Density Of Wild Ungulates Research Articles

Deer exclusion is necessary to promote post‐fire herbaceous regeneration in the understorey of a Mediterranean forest

The frequency of severe wildfires is on the rise in the Mediterranean Basin as a result of climate change and land abandonment. Recurrent wildfires may retard or impede ecosystem recovery, frequently requiring the implementation of restoration practices. In that context, a post‐fire deer exclusion experiment was conducted in a Mediterranean mixed forest ecosystem with high population densities of deer species (Fallow deer and Red deer). A deer exclusion area was established as a form of restoration intervention to promote post‐fire vegetation recovery. We surveyed plant species during the second and third springs after fire in both deer‐excluded and deer‐allowed areas in order to detect changes in the community. We analyzed the plant species composition, species diversity, and structure of herbaceous and woody plant communities. We also compared the frequency of annual and perennial herb species, functional groups, and post‐fire plant regeneration strategies. The main differences were due to differences between springs rather than of deer‐excluded and deer‐allowed plots. Deer consumed both woody and herbaceous species, favoring the assemblage of herbaceous over woody species. Deer favored the establishment of annual forbs, including unpalatable and/or exotic species, while limiting the abundance of graminoids. Observed deer impacts could have been magnified during the second spring by a drought. Our study demonstrates that deer exclusion can be an effective restoration practice for promoting post‐fire herbaceous regeneration in forests with significant densities of wild ungulates, although seasonal effects may override restoration practice effects.

High potential but little success: ungulate browsing increasingly impairs silver fir regeneration in mountain forests in the southern Swiss Alps

Abstract Sustainable regeneration of silver fir (Abies alba Mill.) is important for maintaining and improving the future resilience and protective capacity of mountain forests in the southern Swiss Alps. However, increasing densities of wild ungulates, such as red and roe deer, can hamper the regeneration success of silver fir. A comprehensive understanding of forest–wildlife interactions is essential to plan concrete measures for improving the adaptation potential of mountain forests. Here, we monitored the dynamics of natural silver fir regeneration in mountain protective forests. This study encompassed 30 unfenced permanent plots across two sites, Lostallo and Soazza, located in Valle Mesolcina in the southern Swiss Alps. These sites were selected for their comparable ecological characteristics related to silver fir regeneration, yet contrasting densities of mature, seed-bearing silver fir trees. We recorded the number of seedlings (<10 cm height) and saplings (10–200 cm height), and repeatedly assessed height growth, frequency, and intensity of ungulate browsing on saplings in the summers 2016, 2019, and 2022. In 2022, we additionally recorded the presence of browsing on other tree species in the unfenced plots and the height growth increments of silver fir saplings in pre-existing fences. On average, 509 silver fir seedlings/ha were present in the study area, but there was a lower density of saplings (382 saplings/ha). Between 2016 and 2022, the browsing frequency on silver fir saplings increased from 33 per cent to nearly 100 per cent, accompanied by a significant rise in browsing intensity. Furthermore, sapling height growth from 2019 to 2022 was significantly reduced or even negative in the unfenced plots as compared to the growth of saplings in the fenced plots. The observed seedling density indicated a good potential for natural regeneration of silver fir, irrespective of the differences in the density of seed-bearing trees between the two sites. However, the increased ungulate browsing impaired successful regeneration in the considered mountain forests in the southern Swiss Alps. Thus, without an effective control of ungulate browsing, silver fir may not be able to substantially contribute to the transition to more resilient and future-proof mountain forests.

The prohibition of recreational hunting of wild ungulates in Spanish National Parks: Challenges and opportunities

A new regulation has led to the prohibition of recreational hunting on estates located within Spanish National Parks (NPs). Before the ban, eleven NPs in Spain had already reported negative ecological consequences associated with high densities of wild ungulates. The new situation that has occurred after the ban signifies that policies with which to control populations of wild ungulates in NPs, most of which do not have a sufficient natural capacity to regulate populations, depend exclusively on the parks' authorities. The banning of recreational hunting implies a series of social, ecological, economic and logistic challenges. The control of wild ungulate populations in NPs requires: i) the legal basis for culling; ii) social acceptance as regards removing animals and the extractive procedures employed in NPs; iii) the long-term monitoring of wild ungulates and the damages that they cause, and iv) sufficient financial and human resources. A more integrated management and policy plan is, therefore, required, which should be supported by two pillars: i) the sustainability of natural resources and the conservation of functional environments, and ii) providing society with explanations regarding the need to manage wild ungulates. In order to bridge the potential gap between these key pillars, it is important to involve stakeholders in the decision-making processes concerning wild ungulate management. The forthcoming changes in Spanish NPs provide a promising opportunity to make a substantial improvement to wild ungulate management in these protected areas. This management approach could, moreover, serve as an example and be transferred to other protected spaces.

The Influence of Wild Ungulates on Forest Regeneration in an Alpine National Park

The browsing of wild ungulates can have profound effects on the structure and composition of forests. In the Swiss National Park, the density of wild ungulates, including red deer (Cervus elaphus), ibex (Capra ibex), and chamois (Rupicapra rupicapra), is exceptionally high due to strict protection and the absence of large predators. We examined count data of larch (Larix decidua), cembra pine (Pinus cembra), spruce (Picea abies), upright mountain pine (Pinus mugo subsp. uncinata), and mountain ash (Sorbus aucuparia) of four sampling years between 1991 and 2021, and modelled how topographic and location factors affected the probability of browsing on saplings of larch, cembra pine, and spruce. Despite the high density of wild ungulates, the number of saplings and young trees has increased over the past 30 years. The probability of browsing on saplings was highest for larch at a height of 10–40 cm and increased with increasing elevation. In our study area, open grasslands are mainly located above the tree line, which might explain the positive correlation between elevation and the probability of browsing. Further, the probability of browsing was related to exposition and slope, diversity of tree species, and disturbance by humans. It appears that in the investigated part of the Swiss National Park, the potential of the forest to regenerate has increased despite the high densities of wild ungulates.

New models for wild ungulates occurrence and hunting yield abundance at European scale

The goal of this report is i) to model the occurrence and hunting yield (HY) density of wild ungulates not only for widely distributed species in Europe, but also for those ones which have a constrained distribution and ii) to compare the output of occurrence with observed HY. Random Forest function was used for modelling occurrence of species. We used occurrence data available from the past 30 years, and HY data (period 2015-2020) from records collected by ENETWILD. Like previous models based on HY, the response variable was the maximum number of wild ruminants annually hunted in 2015-2020 hunting seasons divided by the area (km2) of the corresponding administrative unit (HY density). Models based on HY were statistically downscaled to make predictions to 10x10km squares. Occurrence data models indicated a good predictive performance for most species, showing that the model framework proposed have improved results in comparison to previous models. The transferability of models into new regions was limited by the exposure of species to environmental conditions. As for HY models, the calibration plots showed a good and linear predictive performance for widely distributed species, as well as constrained distributed species. Overall, our results were consistent with the expected abundance distribution of widely distributed species. The removal of zeros on the validation datasets affected the calibration plots of all regions, showing a better predictive performance when zeros were removed for widely distribution species, but the opposite was evidenced for species with limited distributions. We conclude that (i) the importance of co-correlation variables when variable importance is inferenced from random forest model results, (ii) manipulation presence and absence locations could yield further improvement in occurrence model outputs, and (iii) HY model projections displayed good abundance patterns for most of species, showing that the three frameworks proposed were a good approximation for modelling the distribution of wild ungulates HY, although it should be explored how to improve the results when distribution is patchy.

Habitat suitability map of Ixodes ricinus tick in France using multi-criteria analysis.

The tick Ixodes ricinus is widely distributed across Europe and is responsible for the transmission of several pathogens to humans and animals. In this study, we used a knowledge-based method to map variations in habitat suitability for I. ricinus ticks throughout continental France and Corsica. The multi-criteria decision analysis (MCDA) integrated four major biotic and abiotic factors known to influence tick populations: climate, land cover, altitude and the density of wild ungulates. For each factor, habitat suitability index (HSI) values were attributed to different locations based on knowledge regarding its impact on tick populations. For the MCDA, two methods of factor combination were tested, additive and multiplicative, both which were evaluated at the spatial scales of departments and local municipalities. The resulting habitat suitability maps (resolution=100x100 m) revealed that conditions are suitable for I. ricinus over most of France and Corsica. Particularly suitable habitats were located in central, north-eastern and south-western France, while less-suitable habitats were found in the Mediterranean and mountainous regions. To validate the approach, the HSI scores were compared to field data of I. ricinus nymph abundance. Regardless of scale, the correlation between abundance indicator and HSI score was stronger for the additive than for the multiplicative approach. Overall, this study demonstrates the value of MCDA for estimating habitat suitability maps for I. ricinus abundance, which could be especially useful in highlighting areas of the tick's distribution where preventive measures should be prioritised.

Cattle Grazing Effects on Vegetation and Wild Ungulates in the Forest Ecosystem of a National Park in Northeastern China

There is evidence that cattle grazing in forests limits big cat abundance. There is concern, too, about competition with wild ungulate prey through bottom-up effects on vegetation. Hence, there have been calls to remove or control forest livestock grazing in aid of restoring endangered large carnivores and their prey. To help inform scientific debate and decision making, we explored cattle-vegetation-prey dynamics in Northeast Tiger and Leopard National Park, northeast China and present a reappraisal of livestock grazing in the context of coexistence and an integrated approach to land use in China. Inside long-term forest grazing enclosures, wild boar (Sus scrofa) density increased with cattle density. Roe deer (Capreolus pygargus) density and occurrence probability of wild boar and roe deer were not influenced by cattle density. Wild ungulate densities were not related with the number of annual shoots, i.e., forage plant abundance. The presence/absence and abundance of annual shoots was not related with cattle density. Wild ungulate density had mixed associations with vegetation structure; arbor tree diameter at breast height (DBH) and habitat “openness” increased with cattle density. Finally, inside and outside enclosures had different vegetation characteristics and wild boar densities, while roe deer densities were equal. We conclude that cattle density and associated changes to vegetation have positive, negative, and neutral effects on two wild ungulate prey species. Each of these factors warrant consideration in evidence-based management decisions in regard to regulating ungulate community composition to support different large predators as preferred prey in core areas and corridors of habitats.

Detecting and Tracking the Positions of Wild Ungulates Using Sound Recordings.

Monitoring wild ungulates such as deer is a highly challenging issue faced by wildlife managers. Wild ungulates are increasing in number worldwide, causing damage to ecosystems. For effective management, the precise estimation of their population size and habitat is essential. Conventional methods used to estimate the population density of wild ungulates, such as the light census survey, are time-consuming with low accuracy and difficult to implement in harsh environments like muddy wetlands. On the other hand, unmanned aerial vehicles are difficult to use in areas with dense tree cover. Although the passive acoustic monitoring of animal sounds is commonly used to evaluate their diversity, the potential for detecting animal positions from their sound has not been sufficiently investigated. This study introduces a new technique for detecting and tracking deer position in the wild using sound recordings. The technique relies on the time lag among three recorders to estimate the position. A sound recording system was also developed to overcome the time drift problem in the internal clock of recorders, by receiving time information from GPS satellites. Determining deer position enables the elimination of repetitive calls from the same deer, thus providing a promising tool to track deer movement. The validation results revealed that the proposed technique can provide reasonable accuracy for the experimental and natural environment. The identification of deer calls in Oze National Park over a period of two hours emphasizes the great potential of the proposed technique to detect repetitive deer calls, and track deer movement. Hence, the technique is the first step toward designing an automated system for estimating the population of deer or other vocal animals using sound recordings.

Comparing unmanned aerial systems with conventional methodology for surveying a wild white-tailed deer population

Abstract Context Ungulate populations are subject to fluctuations caused by extrinsic factors and require efficient and frequent surveying to monitor population sizes and demographics. Unmanned aerial systems (UAS) have become increasingly popular for ungulate research; however, little is understood about how this novel technology compares with conventional methodologies for surveying wild populations. Aims We examined the feasibility of using a fixed-wing UAS equipped with a thermal infrared sensor for estimating the population density of wild white-tailed deer (Odocoileus virginianus) at the Cedar Creek Ecosystem Science Reserve (CCESR), Minnesota, USA. We compared UAS density estimates with those derived from faecal pellet-group counts. Methods We conducted UAS thermal survey flights from March to April of 2018 and January to March of 2019. Faecal pellet-group counts were conducted from April to May in 2018 and 2019. We modelled deer counts and detection probabilities and used these results to calculate point estimates and bootstrapped prediction intervals for deer density from UAS and pellet-group count data. We compared results of each survey approach to evaluate the relative efficacy of these two methodologies. Key results Our best-fitting model of certain deer detections derived from our UAS-collected thermal imagery produced deer density estimates (WR20204_IE1.gif, 95% prediction interval = 4.32–17.84 deer km−2) that overlapped with the pellet-group count model when using our mean pellet deposition rate assumption (WR20204_IE2.gif, 95% prediction interval = 4.14–11.29 deer km−2). Estimates from our top UAS model using both certain and potential deer detections resulted in a mean density of 13.77 deer km−2 (95% prediction interval = 6.64–24.35 deer km−2), which was similar to our pellet-group count model that used a lower rate of pellet deposition (WR20204_IE3.gif, 95% prediction interval = 6.46–17.65 deer km−2). The mean point estimates from our top UAS model predicted a range of 136.68–273.81 deer, and abundance point estimates using our pellet-group data ranged from 112.79 to 239.67 deer throughout the CCESR. Conclusions Overall, UAS yielded results similar to pellet-group counts for estimating population densities of wild ungulates; however, UAS surveys were more efficient and could be conducted at multiple times throughout the winter. Implications We demonstrated how UAS could be applied for regularly monitoring changes in population density. We encourage researchers and managers to consider the merits of UAS and how they could be used to enhance the efficiency of wildlife surveys.

Roads, forestry, and wolves interact to drive moose browsing behavior in Scandinavia

AbstractAs wild ungulate densities increase across Europe and North America, plant–herbivore interactions are increasingly important from ecological and economic perspectives. These interactions are particularly significant where agriculture and forestry occur and where intensive grazing and browsing by wild ungulates can result in economic losses to growing crops and trees. We studied plant–herbivore interactions in a moose (Alces alces)‐dominant system where forestry is a primary economy, the primary and secondary road networks are extensive, and wolves (Canis lupus) are recolonizing. Wolves and humans use low‐traffic, secondary roads, yet roadsides provide high‐quality and quantity browse for moose. Foraging theory predicts that moose will respond to riskier landscapes by selecting habitats that reduce predation risk, sacrificing feeding time or food quality. As food becomes limiting, however, animals will accept higher predation risk in search of food. We predicted that road avoidance behavior would be strongest within wolf territories. In areas without wolves, moose should select roadsides for their high forage availability. To test these predictions, we measured moose browsing and counted pellet groups as a proxy for habitat use each spring in Norway and Sweden between 2008 and 2018, in areas with and without wolves and at different distances from primary and secondary roads. We used generalized linear mixed models to evaluate drivers of the probability of browsing occurrence and browsing pressure. We found that browsing occurrence increased closer to secondary roads but decreased closer to primary roads. We also found browsing patterns to vary among tree species. For Scots pine (Pinus sylvestris), the browsing occurrence was two times higher in young forests relative to non‐young forests and decreased further from secondary roads. Wolf territory presence and probability had neutral or positive effect on browsing occurrence and pressure for all species. However, wolf territory presence had negative effects on browsing occurrence and pressure when interacting with secondary roads, young forest, or snow cover. We showed that roads can influence browsing patterns in Norway and Sweden. However, further research is needed, particularly in the face of continued infrastructure development in Scandinavia.

Unprecedented herbivory threatens rear-edge populations of Betula in southwestern Eurasia.

Mediterranean rear-edge populations of Betula, located at the southwestern Eurasian margin of the distribution range, represent unique reservoirs of genetic diversity. However, increasing densities of wild ungulates, enhanced dryness, and wildfires threaten their future persistence. A historical perspective on the past responses of these relict populations to changing herbivory, fire occurrence and climatic conditions may contribute to assessing their future responses under comparable scenarios. We have reconstructed vegetation and disturbance (grazing, fire) history in the Cabañeros National Park (central-southern Spain) using the paleoecological records of two small mires. We particularly focused on the historical range of variation in disturbance regimes, and the dynamics of rear-edge Betula populations and herbivore densities. Changes in water availability, probably related to the North Atlantic Oscillation (NAO) index, and land-use history have played a crucial role in vegetation shifts. Our data suggest that heathlands (mainly Erica arborea and E.scoparia) and Quercus woodlands dominated during dry phases while Sphagnum bogs and Betula stands expanded during wet periods. Betula populations survived past moderately dry periods but were unable to cope with enhanced land use, particularly increasing livestock raising since ~1,100-900cal. yr BP (850-1,050 CE), and eventually underwent local extinction. High herbivore densities not only contributed to the Betula demise but also caused the retreat of Sphagnum bogs. Ungulate densities further rose at ~200-100cal. yr BP (1750-1850 CE) associated with the historically documented intensification of land use around the Ecclesiastical Confiscation. However, herbivory reached truly unprecedented values only during the last decades, following rural depopulation and subsequent promotion of big game hunting. For the first time in temperate and Mediterranean Europe, we have used the abundances of fossil dung fungal spores to assess quantitatively that current high herbivore densities exceed the historical range of variation. In contrast, present fire activity lies within the range of variation of the last millennia, with fires (mainly human-set) mostly occurring during dry periods. Our paleodata highlight the need of controlling the densities of wild ungulates to preserve ecosystem composition and functioning. We also urge to restore Betula populations in suitable habitats where they mostly disappeared because of excessive human activities.

Recovery of Abies alba and Picea abies saplings to browsing and frost damage depends on seed source.

The density of wild ungulates has increased in the last century, and browsing has become a major driver of forest succession in the northern hemisphere. In addition, tree species are expected to respond differently to future climate conditions, especially an increased frequency of late frost events. The aim of this study was to analyze the influence of intraspecific genetic variation on the recovery of two tree species to frost and browsing. An experiment with saplings from 90 Abies alba and 72 Picea abies seed sources was conducted. Five‐year‐old saplings were clipped at three intensities before budburst in spring. Growth (height, diameter, leader shoot length, and biomass) and quality (e.g. stem form, multistemming, reaction type) were assessed before and 1–2 years after clipping or 3–4 years after natural frost events, and provenance differences were related to environmental differences at the seed source. For Abies, frost and clipping resulted in reduced height growth in the first year after the stress and reduced height for two (clipping) to four (frost) vegetation periods. Sapling biomass, diameter increment, and quality decreased after heavy clipping. For Picea, which grew twice as fast as Abies, such effects were only found after frost damage. Population differences were significant for both species for all investigated growth traits and for Picea also for some quality variables. The “reaction type” after browsing (e.g. new shoot, existing twig bending upward) seems to be species specific and independent of seed source. In contrast, the time lag between clipping and formation of a clear new leader shoot increased for Abieswith lower temperatures at the seed source. Lowland populations with warmer climates grew faster, and for Picea also qualitatively better, and recovered faster from leader shoot loss (Abies) or reacted at the uppermost meristem (Picea). Thus, the investigated stressors increased the existing differences among populations.

Determination of resource based stocking density of wild ungulates living in the floating meadows of Keibul Lamjao National Park, India

The stocking density of the globally threatened Eld's deer (Rucervus eldii eldii) and hog deer (Axis porcinus), living in the floating meadows of Keibul Lamjao National Park, India, were derived from the forage demand of each species and the availability of forage biomass in the meadows. The biomass production was estimated by harvesting the above-ground biomass every month for 2 years from 432 plots of size 1 m × 1 m that were protected by ungulate-proof enclosures. The actual intake of the ungulates was estimated from the percentage of dry matter consumed for each food plant species through micro-histological analysis. The populations of Eld's deer and hog deer that the meadows can support were calculated on the basis of the consumable dry matter available in the park, considering the variable thickness of the floating meadows. The estimated overall stocking densities of Eld's deer and hog deer were 0.141 ± 0.06 and 0.265 ± 0.12 individuals ha−1 or 15,581.54 ± 1171.6 kg of ungulate biomass. The stocking density varied significantly with meadow type for both the species, being higher for thick meadows. The best available areas of the park having 864.29 ha, can support 170.41 ± 11.4 Eld's deer and 319.36 ± 22.94 hog deer or 17,356.38 ± 912.02 kg of ungulate biomass with a maximum of 173.6 ± 4.21 Eld's deer and 325.46 ± 9.45 hog deer or 17,684.56 ± 697.3 kg of ungulate biomass in the monsoon season. The thin meadows with an area of 732.34 ha can support another 119.37 ± 12.78 and 225.44 ± 23.88 Eld's deer and hog deer respectively or 12,201.35 ± 922.74 kg of ungulate biomass. In similar resource constraint habitat, this study will be helpful in determining the optimal stocking density for the science based management of rangelands, especially for the conservation of wild grazers.

Biometrical measurements as efficient indicators to assess wild boar body condition

Body condition (i.e., the amount of the energy stored in organs and tissues) is a key parameter that has been related with health, reproductive performance and density of wild ungulates including the wild boar (Sus scrofa). In this wild pig, a reference method to assess body condition has not yet been agreed and different procedures have been used in recent literature. The aim of this work was to generate an easy and reliable method based on biometrical measurements and with the ability to predict body fat in live or die boars. For this, a total of 207 hunted wild boar from three Spanish populations with contrasting food availability were included in this study. Sex, age, biometrical parameters (body weight, total length and chest girth) and body condition indicators (brisket and rump fat thickness, kidney fat index (KFI), ratio between chest girth-total length and scaled mass index) were assessed for each animal. A boosted regression trees (BRT) approach was carried out to find models based on age, sex and biometrical features that predicted brisket fat thickness in the studied animals. BRT models including sex, body weight, total length and chest girth as explanatory variables were able to predict brisket fat thickness in wild boar (68–73% of deviance explained). These models were not influenced by the location of sampling and their predictive values showed a good agreement with real brisket fat thickness (94.1–95.6). Predictive values obtained in BRT models from each area also agreed with food availability suggesting this is a valid indicator of body condition of wild boar in a broad range of environmental conditions.

Impact of wild prey availability on livestock predation by snow leopards

An increasing proportion of the world's poor is rearing livestock today, and the global livestock population is growing. Livestock predation by large carnivores and their retaliatory killing is becoming an economic and conservation concern. A common recommendation for carnivore conservation and for reducing predation on livestock is to increase wild prey populations based on the assumption that the carnivores will consume this alternative food. Livestock predation, however, could either reduce or intensify with increases in wild prey depending on prey choice and trends in carnivore abundance. We show that the extent of livestock predation by the endangered snow leopard Panthera uncia intensifies with increases in the density of wild ungulate prey, and subsequently stabilizes. We found that snow leopard density, estimated at seven sites, was a positive linear function of the density of wild ungulates—the preferred prey—and showed no discernible relationship with livestock density. We also found that modelled livestock predation increased with livestock density. Our results suggest that snow leopard conservation would benefit from an increase in wild ungulates, but that would intensify the problem of livestock predation for pastoralists. The potential benefits of increased wild prey abundance in reducing livestock predation can be overwhelmed by a resultant increase in snow leopard populations. Snow leopard conservation efforts aimed at facilitating increases in wild prey must be accompanied by greater assistance for better livestock protection and offsetting the economic damage caused by carnivores.

The paradox of long-term ungulate impact: increase of plant species richness in a temperate forest.

Did high densities of wild ungulates cause a decline in plant species richness in a temperate oakwood? How did species composition change after nearly five decades? Did ungulates facilitate the spread of ruderal species and supress endangered species? Did dispersal strategies play a role in these processes? Krumlov Wood, SE Czech Republic. In 2012, we resampled 58 quasi-permanent vegetation plots first surveyed in 1960s. Between the surveys, 36 plots were enclosed in a game preserve with artificially high density of ungulates (mostly deer, mouflon and wild boar; ca. 55 animals per square km). We analysed the differences in temporal changes between plots inside and outside the game preserve, focusing on species diversity and composition. We assessed species characteristics relevant to grazing to understand compositional changes. Ungulates significantly increased alpha and gamma diversity and caused significant vegetation homogenization inside the game preserve. Vegetation homogenization and the increase in species richness resulted from massive enrichment by ruderal species. However, richness of endangered species decreased. Species dispersed by animals internally (endozoochory) increased, while species dispersed externally (epizoochory) or by wind (anemochory) decreased. Contrary to our expectations, our long-term data showed that artificially high ungulate densities substantially increased plant species richness. Apparently, the establishment of ruderal herbs was supported by frequent disturbances and ungulate-mediated dispersal. At the same time, species richness of non-ruderal plants did not change, probably because ungulates hindered the regeneration of woody species and maintained an open forest canopy. In conclusion, high ungulate density led to the spread of ruderal species, which in turn strongly contributed to the observed shift towards nutrient-richer conditions and taxonomically more homogenous communities.

Parental investment in two large raptors breeding in a high prey density area

We investigated the breeding behaviour of Bearded Vulture Gypaetus barbatus and Golden Eagle Aquila chrysaetos between 2008 and 2011 in the Stelvio National Park (the Alps, Italy), which harbours one of highest densities of wild ungulates in the Alps. Parental care behaviours (incubation and chick brooding, nest attendance, changeover, food provisioning and nestling feeding) were recorded at nests of both species (four Bearded Vulture and 14 Golden Eagle pairs). Differences in investment between sexes and periods were found in both species: the time spent in incubation and nest attendance was higher in females and decreased with the progress of the breeding season (from incubation to post-hatching and to pre-fledging). A significant effect of the interaction between sex and period was also found. Compared to the literature, our results suggest a lower contribution by Bearded Vulture males, whereas Golden Eagle males spent more time in incubation and nestling brooding than reported. The higher investment shown by Golden Eagle males in our study area may be due to the high availability of live prey and ungulate carrion, which could allow males to spend less time in hunting, resulting in more time at the nest. Most changeovers for both species took place in the central hours of the day. No difference in food provisioning was observed between the sexes of the two species, consistent with information available for Bearded Vultures, but not for Golden Eagles. The patterns we found revealed a female-biased investment (unexpected for the Bearded Vulture), although males significantly contributed to nest behaviour, especially during the incubation period (unexpected for Golden Eagles). The large amounts of natural prey and carrion in the study area may contribute to the nest behaviour of these large raptors.

To Eat or Not To Eat? The Diet of the Endangered Iberian Wolf (Canis lupus signatus) in a Human-Dominated Landscape in Central Portugal.

Livestock predation by large carnivores and their persecution by local communities are major conservation concerns. In order to prevent speculations and reduce conflicts, it is crucial to get detailed and accurate data on predators’ dietary ecology, which is particularly important in human dominated landscapes where livestock densities are high. This is the case of the endangered Iberian wolf in Portugal, an endemic subspecies of the Iberian Peninsula, which has seen its population distribution and abundance decline throughout the 20th century. Accordingly, the diet of the Iberian wolf was analyzed, using scat analysis, in a humanized landscape in central Portugal. From 2011 to 2014, a total of 295 wolf scats were collected from transects distributed throughout the study area, prospected on a monthly basis. Scat analysis indicated a high dependence of Iberian wolf on livestock. Domestic goat predominated the diet (62% of the scats), followed by cow (20%) and sheep (13%); the only wild ungulate present in the scat analysis was the wild boar (4% of the scats). Our results show that even though livestock constitute most part of wolves diet, different livestock species may represent different predation opportunities. We conclude that the high levels of livestock consumption may be a result of low diversity and density of wild ungulates that settles livestock as the only abundant prey for wolves. Our findings help on the understanding of the Iberian wolf feeding ecology and have implications for conflict management strategies. Finally, management implications are discussed and solutions are recommended.

Spatiotemporal dynamics of natural tree regeneration in unmanaged subalpine conifer forests with high wild ungulate densities

Increasing wild ungulate populations in the northern hemisphere led to extensive research on their influence on forest regeneration. According to the results of different studies, high ungulate densities may alter forest structure and composition, as well as inhibit forest regeneration. However, little is known about the long-term impact of large herbivores on forest dynamics at the landscape scale. Therefore, we studied forest regeneration in conifer forests of the highly protected Swiss National Park. We assessed sapling densities and apical shoot loss by repeated systematic sampling in 2003 and in 2011–2012 in two valleys featuring exceptionally high densities of wild ungulates of up to 86 individuals per vegetation-covered square kilometre during summer and 28 individuals per vegetation-covered square kilometre during winter. Mean apical shoot loss ranged between 2.9% and 10.6% depending on study site and assessment year. In addition to the increasing sapling densities, these results suggest that ungulates had little impact on tree establishment in the studied subalpine conifer forests. Additionally, sapling diversity was higher on plots repeatedly influenced by ungulates (apical shoot loss), suggesting rather positive effects of ungulates on sapling diversity. Habitat containing a mixture of forest and grassland without livestock or human disturbance provides a high-quality environment for ungulates, which likely explains the low impact of ungulates on forest regeneration in our study area.

The Impact of Climate Trends on a Tick Affecting Public Health: A Retrospective Modeling Approach for Hyalomma marginatum (Ixodidae).

The impact of climate trends during the period 1901–2009 on the life cycle of Hyalomma marginatum in Europe was modeled to assess changes in the physiological processes of this threat to public health. Monthly records of temperature and water vapour at a resolution of 0.5° and equations describing the life cycle processes of the tick were used. The climate in the target region affected the rates of the life cycle processes of H. marginatum: development rates increased, mortality rates in molting stages decreased, and the survival rates of questing ticks decreased in wide territories of the Mediterranean basin. The modeling framework indicated the existence of critical areas in the Balkans, central Europe, and the western coast of France, where the physiological processes of the tick improved to extents that are consistent with the persistence of populations if introduced. A spatially explicit risk assessment was performed to detect candidate areas where active surveys should be performed to monitor changes in tick density or persistence after a hypothetical introduction. We detected areas where the critical abiotic (climate) and biotic (host density) factors overlap, including most of the Iberian peninsula, the Mediterranean coast of France, eastern Turkey, and portions of the western Black Sea region. Wild ungulate densities are unavailable for large regions of the territory, a factor that might affect the outcome of the study. The risk of successfully establishing H. marginatum populations at northern latitudes of its current colonization range seems to be still low, even if the climate has improved the performance of the tick in these areas.