tokay geckos are one of the most heavily traded species internationally, largely to supply demand for use in traditional Chinese medicine. Tokay geckos are largely sourced from the wild. While there is a legal trade, illegal collection from the wild as well as laundering through fraudulent captive-breeding operations is common. Very little is known of the status of this species in the wild, though it is understood to be in decline in some parts of its range. Hong Kong is an important destination for tokay geckos in trade, and here, we assessed the availability, reported origin, and monetary value of tokay geckos in Hong Kong’s retail market. We surveyed 150 shops and found 220 tokay gecko pairs in 37% of all shops. We estimate that on average 15,000 tokay geckos are offered for sale in Hong Kong on any given day. The mean price of a tokay gecko pair is USD12, and the total retail value of the tokay geckos observed approaches USD180,000. Tokay geckos for sale in Hong Kong are said to be sourced from mainland China, Vietnam, and Thailand, and not from Indonesia despite Indonesia being the world’s largest exporter of tokay geckos. However, recent seizures in Hong Kong were from Indonesia. Despite shop staff stating tokay geckos were from Vietnam, there are no such reports in the CITES Trade Database. Tokay geckos are clearly being obtained from a combination of legal and illegal sources, and therefore increased vigilance and further investigation is called for to prevent illegal trade.

Brucellosis is a neglected zoonotic disease with significant public health impacts. It is primarily associated with classic Brucella species in mammals, but recent research has shown atypical Brucella strains in various hosts, including reptiles. Despite the known physiological differences between reptiles and humans, the rise in invasive reptile populations and other factors make reptiles and the pathogens they carry a potential public health concern. This study collected 90 venomous snakes from different regions in Iran and examined their liver samples, buccal, and cloaca cavities for Brucella spp. The samples underwent bacteriological analysis and DNA extraction. PCR amplification of the Omp28 gene and IS711-based PCR were used for the molecular identification of Brucella species. Subsequently, the Omp28 gene sequences were determined, and a phylogenetic tree was created. Brucella abortus was detected in the liver tissue of two snake species, namely Pseudocerastes persicus and Vipera albicornuta, at a prevalence rate of 2.2%. This finding is exceptional, as it has not been previously documented in venomous snake populations in the wild. The study confirms the presence of Brucella spp. in venomous snakes, suggesting the potential for zoonotic transmission. This discovery raises questions about the evolutionary forces shaping Brucella populations in reptiles. Understanding the prevalence and impact of Brucella in snakes is essential for wildlife conservation and assessing zoonotic risks. Proper safety measures are crucial when handling reptiles that may carry Brucella. Further research is needed to fill knowledge gaps regarding Brucella in these snake species and its potential zoonotic implications.

Wildlife managers and livestock owners can choose from a multitude of interventions to prevent carnivore attacks on domestic animals, ranging from light and sound deterrents to fencing and lethal control. To guide management and make the best and most cost-effective choice of interventions, knowledge about where and when these measures are needed the most is important. By identifying spatiotemporal patterns of carnivore attacks, resources can be used more efficiently to prevent such attacks. We used a Swedish nationwide, long-term data set to identify inter- and intra-seasonal variation in probability, number, and severity (number of killed or injured per attack) of large carnivore attacks on sheep. Our results show that there are specific “times of trouble”, regarding the number of attacks from golden eagle (Aquila chrysaetos) in late spring, and from brown bears (Ursus arctos), lynx (Lynx lynx), and wolves (Canis lupus) in late summer. Additionally, for brown bears and wolves, the severity of attacks varied throughout the grazing season with a peak in the latter part of the summer. The results can be used for guidance of temporal prioritisation of preventive interventions to reduce the probability, number, and severity of large carnivore attacks on sheep.

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.

Biological invasions are a major threat to biodiversity and have particularly devastating impacts on island ecosystems. The New Caledonia archipelago is considered a biodiversity hotspot due to its diverse native flora. Javan rusa deer (Rusa timorensis) were introduced to New Caledonia in 1870 and the population consists of several hundred thousand individuals today. They directly threaten rare endemic species and affect the composition and structure of the vegetation. While a rusa deer management plan has identified ten priority areas for deer control operations, removing deer could be offset by the dispersal of animals back into the control areas. Here, we genotyped 628 rusa deer using 16 microsatellite markers to analyse the genetic structure of the animals in New Caledonia. We aimed to assess fine-scale genetic structure, to identify natural barriers to deer movement and to assess functional connectivity by optimising individual-based landscape resistance models. Our results suggested that rusa deer formed a single genetic population on the main New Caledonian island. The isolation-by-distance pattern suggested that female dispersal was limited, whereas males had larger dispersal distances. We assessed functional connectivity using different genetic distance metrics and all models performed poorly (mR² ≤ 0.0043). Landscape features thus hardly affected deer movement. The characteristics of our results suggested that they were not an artefact of the colonisation history of the species. Achieving an effective reduction of deer population sizes in specific management areas will be difficult because of the deer’s high dispersal capabilities and impossible without very substantial financial investment.