RECENT RESEARCH | January – April 2021

Despite the essential role that vertebrate scavengers play in ecosystems, most studies have been conducted in Europe and North America, and there is a lack of information on vertebrate scavengers in vast regions of the world. Our aim was to describe the functioning and composition of the unknown vertebrate scavenger assemblage in the Gobi Desert, Mongolia, and determine how carcass size and habitat type affect species composition and carrion use. We monitored carcasses with camera traps and we also conducted observation points to survey the raptor community and identify the proportion of raptor species making use of the carcasses. We recorded eight vertebrate scavenger species (five birds and three mammals) by camera trap and seven raptors at observation points. Over half of the raptor species recorded at the observation points were also found feeding on carrion. The two most threatened species were only recorded in the mountain habitat. Furthermore, scavenger abundance and consumption rates were higher at large carcasses. This study highlights the importance of scavenging by raptors and other vertebrate scavengers for carrion elimination in ecosystems with extreme climatic conditions.

In species that live in sympatry, some dimensions of their ecological niche can overlap, but coexistence is possible thanks to segregation strategies, being the differential use of space and time one of the most frequent. Through a pioneer study in North-West Africa based on a camera-trapping survey, we studied ecology features of a carnivores’ community in the Middle Atlas Mountains, Morocco. We focused on how species shared (or not) the territory and their activity patterns. Camera trapping detected five carnivorous species: African golden wolf (Canis lupaster), red fox (Vulpes vulpes), domestic dog (Canis lupus familiaris), genet (Genetta genetta) and African wildcat (Felis lybica lybica). Generalized Linear Models confirmed different habitat selection patterns between these species. The presence of a small protected area or prey availability apparently were not determinant factors in the abundance of these species. Spatial segregation patterns were observed between the red fox with the domestic dog and between the red fox with the genet. Kernel density estimates showed strong temporal segregation of red fox and African golden wolf with regard to domestic dog, and suggested avoidance mechanisms for the triad red fox, genet and African golden wolf. Despite the influence of interspecific competition in the assembly of the community, human pressure was apparently the most relevant factor related with the spatio-temporal segregation in this territory.

Wolves (Canis lupus), a once widely distributed species, were systematically removed from many temperate zone ecosystems due to conflicts with humans. A change in human attitudes and cultural norms has brought about a recovery in some suitable areas, yet reintroductions are still controversial. Two notable reintroduction areas in the United States were Yellowstone and Isle Royale National Parks. Both proposals caused polarization and debate. In Yellowstone opposition focused on outside the park effects, mainly wolves killing livestock and wild game also desired by human hunters. At Isle Royale, opposition was mostly about human interventions into nature and impairment of wilderness values contrary to the spirit of 1964 Wilderness Act. Both locations had periods in the 20th century with and without wolves and the presence of wolves had a dampening effect on ungulate population fluctuations. Most outcomes of reintroduction at Yellowstone were predicted as the Environmental Impact Statement written beforehand correctly predicted 78% of the 51 outcomes that were examined. Wolves were too recently reintroduced to Isle Royale to make similar comparisons, but we conclude that intervention is not contrary to the Wilderness Act, nor author Howard Zahniser’s vision, partially because wolf reintroduction was a mitigation for human actions. Also, not intervening, or inaction, often perceived as safer, would have had more damaging impacts to ecosystem functioning.

Following massive persecution and eradication, strict legal protection facilitated a successful reestablishment of wolf packs in Germany, which has been ongoing since 2000. Here, we describe this recolonization process by mitochondrial DNA control-region sequencing, microsatellite genotyping and sex identification based on 1341 mostly non-invasively collected samples. We reconstructed the genealogy of German wolf packs between 2005 and 2015 to provide information on trends in genetic diversity, dispersal patterns and pack dynamics during the early expansion process. Our results indicate signs of a founder effect at the start of the recolonization. Genetic diversity in German wolves is moderate compared to other European wolf populations. Although dispersal among packs is male-biased in the sense that females are more philopatric, dispersal distances are similar between males and females once only dispersers are accounted for. Breeding with close relatives is regular and none of the six male wolves originating from the Italian/Alpine population reproduced. However, moderate genetic diversity and inbreeding levels of the recolonizing population are preserved by high sociality, dispersal among packs and several immigration events. Our results demonstrate an ongoing, rapid and natural wolf population expansion in an intensively used cultural landscape in Central Europe.

In this study, we present the first data concerning the anatomical, morphometrical, histological and histochemical study of the orbit, eye tunics, eyelids and orbital glands in South African Painted Dogs (Lycaon pictus pictus). The study was performed using eyeball morphometry, analysis of the bony orbit including its morphometry, macroscopic study, morphometry, histological examination of the eye tunics and chosen accessory organs of the eye and histochemical analysis. The orbit was funnel shaped and was open-type. There was a single ethmoid opening for the ethmoid nerve on the orbital lamina. The pupil was round, while the ciliary body occupied a relatively wide zone. The iris was brown and retina had a pigmented area. The cellular tapetum lucidum was semi-circular and milky and was composed of 14–17 layers of tapetal cells arranged in a bricklike structure. In the lower eyelid, there was a single conjunctival lymph nodule aggregate. One or two additional large conjunctval folds were observed within the posterior surface of the upper eyelids. The superficial gland of the third eyelid had a serous nature. The third eyelid was T-shaped and was composed of hyaline tissue. Two to three conjunctival lymph nodul aggregates were present within the bulbar conjunctiva of the third eyelid. The lacrimal gland produced a sero-mucous secretion. A detailed anatomic analysis of the eye area in the captive South African Painted Dogs females showed the similarities (especially in the histological examination of the eyetunics and orbital glands) as well as the differences between the Painted dog and the other representatives of Canidae. The differences included the shape and size od the orbita with comparison to the domestic dog. Such differences in the orbit measurements are most likely associated with the skull type, which are defined in relation to domestic dogs. The presented results significantly expand the existing knowledge on comparative anatomy in the orbit, eye and chosen accessory organs in wild Canidae.

Our work shows that, despite the persistence of persecutory actions, conservation activity has proved successful for the return of numerous wild mammals to different habitats, including the wolf. The human-wolf conflict is still described in all countries where the wolf is present. This is evidenced by the high number of damages on livestock, and the corpses of wolves found both in protected areas and in those where hunting is permitted. The diagnosis of road accidents, together with poisoning and poaching, are major causes of mortality. Although hunting records the highest percentage of kills in Spain, the demographic stability reported by the censuses suggests that this activity does not have a consistent influence on the Iberian wolf population’s survival. In Italy, where wolf hunting is prohibited, wolf populations are to be increasing. In some Italian situations, wolf attacks on horses seem to cause unwanted damage to foals, but they represent a very precious source of information about the habits of carnivores. A simple management plan would be sufficient to help the coexistence between the productive parts and the ecosystem services ensured by the presence of the wolf. The presence of hybrids is a negative factor.

Aim
To develop an updated distribution model and habitat suitability analysis for the Mexican wolf, to inform the recovery efforts in Mexico and the United States.

Location
Mexico and the southwestern United States.

Methods
We used an ensemble species distribution modelling (SDM) approach and a spatial analysis combining anthropogenic and ecological variables, including, for the first time, rangewide relative density estimates of wild ungulates, to determine the extent of suitable habitat for wolves within a region that includes the known historical range of the Mexican wolf and adjacent areas.
Results

The results showed that the modelled distribution of the Mexican wolf extended from central Arizona and New Mexico, and western Texas in the United States, southwards along the Sierra Madre Occidental and the Sierra Madre Oriental, to the high sierras of Oaxaca, in Mexico. The habitat suitability models indicated that large tracts (>81,000 km2) of high‐quality habitat still exist for the Mexican wolf in the southwestern United States, and the Sierra Madre Occidental and the Sierra Madre Oriental in Mexico, which could ensure recovery within its historical range.

Main conclusions
The recovery of the Mexican wolf is a complex, multidimensional socio‐ecological challenge, which requires binational cooperation guided by reliable information and robust scientific procedures. The next step is to carry out specific socio‐ecological studies and actions for selected candidate sites to assess their viability for hastening its recovery.

Previous studies have posited the use of acoustics-based surveys to monitor population size and estimate their density. However, decreasing the bias in population estimations, such as by using Capture–Mark–Recapture, requires the identification of individuals using supervised classification methods, especially for sparsely populated species like the wolf which may otherwise be counted repeatedly. The cryptic behaviour of Indian wolf (Canis lupus pallipes) poses serious challenges to survey efforts, and thus, there is no reliable estimate of their population despite a prominent role in the ecosystem. Like other wolves, Indian wolves produce howls that can be detected over distances of more than 6 km, making them ideal candidates for acoustic surveys. Here, we explore the use of a supervised classifier to identify unknown individuals. We trained a supervised Agglomerative Nesting hierarchical clustering (AGNES) model using 49 howls from five Indian wolves and achieved 98% individual identification accuracy. We tested our model’s predictive power using 20 novel howls from a further four individuals (test dataset) and resulted in 75% accuracy in classifying howls to individuals. The model can reduce bias in population estimations using Capture-Mark-Recapture and track individual wolves non-invasively by their howls. This has potential for studies of wolves’ territory use, pack composition, and reproductive behaviour. Our method can potentially be adapted for other species with individually distinctive vocalisations, representing an advanced tool for individual-level monitoring.

Reproductive variables constitute a key information to assess population dynamics and inform wildlife management. We estimated wolf (Canis lupus) litter size and reproductive phenology in Spain between 1987 and 2015 based on foetus or placental scar counts on 75 females. Three out of twenty-five subadults (12%) and 32 out of 41 adults (78%) were classified as reproductive females. The mean litter size was estimated in 35 females, being 5.67 in subadults, based on placental scar counting, and 5.54 to 6.00 in adults, estimated by foetus counting or placental scar counting, respectively. Pregnancy was observed in 13 adults, which were sampled in April (N = 7), May (N = 4) and June (N = 2). Hence, the main mating season was estimated to occur between February and March. To our knowledge, the referred data constitutes the most extensive and updated information available on wolf reproduction in Spain until today.

The eastern wolf (Canis lycaon), a species of conservation concern in Canada, is currently restricted to small fragmented populations in south-central Ontario and hybridizes with both encroaching gray wolves and coyote-like canids. We examined niche dynamics in canids undergoing hybridization to determine whether competition among individuals with coyote (Canis latrans) or gray wolf (Canis lupus) ancestry, or their related hybrids, could threaten persistence of the eastern wolf in south-central Canada. Our integrative approach combined extensive genotyping and comparative niche analyses across the hybrid zone to assess available and utilized niche space across all three parental species and their hybrids within the zone of admixture. We focused on detecting niche imbalances within the canid clade that indicate competitive threats, and used these data to identify specific geographic regions that disproportionately favor eastern wolves and might confer natural exclusion of competing canids. We detected low genetic and ecological differentiation among groups across the region. Niche dynamics in the admixture zone were dominated by gray wolf and coyote-like canids, with coyote-like canids in particular exhibiting niche space that overlapped entirely with eastern wolves. Conservation action for eastern wolves must either exploit the narrow niche space that differentiates them from other canids, representing ~5% of their currently occupied space, or accept whichever group dominates the landscapes regardless of genetic makeup. This study suggests that competitive disadvantage can limit species’ recovery efforts, and thereby potentially warrant management that targets factors promoting ecological differentiation between groups.

Habitat selection and movement are considered important factors for survival of game species when they are hunted by humans. To reduce their risk of predation, animals can adapt their behavior to their most abundant predator over time through experience. To test for learning capabilities in a long-lived ungulate, I used GPS-data of 19 male and 84 female moose (Alces alces) in two study areas in southern Sweden from 2008-2018. I matched the GPS-data with reproduction and survival data and analyzed movement rates and habitat selection in a heavily managed moose population. While not being a gregarious species, moose are expected to learn from non-lethal mortality when a female loses her calf to harvest. Hunters were more likely to harvest male moose that moved faster before the moose hunting season began. Female moose where more likely to get harvested when they selected more for open habitats. The results of my study suggest that female moose in my study areas increased their shyness in the next hunting season after losing a calf to harvest. Female moose became increased nocturnalactivity and increased their avoidance of open habitats. As they aged, female moose decreased their movement rates and avoided open habitats. Using these proxies for shyness indicates that being shyer is beneficial for moose to survive the hunting season. My study suggests that learning effects accumulate as moose age. Furthermore, my results help to understand the influence human hunters impose on behavior of moose in a heavily managed population.

Carrion represents an important resource for carnivores. Examining competition for carrion in a risk–reward framework allows for a better understanding of how predator guilds compete for and benefit from carrion. We used trail camera data to compare wintertime carrion use and vigilance behavior of four carnivores in Denali National Park and Preserve. We found that carrion use was dominated by wolves (Canis lupus) and wolverines (Gulo gulo), followed by red foxes (Vulpes vulpes) and coyotes (Canis latrans). Wolves and wolverines were twice as likely to visit a carcass as foxes and coyotes, and their visits were longer and more numerous. Our results suggest scavenging animals reduced their risk exposure primarily by reducing their use of carrion, with some evidence of increased vigilance at busy sites. We found that carrion use and behavior at carcass sites were influenced by the mortality type of the carcass, the age of the carcass, and the long-term intensity of wolf use in the area. Our results also suggest that wolves are the “top scavenger,” and indicate that intraguild competition for carrion strongly affects which species benefit from carrion, with larger and more aggressive species dominating.

The non-invasive methods, which do not need direct access and harassment of animals, are essential for biodiversity monitoring. For mammals, analyses of scats and hair samples, tracking and recording by remote cameras are among the most commonly used. The study aimed to verify the current status of animal populations using camera traps in Gorce National Park (GNP), located in the Polish Carpathians covered with the natural beech and spruce mountain forests. On average, 35 passive infra-red camera traps annually were deployed in GNP. The archived data from the period of December 2013 to December 2017 was processed. In total, there were 21087 recordings of animals with 23 different taxa of mammals including 17 large and medium-sized species. Shannon’s diversity index was H´= 1.908. Among ungulates, the most commonly observed species were red deer (Cervus elaphus; n=7898), followed wild boar (Sus scrofa; n=526) and roe deer (Capreolus capreolus; n=482). Three large carnivores i.e., grey wolf (Canis lupus), Eurasian lynx (Lynx lynx) and brown bear (Ursus arctos) were all regularly observed, though they belong to rare species in Poland and other neighbouring countries. The use of camera traps allowed us to distinguish lynx individuals and estimate the size of its local population. The European wildcat (Felis silvestris) which was not observed in GNP since the 90s, was surprisingly recorded by camera traps in 2015 and 2016. Additionally, we registered raccoon (Procyon lotor), an invasive alien species in Poland, which can pose a potential threat to local fauna. Similarly, domestic dogs (Canis lupus familiaris) and cats (Felis catus) were free-ranging in GNP without any confinement and far from the nearest human settlements. The collected information helped to improve management and conservation measures by GNP. We showed that this non-invasive method is particularly useful for the monitoring of elusive and individually recognizable animal species.

Studying how animals interact with their environment is fundamental to informing conservation and management efforts, especially when examining large, wide-ranging carnivores in human-dominated landscapes. We hypothesized that the home ranges of bears are configured to exploit supplemental food (corn) and avoid people. In 2004–2016, we tracked 10 brown bears from the Dinaric-Pindos population using GPS telemetry, then used Brownian bridge movement models to estimate their home ranges. We related seasonal home range size to circadian period and density of supplemental feeding sites using generalized linear mixed-effect models. We also used ecological-niche factor analysis to study habitat composition within home range core areas in study areas characterized by different levels of human encroachment. We found that home range size was inversely related to density of supplemental feeding sites, and bears had larger home ranges at night (x̅ = 103.3 ± 72.8 km2) than during the day (x̅ = 62.3 ± 16.6 km2). Our results also revealed that bears living in more human-influenced areas concentrated their use far from human settlements and agricultural lands but stayed close to supplemental feeding sites. Our data suggest that bears alter their space-use patterns at the home range level in response to anthropogenic land use and food availability.

We investigate if and how diets of gray wolves from the Yukon Territory, Canada, have changed from the Pleistocene (>52.8 ka BP to 26.5 ka BP [±170 y BP]) to the recent Holocene (1960s) using dental microwear analysis of carnassial teeth and stable isotope analyses of carbonates (δ¹³C_CO3 and δ¹⁸O_CO3) and collagen (δ¹³C_col and δ¹⁵N_col) from bone. We find that dental microwear patterns are similar between the Pleistocene and Holocene specimens, indicating that there has been no change in carcass utilization behaviours, where flesh, not bone, is primarily consumed. Based on minimal changes in δ¹³C_CO3 and δ¹³C_col values, we find that, over thousands of years, Yukon gray wolves have remained generalist predators feeding upon several large ungulate species. Interestingly, δ¹⁵N_col values suggest that the extinction of megafaunal species at ~11.7 Ka induced a shift from a diet comprised primarily of horse (Equus sp.) to one based on cervids (i.e. moose and caribou). Survival of large-bodied cervids, such as caribou (Rangifer tarandus), was likely key to wolf survival. Although gray wolves survived the end Pleistocene megafauna extinction and demonstrate a degree of ecological flexibility, we suggest that failure to preserve major elements of their current niche (e.G. caribou) may result in continued population declines, especially in the face of increasing anthropogenic influences.

Wildlife viewing within protected areas is an increasingly popular recreational activity. Management agencies are often tasked with providing these opportunities, yet quantitative analyses of factors influencing wildlife sightings are lacking. We analyzed locations of GPS-collared wolves and wolf sightings from 2945 trips in Denali National Park and Preserve, Alaska, USA, to provide a mechanistic understanding of how viewing opportunities are influenced by attributes of wolves and physical, biological, and harvest characteristics. We found that the presence of masking vegetation, den site proximity to the road, pack size, and presence of a wolf harvest closure adjacent to the park affected wolf sightings, and the influence of den proximity on sightings depended on harvest management. Wolf sightings increased with den site proximity to the road in years with a harvest closure adjacent to the park but not in the absence of the closure. The effect of the harvest closure on sightings was similar in magnitude to an increase in pack size by two wolves or a more than a two-fold decrease in masking vegetation. These findings were consistent across a 10-fold change in spatial resolution. Quantitative analysis of the factors influencing wildlife sightings provides valuable insight for agencies tasked with managing viewing opportunities.

Conservation and management efforts have resulted in population increases and range expansions for some apex predators, potentially changing trophic cascades and foraging behavior. Changes in sympatric carnivore and dominant scavenger populations provide opportunities to assess how carnivores affect one another. Cougars (Puma concolor) were the apex predator in the Great Basin of Nevada, USA, for over 80 years. Black bears (Ursus americanus) have recently recolonized the area and are known to heavily scavenge on cougar kills. To evaluate the impacts of sympatric, recolonizing bears on cougar foraging behavior in the Great Basin, we investigated kill sites of 31 cougars between 2009 and 2017 across a range of bear densities. We modeled the variation in feeding bout duration (number of nights spent feeding on a prey item) and the proportion of primary prey, mule deer (Odocoileus hemionus), in cougar diets using mixed‐effects models. We found that feeding bout duration was driven primarily by the size of the prey item being consumed, local bear density, and the presence of dependent kittens. The proportion of mule deer in cougar diet across all study areas declined over time, was lower for male cougars, increased with the presence of dependent kittens, and increased with higher bear densities. In sites with feral horses (Equus ferus), a novel large prey, cougar consumption of feral horses increased over time. Our results suggest that higher bear densities over time may reduce cougar feeding bout durations and influence the prey selection trade‐off for cougars when alternative, but more dangerous, large prey are available. Shifts in foraging behavior in multicarnivore systems can have cascading effects on prey selection. This study highlights the importance of measuring the impacts of sympatric apex predators and dominant scavengers on a shared resource base, providing a foundation for monitoring dynamic multipredator/scavenger systems.

Study was objectively conducted to assess status, trend, confiscated and seized trophy of wildlife fauna and its legitimate deed. Division forest offices of Kathmandu, Lalitpure and Bhaktapur were taken for study area. The dimensions of the captured trophies were measured, 25 key informants were interviewed. Similarly, documents like register, cases filed and decision register were reviewed. Result showed that, Panthera tigris, Uncia uncial, Neofelis nebulosa, Canis lupus, Prionailurus bengalensis and Gavialis gangeticus were key illegally traded species. Altogether 327 wildlife trophies were captured in Kathmandu valley. Illegally captured fauna were 12 mammals, 1 bird, 3 reptiles falls under endangered categories of IUCN Red List and 7 species were listedunder endangered of IUCN Red list following by CITES I. Total 97 trophies (32%) fall under mega carnivores. Total weight of confiscated scales of Pangolin was 47.74kg in Kathmandu valley. It was 140cm length and 36cm breadth of captured leopard in Kathmandu district. Kruskal Wallis test showed that, there was significant difference in number of confiscated body parts captured in Kathmandu, Lalitpur and Bhaktapur districts at 95% confidence level.Total 381 cases were recorded in Kathmandu valley. Co-efficient variances of case registered were 0.162, 0.264 and 0.212 in Kathmandu, Lalitpur and Bhaktapur districts respectively. MannKenall’s tau b correlation showed that value of correlation coefficient were 0.587,0.305 and 0.554 in Kathmandu, Lalitpurand Bhaktapur districts respectively. Total 698 persons were involved in wildlife crime. Maximum charge was US $1,626.90 in Bhaktapure district and maximum imprisonment period was 79 months in Kathmandu.

New field tests have assessed the effects of predator-induced stress on prey fitness, particularly in large carnivore-ungulate systems. Because traditional measures of stress present limitations when applied to free-ranging animals, new strategies and systemic methodologies are needed. Recent studies have shown that stress and anxiety related behaviors can influence the metabolic activity of the gut microbiome in mammal hosts, and these metabolic alterations may aid in identification of stress. In this study, we used NMR-based fecal metabolomic fingerprinting to compare the fecal metabolome, a functional readout of the gut microbiome, of cattle herds grazing in low vs. high wolf-impacted areas within three wolf pack territories. Additionally, we evaluated if other factors (e.g., cattle nutritional state, climate, landscape) besides wolf presence were related to the variation in cattle metabolism. By collecting longitudinal fecal samples from GPS-collared cattle, we found relevant metabolic differences between cattle herds in areas where the probability of wolf pack interaction was higher. Moreover, cattle distance to GPS-collared wolves was the factor most correlated with this difference in cattle metabolism, potentially reflecting the variation in wolf predation risk. We further validated our results through a regression model that reconstructed cattle distances to GPS-collared wolves based on the metabolic difference between cattle herds. Although further research is needed to explore if similar patterns also hold at a finer scale, our results suggests that fecal metabolomic fingerprinting is a promising tool for assessing the physiological responses of prey to predation risk. This novel approach will help improve our knowledge of the consequences of predators beyond the direct effect of predation.

Few field tests have assessed the effects of predator-induced stress on prey fitness, particularly in large carnivore-ungulate systems. Because traditional measures of stress present limitations when applied to free-ranging animals, new strategies and systemic methodologies are needed. Recent studies have shown that stress and anxiety related behaviors can influence the metabolic activity of the gut microbiome in mammal hosts, and these metabolic alterations may aid in identification of stress. In this study, we used NMR-based fecal metabolomic fingerprinting to compare the fecal metabolome, a functional readout of the gut microbiome, of cattle herds grazing in low vs. high wolf-impacted areas within three wolf pack territories. Additionally, we evaluated if other factors (e.g., cattle nutritional state, climate, landscape) besides wolf presence were related to the variation in cattle metabolism. By collecting longitudinal fecal samples from GPS-collared cattle, we found relevant metabolic differences between cattle herds in areas where the probability of wolf pack interaction was higher. Moreover, cattle distance to GPS-collared wolves was the factor most correlated with this difference in cattle metabolism, potentially reflecting the variation in wolf predation risk. We further validated our results through a regression model that reconstructed cattle distances to GPS-collared wolves based on the metabolic difference between cattle herds. Although further research is needed to explore if similar patterns also hold at a finer scale, our results suggests that fecal metabolomic fingerprinting is a promising tool for assessing the physiological responses of prey to predation risk. This novel approach will help improve our knowledge of the consequences of predators beyond the direct effect of predation.

The white‐tailed deer (Odocoileus virginianus) is an ecologically important species in forests of North America. Effective management of forests requires accurate, precise estimates of deer population abundance to plan and justify management actions. Spotlight surveys in combination with distance sampling are a common method of estimating deer population abundance; however, spotlight surveys are known to have serious drawbacks such as high costs and sampling biases. Therefore, we tested the effectiveness of enumerating deer from unmanned aerial vehicle (UAV) flights, conducted 1 and 6 March 2018, to develop population and density estimates in 2 United States National Parks: Harpers Ferry National Historic Park (HAFE) and Monocacy National Battlefield (MONO). Concurrent spotlight surveys at MONO enabled us to compare estimates obtained by the 2 methods. Deer density estimates by 4 observers of UAV‐obtained thermal imagery from HAFE were 94.5 ± 3.9 deer/km2. Concurrent UAV and spotlight surveys at MONO found 19.7 ± 0.5 deer/km2 and 6.4 ± 4.9 deer/km2, respectively; suggesting that spotlight surveys may significantly underestimate deer densities. Despite the logistical challenges to UAV operation, our findings demonstrate that UAVs will become an invaluable tool for wildlife management as technology improves. © 2021 The Wildlife Society. This article has been contributed to by US Government employees and their work is in the public domain in the USA.

Context

Habitat loss is widely recognized as the main driver of biodiversity loss around the globe, yet the effects of habitat fragmentation on biodiversity have been extensively debated in recent years.

Objectives

We used a robust dataset of medium and large-sized mammals to test (a) the Habitat Amount Hypothesis, which postulates that species richness can be mainly predicted by the total amount of habitat surrounding the sampling site, and (b) the effects of habitat fragmentation per se, which may be expected to be weak or mainly positive on species richness.

Methods

We compiled information on the occurrence of mammal species in 166 forest fragments across the Atlantic Forest. For each forest fragment, we extracted information on patch size, percentage of forest cover (a proxy for habitat amount), and edge density and number of fragments (fragmentation metrics). We related these metrics to mammalian richness considering separately for all species, forest-dependent species, disturbance-tolerant species, and different trophic guilds.
Results

All richness measures strongly declined with decreasing forest cover, yet were unaffected by patch size, number of patches and edge density. The only exception occurred with herbivore richness, which was affected by number of patches. However, we found fragmentation per se effects only for herbivore richness.
Conclusions

Our results show that mammal richness increased with habitat amount at the landscape, whereas habitat fragmentation per se had significant negative impacts on herbivores only. We therefore recommend maintaining highly forested landscapes and restoring severely deforested areas, being essential for ensuring high richness of mammals.

The increasing animosity towards wolves (Canis lupus) by livestock-keeping nomads in Mongolia and the accompanying conflicts highlight the urgent need for knowledge about the feeding behavior of wolves, since information on the feeding ecology of wolves in Mongolia is rare, especially in the mountain taiga and mountain forest steppe regions of Northern Mongolia. Those regions are characterized by a relatively high wildlife diversity and are sparsely populated by humans. To face this problem, 137 wolf scats were collected in the Khentii Mountain range in Northern Mongolia between 2008 and 2012. Almost all wolf faeces contained remnants of wild ungulates, which made up 89% of the consumed biomass. Siberian roe deer (Capreolus pygargus) was the most important and positively selected prey species. It was followed by red deer (Cervus elaphus) and wild boar (Sus scrofa), which was negatively selected by wolves. Wolves also fed on buffer prey species such as lagomorphs and small mammals. No evidence of domestic ungulates was found in the wolf diet. Thus, near-natural habitats with a diverse fauna of wild animals are important to limit livestock depredation.

We evaluated local communities’ fear of wolves in a scenario of wolf attacks on people and livestock in Western Iran. In particular, we investigated the interaction between experiences of wolf attacks (both on people and livestock) and three factors: behavioral action (management action, e.g., livestock carcass management), religious (e.g., the belief that wolves can be a curse if harmed by humans), and cultural norms (e.g., village elders have taught their children not to kill or harm wolves). We surveyed 400 randomly chosen households throughout the villages located in Hamadan province, Iran. Participants (mean age = 48.5 years) reported experiences of wolf attacks on people and on livestock in 40% and 60% of interviews, respectively. The majority of the respondents were afraid of seeing a wolf in the wild (66.5%). The majority of interviewees abandoned their livestock carcasses near agricultural lands, rangelands, and rural areas. Our results suggest that cultural factors play an active role in allaying fear of wolves, and this influence occurs regardless of having or not having experiences of wolf attacks. However, experiences of wolf–livestock attacks did not have a meaningful role in decreasing or increasing the effect of culture, religion, and behavior on fear. Efforts to reduce human fear of wolves should consider minimizing risky encounters for people, particularly focusing on unsupervised children (<12 years old). Training programs on how to properly handle livestock carcasses (e.g., appropriate methods of disposal and not abandoning livestock carcasses close to human settlements) may reduce the frequency of wolf attacks.

Gray wolf (Canis lupus) populations are expanding across Europe, which leads to an increase in their interactions with people and domestic animals, including dogs. Attacks on hunting dogs are becoming a major cause for conflicts between wolves and hunters in many countries, including Croatia, where this conflict has increased dramatically in recent years. To better understand the conflict and possible causes behind the attacks, we conducted a survey among Croatian hunters to investigate the trends and characteristics of the attacks. A total of 103 hunting dogs were reported as attacked by wolves in 2010–2018 with a significantly increasing trend. The attacks were fatal for 86% of the attacked dogs and among the dogs killed, 96% were at least partly consumed by the wolves. The most frequently attacked dogs were about 3 years old (47%), males (82%), and weighing 10–20 kg (62%) and belonged to scent hounds and related breeds. In respect to the breed, dogs were not attacked randomly, but we observed significant selection for tricolor hound, while Balkan hound, the Istrian hound, and the Posavina hound were avoided according to availability. Majority (64%) of dogs were killed during drive hunts on wild boar and highest frequency of attacks was recorded in the Split–Dalmatia County. More dogs were attacked in counties with more livestock and fewer wild prey, but correlations were not significant. Results suggest that wolves likely perceived dogs as potential prey and indicate some of the potential measures that could be used to mitigate the conflict.

Interference competition occurs when two species have similar resource requirements and one species is dominant and can suppress or exclude the subordinate species. Wolves (Canis lupus) and coyotes (C. latrans) are sympatric across much of their range in North America where white‐tailed deer (Odocoileus virginianus) can be an important prey species. We assessed the extent of niche overlap between wolves and coyotes using activity, diet, and space use as evidence for interference competition during three periods related to the availability of white‐tailed deer fawns in the Upper Great Lakes region of the USA. We assessed activity overlap (Δ) with data from accelerometers onboard global positioning system (GPS) collars worn by wolves (n = 11) and coyotes (n = 13). We analyzed wolf and coyote scat to estimate dietary breadth (B) and food niche overlap (α). We used resource utilization functions (RUFs) with canid GPS location data, white‐tailed deer RUFs, ruffed grouse (Bonasa umbellus) and snowshoe hare (Lepus americanus) densities, and landscape covariates to compare population‐level space use. Wolves and coyotes exhibited considerable overlap in activity (Δ = 0.86–0.92), diet (B = 3.1–4.9; α = 0.76–1.0), and space use of active and inactive RUFs across time periods. Coyotes relied less on deer as prey compared to wolves and consumed greater amounts of smaller prey items. Coyotes exhibited greater population‐level variation in space use compared to wolves. Additionally, while active and inactive, coyotes exhibited greater selection of some land covers as compared to wolves. Our findings lend support for interference competition between wolves and coyotes with significant overlap across resource attributes examined. The mechanisms through which wolves and coyotes coexist appear to be driven largely by how coyotes, a generalist species, exploit narrow differences in resource availability and display greater population‐level plasticity in resource use.

Predation and scavenging are pervasive ecological interactions in both terrestrial and aquatic environments. The ecology, evolution and conservation of scavengers, and especially predators, have received wide scientific attention and public awareness. However, the close connection that exists between predation and scavenging has not been made explicit until recently [1,2,3]. The propensity to hunt or scavenge a prey may vary within individuals, among different individuals within a population, and among different populations and species, depending on an intricate array of both intrinsic (e.g., morphology, body condition) and extrinsic (e.g., availability of alternative food sources) factors. In turn, the recognition that carnivorous animals may obtain meat by either hunting prey or scavenging their carcasses has profound implications, from individual morphology, physiology, and behavior to population, community, and ecosystem structure and functioning [1,2,3,4,5].
Given the novelty of this integrative research topic, many relevant questions have yet to be resolved. This Special Issue, through the three research papers and the three reviews that comprise it, aims to deal with some of these questions from diverse perspectives and methodological approaches.

In the first paper of this SI, Ordiz et al. [6] describe, in detail, the predatory and scavenging behavior of wolves (Canis lupus) and bears (Ursus arctos) in a Swedish area to understand the intrinsic and extrinsic conditions that favor the coexistence of these competing top carnivores. They show that bears and wolves were connected by frequent indirect interactions, mainly through bear scavenging of wolf kills. Scavenging by bears diminished in the moose calving season, when both carnivores turned to the abundant and vulnerable calves as the main food source. Additionally, not all bears were equally prone to scavenging wolf kills, as these carcasses were avoided by females with cubs of the year, i.e., the bear population sector that is more vulnerable to predation.

Teurlings et al. [7] explore a major anti-scavenger strategy of the other top carnivore, the Eurasian lynx (Lynx lynx). To prevent scavenger access to the remains of large prey, and thus to secure subsequent meals, lynxes and other felids usually hide their kills by covering them with different materials, such as vegetation and snow. This study, conducted in an area of southeastern Norway, shows that this caching behavior is an efficient anti-scavenger strategy, as cached prey (namely, roe deer, Capreolus capreolus) were discovered later than non-cached prey by both vertebrate (especially, birds) and invertebrate scavengers. These results are crucial to fully explain the functional responses of lynxes to their prey, and lynx–prey dynamics in general.
In the next empirical study, Teurlings et al. [8] further focus on the Eurasian lynx–roe deer system to investigate whether above-ground ecological processes linked to predation can trigger cascading effects on below-ground processes via carrion supply and decomposition. Unlike similar studies conducted in other systems, Teurlings et al. did not detect any effect of carcass remains on key chemical parameters of soil and vegetation about two years after death. These findings could be explained by the relatively small size of roe dear carcasses and by their efficient consumption by lynxes and scavengers.

The first review of this SI, made by Luna et al. [9], compares the scientific effort that has been devoted to date to predation and scavenging processes in urban habitats, which are increasingly represented in the planet Earth. The authors found that predation has been far more studied than scavenging. Moreover, urban ecologists became interested in scavenging several decades later than predation. The study species and areas of articles on scavenging were a subset of the species and areas studied in articles on predation. Luna et al. conclude that proper recognition of both the predatory and scavenging facets of carnivores will be needed to fully understand their role in urban food webs and their ecological consequences for urban environments.

A key question in predation–scavenging research is to identify the adaptations that make a species successful in exploiting a given niche within the predation–scavenging gradient. In this line, Potier [10] reviews the visual specializations associated with predatory and scavenging diurnal raptors. He finds that the eye size relative to body mass, as well as binocularity (as opposed to an enlarged field of view), increases towards the predation extreme of the gradient. He also identifies a qualitative anatomical difference between typical predators and more opportunistic and scavenger species, with the former having a second, temporally positioned fovea (probably used during prey capture) in addition to the central fovea that occurs in all species. These findings highlight the close relationship between visual system specializations and foraging ecology, which was often unrelated to phylogeny.

In the last contribution to this SI, Moleón and Sánchez-Zapata [11] reveal the important, though largely overlooked, role that carrion plays in the landscapes of fear and disgust. By reviewing the scientific literature, they identify the main ways in which carrion may be scary and disgusting, namely the principal interaction pathways between carcasses and their visitors (both carnivore and herbivore species) that expose the former to predators (see Ordiz et al. [6] for an empirical example in this SI) and parasites at carcass sites. In addition, they identify major knowledge gaps, which are mostly related to the disgusting facet of carrion. The presented conceptual framework may help to understand animal behavior and ecological processes, including cascading effects, around carrion resources.
The papers and reviews of this SI are proof of the explicit interest in the relationship between predation and scavenging that has currently pervaded many research groups worldwide. Nevertheless, as evidenced by this SI, important knowledge gaps still arise. For instance, investigations into marine, freshwater, and tropical terrestrial environments, as well as on invertebrates, would be especially welcome. I hope this SI may contribute to inspire future research ideas and effort on this general topic. Overall, the growing body of scientific knowledge on the interface between predation and scavenging will definitely dismiss the traditional view that they are disconnected ecological processes.

As 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.

Understanding how mesopredators manage the risks associated with apex predators is key to explaining impacts of apex predators on mesopredator populations and patterns of mesopredator space use. Here we examine the spatial response of coyotes (Canis latrans Say, 1823) to risk posed by wolves (Canis lupus Linnaeus, 1758) using data from sympatric individuals fitted with GPS collars in subarctic Alaska, USA, near the northern range limit for coyotes. We show that coyotes do not universally avoid wolves, but instead demonstrate season-specific responses to both wolf proximity and long-term use of the landscape by wolves. Specifically, coyotes switched from avoiding wolves in summer to preferring areas with wolves in winter, and this selection was consistent across short-term and longer term temporal scales. In the summer, coyotes responded less strongly to risk of wolves when in open areas than when in closed vegetation. We also demonstrate that coyotes maintain extremely large territories averaging 291 km2, and experience low annual survival (0.50) with large carnivores being the largest source of mortality. This combination of attraction and avoidance predicated on season and landcover suggests that mesopredators use complex behavioral strategies to mediate the effects of apex predators.

Spatial memory plays a role in the way animals perceive their environments, resulting in memory-informed movement patterns that are observable to ecologists. Developing mathematical techniques to understand how animals use memory in their environments allows for an increased understanding of animal cognition. Here we describe a model that accounts for the memory of seasonal or ephemeral qualities of an animal’s environment. The model captures multiple behaviors at once by allowing for resource selection in the present time as well as long-distance navigations to previously visited locations within an animal’s home range. We performed a set of analyses on simulated data to test our model, determining that it can provide informative results from as little as one year of discrete-time location data. We also show that the accuracy of model selection and parameter estimation increases with more location data. This model has potential to identify cognitive mechanisms for memory in a variety of ecological systems where periodic or seasonal revisitation patterns within a home range may take place.

Wolverines (Gulo gulo) were nearly eliminated from the contiguous U.S. by the mid-1920s, when they began to naturally recolonize portions of their historical range. Currently, the Greater Yellowstone Ecosystem in Wyoming represents the southernmost distribution. Using remote cameras, we detected two female wolverines in 2016 and 2017 in Wyoming, originally captured as juveniles. At nearly 11 and 12 y old, both were documented in the same areas where they appeared to set up home ranges previously, suggesting continued residency. The presence of long-lived females near the southern boundary of recolonization is important to the persistence of residents as well as population expansion. However, nearest habitat to the south is ≥130 km across open land atypical of wolverine habitat. Connectivity between island-like patches of habitat will be critical to continued recolonization, although active restorations may still be needed in areas unlikely to receive females through natural dispersal.

Knowledge about the connectivity among natural populations is essential to identify management units for effective conservation actions. Conservation-minded management has led to the recovery of large carnivore populations in northern Europe, possibly restoring connectivity between the two separated, but expanding brown bear (Ursus arctos) populations on the Scandinavian peninsula to the west and Karelia, a part of the large Eurasian population, to the east. The degree of connectivity between these populations has been poorly understood, therefore we investigated the extent of connectivity between the two populations using autosomal microsatellites and Y chromosome haplotypes in 924 male bears (the dispersing sex), sampled during a period of 12 years (2005–2017) across the transborder area where these two populations meet. Our results showed that the two populations are not genetically isolated as reported in earlier studies. We detected recent asymmetrical gene flow at a rate (individuals per generation) of 4.6–5.5 (1%) from Karelia into Scandinavia, whereas the rate was approximately 27.1–34.5 (8%) in the opposite direction. We estimated historical gene flow of effective number of migrants to be between 1.7 and 2.5 between the populations. Analyses of Y chromosome markers supported these results. Successful recovery and expansion of both populations led to the restoration of connectivity, however, it is asymmetric, possibly due to different recovery histories and population densities. By aligning monitoring between neighboring countries, we were able to better understand the biological processes across the relevant spatial scale.