Biologists use a variety of methods to estimate productivity and resource selection of birds. The effectiveness and suitability of each method depends on the study's objectives, but is also influenced by many important traits, including detection probability, disturbance of focal birds and sampling frequency. We reviewed 504 greater sage-grouse Centrocercus urophasianus papers published from 1990 to 2019 to document the most common brood survey methods used by investigators and summarized if and how they used brood survey data to estimate brood survival and detection probability. Of the 504 papers, 16.1% (n = 81) had useful information relevant to the review. The most common methods included daytime visual surveys (46.9%; n = 38), daytime flush surveys (33.3%; n = 27), nocturnal spotlight surveys (19.8%; n = 16), radio-tagged chicks (16.0%; n = 13), wing surveys (9.9%; n = 8), brood routes (4.9%; n = 4) and pointing dogs (4.9%; n = 4). Fifty-nine of the 81 papers used >1 method, only 2 of the 81 papers measured or reported detection probability, and none reported the level of disturbance caused by the method. Studies varied widely regarding the age of the brood when brood fate was confirmed (x̄ = 44.4 days post-hatch, range 14–84 days). The frequency of brood sampling visits also varied greatly among studies (range = 1.19–3.85 surveys/brood/week) and this variation complicates comparison in fecundity and survival estimates across studies. Furthermore, 35 papers used >1 maternal behavior as purported indicators of brood fate, but none of them documented how accurate their indicators were. Future studies could reduce variance in estimates of sage-grouse fecundity and brood survival by employing empirical methods to estimate detection probability, standardizing brood sampling methods and conducting trials to document the effects of hen or brood capture, handling and flushing on brood survival estimates. Moreover, the accuracy of commonly used indicators of brood fate, including maternal behaviors, flocking behavior and distance moved after flush needs verification.

Assignment of Morelet's crocodile Crocodylus moreletii individuals into size groups or classes based on ecological and morphological similarities has not yet been associated with species-specific ontogeny related changes. Age or size of first reproductive behavior is not precisely known for C. moreletii, but differences in allometric patterns and relative cranial size between juveniles and adults might be used as an indicator of sexual maturity. In this study, a regression tree analysis was used to investigate the relationship between age and body size in 1266 crocodiles by using both simple and generalized linear models, with gender and origin (captivity or wild) as factors. Total length (TL), snout–vent length (SVL) and cranial length (CL) were used as predictor variables and the logarithm of body mass as the response variable. Four length intervals with well-defined thresholds (514, 899 and 1497 mm of TL) were established using all three predictors (TL, SVL and CL). Relationship between SVL and TL was described, and a strong positive relationship (r² = 0.98), unaffected by crocodile gender, was observed. The observed CL–TL and CL–SVL relationships were also positive but significantly different between males and females (p < 0.001) and length interval classes (p = 0.01). These results suggest that our estimated size thresholds seem to correspond to important ontogenetic changes in C. moreletii and that sexual maturity is closely related to size in this species, where sexual dimorphism in body length occurs, particularly in large individuals (size group IV).

Landscapes occupied by recovering carnivore populations in Europe are highly modified by human activity. It is unclear how recovering predators will adapt and sustain populations in highly altered landscapes, with most existing research focused on large carnivores. To address this we contrast population demographics and denning behaviour of a small carnivore, the pine marten Martes martes, in a semi-natural wooded landscape and a human-modified landscape with limited forest cover composed of conifer plantation, using radio-telemetry on 20 free-ranging individuals in Northern Ireland. In the semi-natural landscape, martens selected old growth, native forest making almost exclusive use of arboreal dens in living trees and standing deadwood. Martens persisted in the human-modified landscape but with lower population density and recruitment, with a male-biased sex ratio. In the human-modified landscape martens denned in marginal habitats such as scrub, heath and property boundaries, while making use of subterranean or man-made structures for dens in response to a lack of above ground denning opportunities. We demonstrate landscape change-induced differences in behaviour and population structure in a recovering carnivore. The results highlight the importance of evaluating the availability of denning sites in carnivore conservation and provide valuable management considerations, key to mitigating human–wildlife conflict as carnivores continue to recover and recolonise Europe.

Hunting, an activity conceptualized as part of wildlife management partnership between the state, landowners and hunting communities, is increasingly challenged by a decreasing hunter base. This has ecological, economic and socio-cultural consequences, and the issue of hunter recruitment deserves more scholarly and political attention. In Sweden, the number of individuals taking a hunting proficiency test is high even though the number of hunters has declined during the last few decades although with a recovery the last 12 months, indicating an under-utilized source of potential new hunters. We explore in an interview study with potential new hunters in Sweden what factors affect and motivate individuals to take the hunter proficiency test and to hunt. Our thematic analysis identifies structural, institutional and individual factors influencing hunting participation, such as social networks and access to land, rendering two ideal types of new hunters. We offer suggestions to help curb the negative trend of declining hunter numbers and we identify research gaps for future studies to address.

This review examines 128 items of primary and other literature to provide an insight into current knowledge of the effects of pheasant and red-legged partridge releasing and associated management for shooting on habitats and wildlife in the UK. It summarizes key findings and uses them to define sub-topic sections for which the effects are classified as positive, neutral or negative. This forms the basis of a numerical synthesis of effects and some overall conclusions.

Fifty-four directly related studies were identified, which defined 25 sub-topics or effects. A mix of positive, neutral and negative ecological consequences of releasing are described, for which the corresponding number of sub-topics approximately balance each other. Positive effects are usually a consequence of gamebird management activities, most negative effects are caused by the released birds themselves. The different spatial scales at which effects are likely to operate are identified, for example effects on generalist predators or of gamecrops occur at the landscape scale, while many habitat effects have a local impact.

Some local negative effects have relatively straightforward management solutions for example, by identifying and avoiding especially sensitive sites when locating release pens. The synthesis identifies seven negative effects associated with the increasing scale of releasing. Several positive effects are linked to economic considerations and are more likely to have greater impact at larger shoots. Pheasants released into woodland have more direct local effects than partridge releases on farmland.

The framework of sub-sections could be used as the basis for a more complex synthesis or weighted analysis for a particular set of ecological priorities. The review findings should be interpreted as representing a median type of shoot in terms of size and adherence to good practice over recent decades. They increase the awareness of potential conflicts, highlighting the need for best practice and what factors to consider for mitigation.

The increasing use of remote motion-sensitive photography recently led to an extension of distance sampling (DS) to accommodate camera trap data. Camera trap distance sampling (CTDS) has been proposed as a promising tool to estimate animal abundance, if temporally limited availability for detection is accounted for. However, the performance of CTDS in different field situations, and its reliability when single still images are used instead of videos or bursts of images remain untested. We used Alpine marmots Marmota marmota in the Stelvio National Park (Italy) to address three aims: 1) compare estimates of availability bias-corrected CTDS when using single still images with different set-ups to define sampling effort. For the ‘user-manual' set-up we used values of θ [angle of view] and t^* [recovery time, i.e. the shortest interval at which an animal can be detected] specified by the camera user manual. For the ‘empirical' set-up we estimated θ and t^* empirically. 2) Compare estimates of CTDS and line DS, both corrected for availability bias based on marmot behavior. 3) Compare estimates of CTDS corrected for availability bias with estimates obtained with capture–mark–recapture (CMR), accounting for the effective trapped area. Our results suggest that: 1) CTDS with ‘user-manual' set-up underestimated population size compared to the ‘empirical' set-up; 2) ‘empirical’ CTDS estimates were similar to those of line DS, but CTDS had lower precision; 3) availability bias-corrected CTDS underestimated abundance compared to CMR. Assessing camera settings empirically is crucial to reduce bias in CTDS estimators when single still images are used. Videos should be preferred as they allow choosing predefined snapshot moments and do not rely on settings that cannot be changed. Overall, our results support the use of CTDS as an alternative to DS, although proper availability-bias corrections and many cameras are needed to ensure accuracy and acceptable precision.

The grey seal became locally extinct in the southern Baltic Sea, Danish Straits and Kattegat in the early 1900s after prolonged culling campaigns. Here, we combine national monitoring and anecdotal data from Denmark, Sweden, Germany and Poland to report on the grey seal's recolonisation of those areas and the initial reestablishment of breeding colonies. Grey seal occurrence has steadily increased since year 2003 as evidenced by the coordinated Baltic Sea moult censuses. At the first census in 2003, there were 146 grey seals along the southern Baltic coasts of Sweden and Denmark, ca 1% of the total Baltic Sea population count. Since 2015, this has increased to 2000–2600 grey seals, or ca 7% of the total population count. Since the local extinction, there have been sporadic breeding events in the 1940s on sea ice around Bornholm and in the 1980s and 1990s on haul-outs in Kattegat. In 2003, the first two pups in the southern Baltic Sea were recorded at Rødsand, Denmark. This is to date the only site in the southern Baltic Sea with regular annual pupping since the recolonisation. Since 2000, there have also been sporadic breeding events in Danish Kattegat, southern Sweden, Poland and Germany. At Rødsand, there have been at least 3–10 pups recorded every year since initiation of monitoring in 2011, with an increasing tendency until 2017 with 10 pups counted, which subsequently decreased to 5–6 pups annually in 2018–2020. Compared to recolonising events in the Atlantic, the numbers of pups are low. This may be caused by differences in population dynamics, recolonisation distances, habitat and mortality and effects of rehabilitation programmes. It is likely that the breeding distribution will spread throughout the southern Baltic, Danish Straits and Kattegat if appropriate protection measures of seals and haul-outs are installed.

Killer whales, Orcinus orca, are a cosmopolitan species with large ecological and demographic variation across populations. Population-specific demographic studies are, therefore, crucial in accurately assessing the status and trends of local killer whale populations. Such studies require long-term datasets and remain scarce, particularly in the Southern Ocean where detailed population specific studies have only been conducted at a single archipelago – Îles Crozet. Here, we analysed 12 years of capture–recapture data (comprising nearly 90 000 identification photographs taken from 2006 to 2018) of killer whales at subantarctic Marion Island (46°54′S, 37°45′E) to estimate the abundance, survival and growth rate of this population. Demographic parameters were estimated using multistate capture recapture models, and Pradel Survival-Lambda and POPAN single-state models implemented in the program MARK. Annual survival probability (0.98 [95% CI: 0.96–0.99]) was constant over time, and no important differences between sexes and age-classes (calves, juveniles, adults) were found. This estimate of survival suggests a life expectancy of approximately 48 years. Realised mean population growth rate (λ) was 1.012 (0.987–1.037) with an estimated population size of 54 (54–60) individuals and a mean calving rate of 0.13 (0.06–0.20) calves born per year per reproductive female. The survival and reproduction rates of killer whales at Marion Island are similar to those of killer whale populations in the eastern North Pacific, Norway and Îles Crozet. However, subtle differences in survival and reproduction rates are present. These are likely the result of local differences in resource abundances, historical impacts on social structure and/or stressors. Also, the presence and scale of fisheries (legal and illegal) in the area may provide opportunities for direct interactions with fishing activities impacting survival and reproduction rates.

Grey wolf Canis lupus is often the main predator of moose Alces alces. Therefore it can be expected that moose are able to recognize the presence of wolves and react to them to avoid predation. We examined the effect of predation risk by wolves on movement patterns by moose in eastern Finland where moose and wolves have co-existed for centuries. The level of wolf predation risk experienced by 20 radio-collared adult moose was classified according to the proportion of their fixes in wolf territories. Our results suggest that moose adjust their movement speed according to the degree they are exposed to the presence of wolves. The adjustment occurred in summer but not in winter. In summer the moose more exposed to wolves moved faster than the moose less exposed to wolves. Season and the structure of the surrounding forests also affected moose movement patterns. Both movement speed and the linearity of movement decreased in winter and with increasing canopy cover. We suggest that by increased moving when exposed to higher risk of predation moose try to keep distance to the predator and/or try to keep themselves spatially and temporally unpredictable to their predator. Our results differ from those obtained in Scandinavia where no response of moose movement to predation risk by wolves has been detected. It might be that wolves' continuous presence in eastern Finland compared to Scandinavia provide a reason why moose in our study area reacted to the presence of wolves.

As nature-based recreational activities keep increasing, so does human pressure on wildlife. Several recent reviews provide a comprehensive overview of the impact of recreation on wildlife, but there is no comprehensive study of how humans perceive their own impact while participating in those activities. We fill this gap by summarizing the current state of research with a systematic review of 47 articles published between 1992 and 2018. It unveiled the current lack of research on sporting activities and on terrestrial mammals (in contrast to marine animals). In 43% of the surveys, most respondents were not aware of their impact on wildlife. The variables that were most often explored to explain the perception of disturbance was the experience and knowledge of the respondents. Some interesting results arose, such as the negative correlation between the level of knowledge of wildlife disturbance and awareness, or the transfer of the responsibility of disturbance on other user groups. Although several explanations are provided to explain these counterintuitive results, drawing general patterns stemming from the range of articles we reviewed was limited by the wide heterogeneity in researches aims, protocols and survey designs. In the conclusion we make recommendations to improve the comparability of future research.

Reintroductions of extirpated species are an important global conservation tool, yet can be challenging for wide-ranging species. Fences that help anchor reintroduced species to a target area may have deleterious effects on other wildlife. Here we assessed the wildlife-permeability of six bison drift fence designs at three spatial scales during the reintroduction of a wild herd of plains bison Bison bison to a 1200 km² wilderness area in Banff National Park, Canada. First, we used an array of remote cameras along fences to capture wildlife interactions for 12 species, and modelled crossing success, preferred crossing methods and age–sex class tendencies. Second, we investigated fence barrier effects on wildlife movement at the local scale using cameras that were in place before and after fence construction. Finally, we tested for changes in movement rates of migratory elk and resident wolves at the landscape scale using GPS collar telemetry. Our results point to a single fence design that maximizes permeability for several species with diverse crossing strategies, and can be adjusted to contain bison. Wildlife detections increased independently of fence construction in our broader study area. Fence construction did not affect wolf or elk movements and migration at a landscape scale even when fences were deployed to obstruct bison. Our study highlights the important role of wildlife permeable fences in the reintroduction of large mammals such as bison.

The wild boar is one of the most invasive species among large mammals in both its native and introduced ranges. This species represents a main threat for crops and biodiversity and a pest for the pig industry due to the rapid expansion of the African swine fever. Because of its peculiar life history traits, population control programmes and recreational hunting are usually unable to effectively reduce the number of wild boars. Therefore, a reliable approach based on appropriate, cost-effective, monitoring methodologies is urgently required. Effective monitoring should adopt effective sampling strategies, otherwise the detection of population trends can be erroneous and resulting in a mismatch of appropriate management actions. First, we review the status-of-the-art of wildlife monitoring with a special focus on wild boar and feral pigs. Then, we show that nocturnal distance sampling, carried out using thermal cameras, can be an effective monitoring technique for wild boar population assessment regardless of the characteristics of the sampled area. Using data from multiple surveys performed in four study areas in Italy, characterised by contrasting topography, habitats and level of environmental visibility, we found that the estimate of precision is generally good and almost independent of landscape conditions. A simple method to estimate visibility, which may empirically help wildlife managers to design effective nocturnal distance sampling surveys, is proposed. The bias of our population estimates is evaluated using simulations showing that in some areas the estimate is unbiased, while in others there is the tendency towards a negative bias. Based on reported results, we provide guidelines to perform nocturnal distance sampling of wild boar populations.

Ungulate–vehicle collisions pose a traffic safety issue as well as wildlife-conservation issues in many countries. While fences are recommended as reliable safety measures for motorways and other high-traffic volume roads, no generally accepted measures of the same efficiency are available for secondary roads. Odour repellents are applied in many central European countries, but contradictory results are available concerning their efficiency. We tested the effect of odour repellents on both a crossing frequency and the presence near roads of six individuals of roe deer over a period of five months (April–August 2019). The odour repellents were installed along two secondary roads, and along two semi-open habitats (forest–meadow and forest–arable land) alternately, in several phases. Two hypotheses were tested. The first one focused on the change in animal presence close to the profiles where the odours were applied, while the second hypothesis concerned a change in the number of crossings of the same profiles. The results demonstrate that no clear effect of odour repellents on roe deer behaviour in both hypotheses were obtained. Apart from the obtained results, we discuss the importance of the methodology. We conclude that this kind of study design is extremely sensitive to a number of factors with a potentially negative influence on the course of the study design.

Habitat use by cervids can have large effects on vegetation. Therefore, factors influencing habitat use are pertinent to ecology, nature conservation as well as management of forests and hunting. The aim of this study was to identify factors influencing habitat use by red and roe deer, Cervus elaphus and Capreolus capreolus, in the Lüneburger Heide, Germany. We used faecal pellet counts as an indicator of habitat use and applied generalized linear models to conclude that habitat use by both cervids was largely explained by the availability of food plants. In particular, the occurrence of bilberry Vaccinium myrtillus and deciduous trees such as beeches Fagus sylvatica were of major importance. Nonetheless, red and roe deer showed preferences for different plant species, but for both deer, the presence of large trees and conifers, with exception of young Norway spruce Picea abies providing shelter for roe deer, was less attractive. Furthermore, the proximity of mineral licks was important for both cervids. Relative to roe deer, red deer showed a stronger avoidance of well-used paths. Surprisingly, landscape features such as distance to settlements and elevated hunting standshad no significant effect. Our study demonstrates similarities and differences in habitat use of two important herbivores of the Northern temperate forests. We propose that managers establish ‘decoy’ sites for deer: areas with a high proportion of ground vegetation and young trees of lower forestry value. This will serve to divert deer from valuable trees and thereby enhance biodiversity. These open stands could be interspersed with dense islands of young coniferous trees to offer shelter and should be distant to frequently used pathways. Mineral licks may help enhance use of these sites. Providing an attractive resource for both species of cervids is the best way to manage large herbivores in economically valuable forests.

Habitat destruction is one of the major causes of large carnivore decline worldwide. The present study assesses the ecological and anthropogenic determinants of site use by leopard and lion in the Gir forest. Data on leopard and lion site use was collected through camera traps and modeled using prey availability, proximity to water, woody cover, proximity to human habitation and grazing intensity as the predictor variable. A generalized linear model was used to find the effect of a predictor variable on leopard and lion site use intensity. Leopard site use intensity was positively associated with chital, nilgai, and sambar availability, and grazing intensity while negatively associated with proximity to water. Lion site use intensity was positively associated with nilgai availability, woody cover and grazing intensity while negatively associated with sambar availability, and proximity to water. The present study indicated that habitat might have a substantial role in determining prey–predator spatial relationships. Also, humans provide resources such as artificial water holes could potentially affect the distribution of both the predators in our study area. The present study could be useful while making management decisions in Gir.

Resource selection studies are commonly used to assess the landscape features that animals select or avoid in their environment. Selection for certain landscape features and landcover types may vary by sex and reproductive status of an individual, and habitat selection studies should incorporate these factors. Cougars Puma concolor are a wide-ranging species that live in a diversity of habitats with varying levels of human disturbance. Geographic positioning satellite telemetry collars were deployed on 55 males, single females and females with kittens. We used a two-stage resource selection function to assess the seasonal habitat characteristics used by adult cougars in west-central, Alberta, Canada, near the northern extent of the species range, from 2016 to 2018. A latent selection difference function was used to compare differences in habitat selction between groups. All groups selected for similar habitat types including edge habitat, close proximity to water, sloped terrain, forested habitat and avoided roads. During the summer, close proximity to water and wetland land cover were among the most selected features for all groups. Forest and edge habitats also were important for single females and males. During the winter, forested habitat was one of the most important covariates for all groups along with close proximity to water, edge habitat and slope for single females and males. Selection for slope and avoidance of open agricultural land were among the most important for females with kittens. Our results provide insights into those landscape variables that are important for cougars at the northern extent of their geographical range.

Concentrated resources or hotspots, within an individual's usual home range may be strong determinates of movement behavior. We evaluated the patterns of mineral lick use by a population of mountain goats Oreamnos americanus displaying high site fidelity at two mineral licks along the Trans-Canada Highway in the Rocky Mountains, British Columbia, Canada. Access to these mineral licks was characterized by deliberate and repetitive movements into marginal habitat. We describe the patterns of mineral lick use over decadal, seasonal and daily periods by using dendrochronological analysis of trampling scars along mountain goat trails, movements determined from GPS collar locations, and camera traps placed along trails and at mineral licks, respectively. Our findings suggest that mountain goats have strong trans-generational behavioral traditions and that they predictably access mineral licks using the same trails, seasons and daily patterns. Differences in the patterns of mineral lick visitation between males and females may be related to reproductive and nutritional status, while their nocturnal use appears to be a response to disturbance at the mineral licks. Understanding how animals adjust their behavior in response to highly localized resource hotspots outside their usual home range can provide valuable information for the management of these critical habitat features and the wider conservation of mountain goat populations.

Knowledge of population trends is of key importance for sustainable management of wildlife and finding reliable and cost–effective monitoring methods is therefore of great interest. In two populations of Alpine chamois Rupicapra rupicapra, we collected data on mortality from 12 424 individuals hunted or found dead and population size data based on ground counts over a period of 28 years. Our study had three aims: 1) we investigated if changes in population size obtained with a simple deterministic population reconstruction (DPR) approach using hunting and natural mortality covary with population size estimates obtained from ground count data. 2) We investigated if the performance of DPR is affected by the removal of natural mortality data. 3) We assessed how many years of mortality data are needed to obtain consistent population trends using DPR. Our results suggested that 1) population abundance from mortality data using DPR significantly and positively correlated with population abundance obtained with ground counts. 2) DPR without natural mortality data performed similarly as compared to DPR using full data (hunting and natural mortality). 3) Consistent estimates of population trends can be obtained with ≥10 years of mortality data, however, this time span was influenced by the mean age at death, which in turn was affected by the local hunting regime. Our results suggest that DPR and ground counts perform similarly for the estimation of temporal trends in Alpine chamois abundance. The consistence of ground counts and DPR supports the use of these methods as reliable tools for tracking abundance of chamois populations over time. However, the reliability of abundance estimates using DPR may vary between populations and the influence of different hunting regimes must be considered for the correct interpretation of results.

Indirect measures of abundance are essential for evaluating temporal and spatial trends in animal populations under hunting pressure and hence for evaluating the impact of hunting on the population stock. Recently, harvest-based estimation has received attention due to its capacity to estimate population size, hunting mortality and population growth parameters based on the responses of indirect measures to hunting pressure. Although harvest size is a widely used statistic for game animals and its validity as an indirect measure of abundance has been intensively investigated, its applicability to harvest-based estimation has rarely been studied. In this study, we applied a simulation approach to examine the accuracy of harvest-based estimation when harvest size is used as an indirect measure under different temporal patterns of capture effort (constant, increasing and decreasing). We simulated a dataset using a Poisson-binomial surplus-production model that explicitly considers the effect of capture effort on harvest size and tested the estimation accuracy and model identifiability (i.e. whether there is sufficient statistical information in a dataset to specify model parameters) when harvest size is used as an indirect measure. We then compared the estimates with those of the original Poisson-binomial surplus-production model. We found that estimates of the population size and intrinsic growth rate were severely biased when the temporal heterogeneity in capture effort was large. When capture effort was constant and harvest size was thus proportional to the population size, on average, only 10% of iterations were identifiable. The use of harvest size as a population index in harvest-based estimation can result in seriously biased estimates of population size and growth rate or low identifiability of parameters. Our results highlight the importance of monitoring capture effort and unbiased population indices, in addition to harvest sizes, to evaluate the population status of game animals by harvest-based estimation.

The endangered Galápagos sea lion lives among a rapidly growing human population, and conflicts between humans and sea lions are increasing. Protection of this fragile species requires a better understanding of how anthropogenic activity affects its health and survival. In this study, we engaged a group of local students in a community science project to conduct long-term observations of the effects of human disturbance on sea lion behavior. We compared three types of behavior – reaction to human approach, vocalizations and group size – across four different haul-out sites which varied in their levels of human disturbance. We found that sea lions respond less aggressively to humans on beaches that are more disturbed. This may be because sea lions acclimate to human disturbance or because sea lions with a low tolerance for humans avoid disturbed sites. We also found that aggressive vocalizations between sea lions increase as sea lion group size increases, though group size was not linked to human disturbance. We did not quantify stress levels, but aggressive behavior often indicates elevated stress levels, which are energetically costly and can impair immune function. Our results suggest that conservation efforts should focus on limiting human–sea lion interactions and increasing the number and quality of available haul-out sites.