Large impact of Eurasian lynx predation on roe deer population dynamics

Molecular analysis of scats revealed diet and prey choice of grey wolves and Eurasian lynx in the contact zone between the Dinaric Mountains and the Alps

A comprehensive understanding of the dietary habits of carnivores is essential to get ecological insights into their role in the ecosystem, potential competition with other carnivorous species, and their effect on prey populations. Genetic analysis of non-invasive samples, such as scats, can supplement behavioural or microscopic diet investigations. The objective of this study was to employ DNA metabarcoding to accurately determine the prey species in grey wolf (Canis lupus) and Eurasian lynx (Lynx lynx) scat samples collected in the Julian Alps and the Dinaric Mountains, Slovenia. The primary prey of wolves were red deer (Cervus elaphus) (detected in 96% scat samples), European roe deer (Capreolus capreolus) (68%), and wild boar (Sus scrofa) (45%). A smaller portion of their diet consisted of mesocarnivores, small mammals, and domestic animals. In contrast, the lynx diet mostly consisted of European roe deer (82%) and red deer (64%). However, small mammals and domestic animals were also present in lynx diet, albeit to a lesser extent. Our findings indicate that the dietary habits of wolves and lynx are influenced by geographical location. Snapshot dietary analyses using metabarcoding are valuable for comprehending the behaviour and ecology of predators, and for devising conservation measures aimed at sustainable management of both their natural habitats and prey populations. However, to gain a more detailed understanding of wolf and lynx dietary habits and ecological impact, it would be essential to conduct long-term genetic monitoring of their diet.

Taenia lynciscapreoli in semi-domesticated reindeer (Rangifer tarandus tarandus, L.) in Sweden

We report here Taenia lynciscapreoli metacestode from the lung lobe of a semi-domesticated reindeer (Rangifer tarandus tarandus). The specimen was detected within a development project concerning remote post mortem inspection at a reindeer abattoir in Sweden. Post mortem inspection was performed according to a routine on-site official meat inspection protocol. The species identification to T. lynciscapreoli was confirmed based on the DNA extracted from the metacestode, which was analysed by sequencing of the cytochrome c oxidase subunit 1. Firstly, our finding shows that semi-domesticated reindeer in addition to several other cervids can act as an additional intermediate host for T. lynciscapreoli. Secondly, it further confirms that this parasite is more widely distributed on the Scandinavian peninsula than what has previously been shown. This is in line with a previous molecular finding of adult T. lynciscapreoli from the Eurasian lynx (Lynx lynx) in Sweden and demonstrates that new intermediate host can be detected. Whether the present finding can be regarded as accidental or have created opportunities for an expansion throughout the northernmost Scandinavian Peninsula remains to be seen.

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Semi-domesticated reindeer can act as the intermediate host for T. lynciscapreoli.

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T. lynciscapreoli is more widely distributed than previously shown.

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The impact on reindeer welfare remains unknown.

Kill rates and associated ecological factors for an apex predator

Kill rates and functional responses are fundamental to the study of predator ecology and the understanding of predatory-prey dynamics. As the most widely distributed apex predator in the western hemisphere, pumas (Puma concolor) have been well studied, yet a synthesis of their kill rates is currently lacking. We reviewed the literature and compiled data on sex- and age-specific kill rate estimates of pumas on ungulates, and conducted analyses aimed at understanding ecological factors explaining the observed spatial variation. Kill rate studies on pumas, while numerous, were primarily conducted in Temperate Conifer Forests (< 10% of puma range), revealing a dearth of knowledge across much of their range, especially from tropical and subtropical habitats. Across studies, kill rates in ungulates/week were highest for adult females with kitten(s) (1.24 ± 0.41 ungulates/week) but did not vary significantly between adult males (0.84 ± 0.18) and solitary adult females (0.99 ± 0.26). Kill rates in kg/day differed only marginally among reproductive classes. Kill rates of adult pumas increased with ungulate density, particularly for males. Ungulate species richness had a weak negative association with adult male kill rates. Neither scavenger richness, puma density, the proportion of non-ungulate prey in the diet, nor regional human population density had a significant effect on ungulate kill rates, but additional studies and standardization would provide further insights. Our results had a strong temperate-ecosystem bias highlighting the need for further research across the diverse biomes pumas occupy to fully interpret kill rates for the species. Data from more populations would also allow for multivariate analyses providing deeper inference into the ecological and behavioural factors driving kill rates and functional responses of pumas, and apex predators in general.

Long‐term changes in habitat selection and prey spectrum in a reintroduced Eurasian lynx ( Lynx lynx) population in Switzerland

When wild‐caught Eurasian lynx (Lynx lynx) from the Slovak Carpathian Mountains were reintroduced to Central Switzerland in the early 1970s and spread through the north‐western Swiss Alps (NWA), they faced a largely unfamiliar landscape with strongly fragmented forests, high elevations, and intense human land use. For more than 30 years, radio‐collared lynx have been monitored during three different project periods (in the 1980s, 1990s, and 2010s). Our study explored, how lynx over generations have learned to adjust to the alpine environment. We predicted that (1) lynx nowadays select more strongly for open habitats, higher elevations, and steep slopes compared to the early stages of recolonization and that (2) consequently, there were significant changes in the Eurasian lynx’ prey spectrum. To test our predictions, we analyzed telemetry data (VHF, GPS) of 13 adult resident lynx in the NWA over 35 years, using Resource Selection Functions. Furthermore, we compared kills recorded from different individuals inhabiting the same region during three project periods. In general, lynx preferred forested areas, but over the years, they avoided open habitat less. Compared to the early stage of the recolonization, lynx in the most recent project period selected for higher elevations and the proportion of chamois in their prey spectrum surmounted that of roe deer. Potential driving factors for the observed changes could be increasing tolerance to human presence, intraspecific competition, or fitness benefits through exploitation of new resources. Long‐term studies like ours provide important insight into how animals can respond to sudden environmental changes, e.g., in the course of translocations into new areas or anthropogenic alterations of their habitats.

Successful Deer Management in Scotland Requires Less Conflict Not More

What would successful deer management look like in Scotland? To some, flourishing populations of native wild deer represent success. But to others, negative impacts such as damage to woodlands and peatlands, agricultural and forestry losses, deer-vehicle collisions, and facilitating Lyme disease spread represent failure. Conflicting interests and incentives among people involved in deer management mean a common definition of success, and therefore clear management targets, remain elusive. While some environmental groups urgently call for an increase in the number of deer culled (shot) each year, other stakeholders aim to maximize deer numbers. Overcoming this governance failure will require clearly articulated, scientifically valid, and socially acceptable socio-ecological objectives to be co-produced by a broad range of stakeholders. Systematic monitoring of deer impacts will also be needed to evaluate the ability of specific management interventions to achieve defined objectives. Reintroducing Eurasian lynx (Lynx lynx) has been suggested as a means to reduce deer numbers and their negative ecological and socioeconomic impacts. However, evidence of lynx impacts on deer numbers, deer impacts, and social conflicts over deer suggest lynx reintroduction alone would not effectively reduce negative impacts of deer in Scotland, though it could be part of a broader solution. In the short-term, achieving sustainable numbers of deer in Scotland will require a substantial increase in the number of deer culled and effective changes to the way deer management is incentivized, regulated, implemented, and monitored.

Demography of a Eurasian lynx (Lynx lynx) population within a strictly protected area in Central Europe

Large carnivores promote crucial ecosystem processes but are increasingly threatened by human persecution and habitat destruction. Successful conservation of this guild requires information on long-term population dynamics obtained through demographic surveys. We used camera traps to monitor Eurasian lynx between 2009 and 2018 in a strictly protected area in the Bohemian Forest Ecosystem, located in the core of the distribution of the Bohemian-Bavarian-Austrian lynx population. Thereby, we estimated sex-specific demographic parameters using spatial capture-recapture (SCR) models. Over 48,677 trap nights, we detected 65 unique lynx individuals. Density increased from 0.69 to 1.33 and from 1.09 to 2.35 individuals/100 km2 for open and closed population SCR models, respectively, with corresponding positive population growth rates (mean = 1.06). Estimated yearly sex-specific survival probabilities for the entire monitoring period were high (females 82%, males 90%) and per capita recruitment rate was low (females 12%, males 9%), indicating a low yearly population turnover. We ascertained an average number of recruits of 1.97 and a generation time of 2.64 years when considering resident reproducing females. We confirmed that reproduction in the study area took place successfully every year. Despite the overall increase in local lynx densities, the number of detected family groups remained constant throughout the study period. These results indicated that the strictly protected study area acts as a source for the multi-use landscapes in its surroundings. In this first open population SCR study on lynx, we provide sex-specific demographic parameters that are fundamental information for lynx management in the study area as well as in similar contexts Europe-wide.

Behavioral effects of wolf presence on moose habitat selection: testing the landscape of fear hypothesis in an anthropogenic landscape

Landscape of fear refers to the spatial variation in prey perception of predation risk, that under certain conditions, may lead to changes in their behavior. Behavioral responses of prey in relation to large carnivore predation risk have mainly been conducted in areas with low anthropogenic impact. We used long-term data on the distribution of moose in different habitat types in a system characterized by intensive management of all three trophic levels (silviculture, harvest of wolves and moose) to study effects on moose habitat selection resulting from the return of an apex predator, the wolf. We assumed that coursing predators such as wolves will cause an increased risk for moose in some habitat types and tested the hypotheses that moose will avoid open or young forest habitats following wolf establishment. After wolf recolonization, moose reduced their use of one type of open habitat (bog) but there was neither change in the use of the other open habitat type (clear-cut), nor in their use of young forest. Wolf establishment did not influence the use of habitat close to dense habitat when being in open habitats. Thus, the effect of wolves varied among habitat types and there was no unidirectional support for a behavioral effect of wolves' establishment on moose habitat use. Human-driven habitat heterogeneity, concentration of moose forage to certain habitat types, and the effects of a multiple predator guild on moose may all contribute to the results found. We conclude that the landscape of fear is likely to have weak ecological effects on moose in this system.

There is only one winner: The negative impact of red deer density on roe deer numbers and distribution in the Słowiński National Park and its vicinity

Red and roe deer are the most numerous cervids in Europe, and they occur in sympatry in most regions. Roe deer were considered to be an inferior competitor in studies in which they co-occurred with fallow deer or muntjac. Despite the remarkable overlap of their ranges, there are few studies on the competition between the red and roe deer. Since interspecific interactions among ungulates are often related to their mutual densities, the current study focused on the effects of high red deer density on the roe deer numbers and spatial distribution in the unhunted Słowiński National Park (SNP) in northern Poland and forest districts open to hunting bordering the park. Using fecal pellet group counts, it was found that in the forest districts (where red deer densities were 2-3 times lower than in the SNP), roe deer densities were significantly higher than in the park. The red-to-roe deer density ratio was 10.8 and 2.7, in the SNP and the surrounding forest districts, respectively. Moreover, in the SNP, the roe deer distribution was negatively affected by the red deer habitat use, while in the hunting areas, such an effect was not recorded. The negative influence of the red deer on the roe deer population in the park was most probably due to the red deer impact on food availability. The biomass of the plant groups forming the staple food of the roe deer (Rubus spp., forbs, dwarf shrubs) was significantly higher in the fenced plots than in the unfenced ones. Lack of hunting in the protected areas may benefit only some species in ungulate assemblages which, in turn, may contradict one of their objectives-to maintain viable and ecologically functional populations.

Extreme home range sizes among Eurasian lynx at the northern edge of their biogeographic range

Eurasian lynx (Lynx lynx) have a wide distribution across Eurasia. The northern edge of this distribution is in Norway, where they reach up to 72 degrees north. We conducted a study of lynx space use in this region from 2007 to 2013 using GPS telemetry. The home range sizes averaged 2,606 (± 438 SE) km2 for males (n = 9 ranges) and 1,456 (± 179 SE) km2 for females (n = 24 ranges). These are the largest home ranges reported for any large felid, and indeed are only matched by polar bears, arctic living wolves, and grizzly bears among all the Carnivora. The habitat occupied was almost entirely treeless alpine tundra, with home ranges only containing from 20% to 25% of forest. These data have clear implications for the spatial planning of lynx management in the far north as the current management zones are located in unsuitable habitats and are not large enough to encompass individual lynx movements.

Extinction risk assessment of a Patagonian ungulate using population dynamics models under climate change scenarios

Climate change affects population cycles of several species, threatening biodiversity. However, there are few long-term studies on species with conservation issues and restricted distributions. Huemul is a deer endemic to the southern Andes in South America and it is considered endangered mostly due to a 50% reduction of its distribution over the last 500 years. To assess environmental variables potentially affecting huemul population viability and the impact of climate change, we developed population dynamics models. We used a 14-year survey data from Bernardo O'Higgins National Park, coastal Chilean Patagonia. We used Ricker models considering winter and spring temperatures and precipitation as variables influencing huemul population dynamics. We used the Bayesian information criterion (BIC) to select models with the greatest predictive power. The two best models (ΔBIC < 2) included winter temperature and density-dependence population growth drivers. The best model considered a lateral effect, where winter temperature influences carrying capacity and the second best a vertical effect with winter temperature influencing R_max and carrying capacity. Population viability was evaluated using those models, projecting them over a 100-year period: (a) under current conditions and (b) under conditions estimated by Global Climate Models for 2050 and 2070. The extinction risk and quasi-extinction were estimated for this population considering two critical huemul abundance levels (15 and 30 individuals) for persistence. The population is currently in a quasi-extinction process, with extinction probabilities increasing with climate change. These results are crucial for conservation of species like huemul that have low densities and are threatened by climate change.

Strength of correlation between wildlife collision data and hunting bags varies among ungulate species and with management scale

Most European ungulate species are increasing in numbers and expanding their range. For the management and monitoring of these species, 64% of European countries rely on indirect proxies of abundance (e.g., hunting bag statistics). With increasing ungulate numbers, data on ungulate-vehicle collisions (UVC) may provide an important and inexpensive, complementary data source. Currently, it is unclear how bag statistics compare with UVC. A direct comparison of these two indices is important because both are used in ungulate management. We evaluated the relationship between UVC and ungulate hunting bags across bioclimatic, regional, and local scales, using five time lags (t−3 to t+1) for the five most common wild ungulate species in Sweden. For all species, hunting bags and UVC correlated positively, but correlation strength and time lags varied across scales and among species. The two indices correlated most strongly at the local management scale. Correlation between both indices was strong for the smaller deer species and wild boar, in particular, but much weaker for moose where we found the best fit using a 2-year time lag. For the other species, indices from the same year correlated best. We argue that the reason for moose data behaving differently is that, in Sweden, moose are formally managed using a 3-year time plan, while the other species are not. Accordingly, moose hunting bags are influenced more strongly by density-independent processes than bags of the other species. Consequently, the mismatch between the two indices may generate conflicting conclusions for management depending on the method applied.

Eurasian lynx fitness shows little variation across Scandinavian human-dominated landscapes

Despite extensive research on the ecology and behavioural adaptations of large carnivores in human-dominated landscapes, information about the fitness consequences of sharing landscapes is still limited. We assessed the variation in three consecutive components of female fitness: the probability of reproduction, litter size and juvenile survival in relation to environmental and human factors in a solitary carnivore, the Eurasian lynx (Lynx lynx), occurring in human-dominated landscapes in Scandinavia. We used demographic data from 57 radio-collared adult females between 1995-2011 (126 radio-years). Overall, the yearly probability of female reproduction was 0.80, mean litter size was 2.34 (range 1-4) and the probability to find a female that reproduced in the spring being accompanied by at least one offspring during the subsequent winter was 0.70. We did not find evidence that food availability was a key factor influencing female fitness. Female lynx may adapt to food availability when establishing their home ranges by adopting an obstinate strategy, ensuring a minimum amount of prey necessary for survival and reproduction even during periods of prey scarcity. In human-dominated landscapes, where sufficient prey are available for lynx, mortality risk may have a larger influence on lynx population dynamics compared to food availability. Our results suggest that lynx population dynamics in human-dominated landscapes may be mainly driven by human impacts on survival.

Can Protected Areas Mitigate Lyme Disease Risk in Fennoscandia?

This Forum article synthesizes the current evidence on the links between predator-prey interactions, protected areas and spatial variations in Lyme disease risk in Fennoscandia. I suggest key research directions to better understand the role of protected areas in promoting the persistence of diverse predator guilds. Conserving predators could help reducing host populations and Lyme disease risk in northern Europe. There is an urgent need to find possible win-win solutions for biodiversity conservation and human health in ecosystems facing rapid global environmental change.

Who's afraid of the big bad wolf? Variation in the stress response among personalities and populations in a large wild herbivore

Faced with rapid environmental changes, individuals may express different magnitude and plasticity in their response to a given stressor. However, little is known about the causes of variation in phenotypic plasticity of the stress response in wild populations. In the present study, we repeatedly captured individual roe deer (Capreolus capreolus) from two wild populations in Sweden exposed to differing levels of predation pressure and measured plasma concentrations of stress-induced cortisol and behavioral docility. While controlling for the marked effects of habituation, we found clear between-population differences in the stress-induced cortisol response. Roe deer living in the area that was recently recolonized by lynx (Lynx lynx) and wolves (Canis lupus) expressed cortisol levels that were around 30% higher than roe deer in the human-dominated landscape free of large carnivores. In addition, for the first time to our knowledge, we investigated the stress-induced cortisol response in free-ranging newborn fawns and found no evidence for hypo-responsiveness during early life in this species. Indeed, stress-induced cortisol levels were of similar magnitude and differed between populations to a similar extent in both neonates and adults. Finally, at an individual level, we found that both cortisol and docility levels were strongly repeatable, and weakly negatively inter-correlated, suggesting that individuals differed consistently in how they respond to a stressor, and supporting the existence of a stress-management syndrome in roe deer.

Fear or food - abundance of red fox in relation to occurrence of lynx and wolf

Apex predators may affect mesopredators through intraguild predation and/or supply of carrion from their prey, causing a trade-off between avoidance and attractiveness. We used wildlife triangle snow-tracking data to investigate the abundance of red fox (Vulpes vulpes) in relation to lynx (Lynx lynx) and wolf (Canis lupus) occurrence as well as land composition and vole (Microtus spp.) density. Data from the Swedish wolf-monitoring system and VHF/GPS-collared wolves were used to study the effect of wolf pack size and time since wolf territory establishment on fox abundance. Bottom-up processes were more influential than top-down effects as the proportion of arable land was the key indicator of fox abundance at the landscape level. At this spatial scale, there was no effect of wolf abundance on fox abundance, whereas lynx abundance had a positive effect. In contrast, at the wolf territory level there was a negative effect of wolves on fox abundance when including detailed information of pack size and time since territory establishment, whereas there was no effect of lynx abundance. This study shows that different apex predator species may affect mesopredator abundance in different ways and that the results may be dependent on the spatiotemporal scale and resolution of the data.

Variation in home range size of red foxes Vulpes vulpes along a gradient of productivity and human landscape alteration

Home range size is a fundamental concept for understanding animal dispersion and ecological needs, and it is one of the most commonly reported ecological attributes of free-ranging mammals. Previous studies indicate that red foxes Vulpes vulpes display great variability in home range size. Yet, there has been little consensus regarding the reasons why home range sizes of red foxes vary so extensively. In this study, we examine possible causes of variation in red fox home range sizes using data from 52 GPS collared red foxes from four study areas representing a gradient of landscape productivity and human landscape alteration in Norway and Sweden. Using 90% Local Convex Hull home range estimates, we examined how red fox home range size varied in relation to latitude, elevation, vegetation zone, proportion of agricultural land and human settlement within a home range, and sex and age. We found considerable variation in red fox home range sizes, ranging between 0.95 km² to 44 km² (LoCoH 90%) and 2.4 km² to 358 km² (MCP 100%). Elevation, proportion of agricultural land and sex accounted for 50% of the variation in home range size found amongst foxes, with elevation having the strongest effect. Red foxes residing in more productive landscapes (those in more southern vegetation zones), had home ranges approximately four times smaller than the home ranges of foxes in the northern boreal vegetation zone. Our results indicate that home range size was influenced by a productivity gradient at both the landscape (latitude) and the local (elevation) scale. The influence of the proportion of agriculture land on home range size of foxes illustrates how human landscape alteration can affect the space use and distribution of red foxes. Further, the variation in home range size found in this study demonstrates the plasticity of red foxes to respond to changing human landscape alteration as well as changes in landscape productivity, which may be contributing to red fox population increases and northern range expansions.

Linking landscape-scale differences in forage to ungulate nutritional ecology

Understanding how habitat and nutritional condition affect ungulate populations is necessary for informing management, particularly in areas experiencing carnivore recovery and declining ungulate population trends. Variations in forage species availability, plant phenological stage, and the abundance of forage make it challenging to understand landscape-level effects of nutrition on ungulates. We developed an integrated spatial modeling approach to estimate landscape-level elk (Cervus elaphus) nutritional resources in two adjacent study areas that differed in coarse measures of habitat quality and related the consequences of differences in nutritional resources to elk body condition and pregnancy rates. We found no support for differences in dry matter digestibility between plant samples or in phenological stage based on ground sampling plots in the two study areas. Our index of nutritional resources, measured as digestible forage biomass, varied among land cover types and between study areas. We found that altered plant composition following fires was the biggest driver of differences in nutritional resources, suggesting that maintaining a mosaic of fire history and distribution will likely benefit ungulate populations. Study area, lactation status, and year affected fall body fat of adult female elk. Elk in the study area exposed to lower summer range nutritional resources had lower nutritional condition entering winter. These differences in nutritional condition resulted in differences in pregnancy rate, with average pregnancy rates of 89% for elk exposed to higher nutritional resources and 72% for elk exposed to lower nutritional resources. Summer range nutritional resources have the potential to limit elk pregnancy rate and calf production, and these nutritional limitations may predispose elk to be more sensitive to the effects of harvest or predation. Wildlife managers should identify ungulate populations that are nutritionally limited and recognize that these populations may be more impacted by recovering carnivores or harvest than populations inhabiting more productive summer habitats.

Patterns of Lynx Predation at the Interface between Protected Areas and Multi-Use Landscapes in Central Europe

In Central Europe, protected areas are too small to ensure survival of populations of large carnivores. In the surrounding areas, these species are often persecuted due to competition with game hunters. Therefore, understanding how predation intensity varies spatio-temporally across areas with different levels of protection is fundamental. We investigated the predation patterns of Eurasian lynx (Lynx lynx) on roe deer (Capreolus capreolus) and red deer (Cervus elaphus) in both protected areas and multi-use landscapes of the Bohemian Forest Ecosystem. Based on 359 roe and red deer killed by 10 GPS-collared lynx, we calculated the species-specific annual kill rates and tested for effects of season and lynx age, sex and reproductive status. Because roe and red deer in the study area concentrate in unprotected lowlands during winter, we modeled spatial distribution of kills separately for summer and winter and calculated-the probability of a deer killed by lynx and-the expected number of kills for areas with different levels of protection. Significantly more roe deer (46.05-74.71/year/individual lynx) were killed than red deer (1.57-9.63/year/individual lynx), more deer were killed in winter than in summer, and lynx family groups had higher annual kill rates than adult male, single adult female and subadult female lynx. In winter the probability of a deer killed and the expected number of kills were higher outside the most protected part of the study area than inside; in summer, this probability did not differ between areas, and the expected number of kills was slightly larger inside than outside the most protected part of the study area. This indicates that the intensity of lynx predation in the unprotected part of the Bohemian Forest Ecosystem increases in winter, thus mitigation of conflicts in these areas should be included as a priority in the lynx conservation strategy.