Krzysztof Schmidt

Daily activity budgets reflect how animals balance internal physiological demands with external environmental pressures. We analyzed 14 037 camera‐trap records from 12 mammal species in the Venezuelan Llanos to evaluate the effects of foraging strategy (faunivore versus herbivore), season, and body mass on daily activity duration, to describe diel activity patterns, and to examine temporal overlap among species. Faunivores were active for nearly twice as long as herbivores (mean 12.1 versus 7.2 hours day ⁻¹ ), and trophic guild was the only significant predictor of daily activity duration. Activity duration did not differ significantly between wet and dry season at the community level, and body mass showed no significant effect once trophic guild was accounted for. Faunivores were primarily nocturnal, while most herbivores were diurnal. Although season had no general effect, some herbivores showed marked seasonal differences: eastern cottontail rabbit and white‐tailed deer were more active in the wet season, whereas capybara was more active in the dry season. Jaguar and puma showed very high temporal overlap, providing no evidence of temporal segregation between these two large felids, and overlap between large carnivores and their principal prey was only moderate. These results identify trophic guild as the strongest predictor of daily activity duration in this mammal assemblage and suggest that seasonal responses are species‐specific rather than general across herbivores.

As wolves recolonize human-dominated landscapes across Europe, managing risks amidst increasing reports of close encounters becomes essential. We present a retrospective, multidisciplinary analysis of a case from Poland involving the removal of a wolf for bold behavior toward humans. Our findings suggest that the wolf’s unusual actions were influenced by prior captivity exposure, as evidenced by a dietary shift from domestic to wild meats and genetic connections to a region known for captive rearing. Camera-trap data showed that during the wolf’s presence, local pack activity peaked, with a notable rise in single-wolf detections, contrasting with patterns during a control season without the case wolf. Although the threat to human safety was minimal, a public survey highlighted concerns about wolf-dog interactions. We advise evaluating bold wolves on a case-by-case basis, incorporating ecological and social evidence into investigations, and emphasizing human responsibility in preventing undesirable wolf behaviors.

Understanding the genetic basis of adaptation is essential for reconstructing evolutionary processes, and this can be accomplished particularly by studying closely related species occupying diverse ecological niches. In this study, we performed genome-wide scans for recent selective sweeps in the four extant species of the Lynx genus—Lynx canadensis (Canada lynx), Lynx rufus (bobcat), Lynx lynx (Eurasian lynx), and Lynx pardinus (Iberian lynx)—using a composite likelihood ratio test based on genotype frequency spectrum. Analyzing whole-genome sequences from 80 individuals, we identified species-specific selective sweeps and conducted functional enrichment analyses to explore biological processes under selection. Results revealed distinct adaptive mechanisms shaped by ecological specialization and demographic histories of different species. In Canada lynx, enriched functions include olfactory signaling and pigmentation-related processes; the Eurasian lynx showed signals related to cardiac and neural development; the Iberian lynx exhibited enrichment in immune-related pathways, potentially reflecting pathogen-mediated selection under strong genetic drift; and the bobcat displayed functional signals in reproductive and metabolic regulation. Our study revealed the species-specific nature of recent signatures of ecological differentiation in the genomes of closely related species of the genus Lynx, with minimal overlap, illustrating their diverse evolutionary trajectories and shedding light into the mechanism of adaptation among highly specialized carnivores.

Extra-territorial mating excursions (i.e. short-term movements beyond established home ranges to seek mating opportunities) represent an underexplored reproductive strategy in felids. Using telemetry data from 125 Eurasian lynx (172 lynx-years, 1995–2023) across Europe, we investigated sex-specific spatio-temporal patterns and drivers of these excursions during the mating season. Overall, 33% of males and 11% of females undertook excursions, with males having higher rates than females. Male excursions mostly occurred in March, coinciding with the peak of the conception period, while females tended to undertake excursions either before or after this peak. The median Euclidean distance travelled beyond the home range was 6.8 km for males and 2.6 km for females, with corresponding median durations of 119 h and 85 h, respectively. Translocated individuals exhibited higher excursion rates than those in established populations, suggesting mate-searching in novel environments. We found no evidence that human influences affected excursion rates or distances. Our findings highlight a mating tactic that is often overlooked and provide new insight into sex-specific and context-dependent movement strategies in Eurasian lynx. By linking extra-territorial excursions to reproduction patterns, our study informs future research on mate-searching behaviour in felids and offers implications for conservation planning, particularly in isolated or reintroduced populations.

Many diseases commonly found in domestic cats may represent potential threats to wild cats. This study investigates the prevalence of selected viral pathogens in the Eurasian lynx (Lynx lynx) and European wildcat (Felis silvestris) in Poland, both being strictly-protected species vulnerable to environmental pressures. A total of 20 Eurasian lynx and five wildcats were subjected to serological and molecular analyses (ELISA and real-time PCR) aimed at confirming the presence of antibodies and genetic material for feline leukemia virus (FeLV), feline immunodeficiency virus (FIV), feline coronavirus (FCoV), feline calicivirus (FCV), feline herpesvirus (FHV), and feline panleukopenia virus (FPV). Antibodies were most frequently detected against FCV (32%), and FHV (32%), FCoV (23.1%), and FeLV (16%). No FIV and FPV antibodies were detected. Viral genetic material was confirmed in four animals, with FCV being most prevalent (9.1%), followed by FeLV and FHV (each 4.5%). Statistically significant associations were observed between the presence of FCV and FHV. These results suggest that viral infections may play a role in limiting wild felid populations in Central Europe. Continued surveillance is crucial to inform conservation efforts and assess long-term health risks.

Survival and cause‐specific mortality rates are vital for evidence‐based population forecasting and conservation, particularly for large carnivores, whose populations are often vulnerable to human‐caused mortalities. It is therefore important to know the relationship between anthropogenic and natural mortality causes to evaluate whether they are additive or compensatory. Further, the relation between survival and environmental covariates could reveal whether specific landscape characteristics influence demographic performance. We used telemetry data on 681 Eurasian lynx ( Lynx lynx ), a model apex predator with large spatial requirements, that were tracked across their European distribution. Through time‐to‐event analyses, we sought to determine the variables associated with differences in their survival. Illegal killing was the main cause of mortality (33.8%), and mortality rates were similar in protected and hunted populations (8.6% and 7.0% per year, respectively). Survival varied greatly across populations (70–95% per year). Across all study sites, higher hunting and anthropogenic mortality rates were partially compensated by lower rates of other mortality causes but not by natural mortality alone. Variation in survival depended on sex (female survival was 1.5 times greater than male survival) and seasonality (highest risk during hunting season and winter), and lower survival rates were correlated with higher human modification of landscapes at both coarse (home range composition) and fine (habitat use within home range) scales. Some variation in survival was driven by unobserved factors, which, given the high rates of human‐caused mortalities, including illegal killing, are of foremost concern. Due to the low natural mortality rates in protected and hunted populations, we conclude that anthropogenic causes of mortality are likely close to additive, such that maintaining or increasing refuge habitat with little human disturbance is critical to lynx conservation.

Local adaptations to the environment are an important aspect of the diversity of a species and their discovery, description and quantification has important implications for the fields of taxonomy, evolutionary and conservation biology. In this study, we scan genomes from several populations across the distributional range of the Eurasian lynx, with the objective of finding genomic windows under positive selection which may underlie local adaptations to different environments. A total of 394 genomic windows are found to be associated to local environmental conditions, and they are enriched for genes involved in metabolism, behaviour, synaptic organization and neural development. Adaptive genetic structure, reconstructed from SNPs in candidate windows, is considerably different than the neutral genetic structure of the species. A widespread adaptively homogeneous group is recovered occupying areas of harsher snow and temperature climatic conditions in the north‐western, central and eastern parts of the distribution. Adaptively divergent populations are recovered in the westernmost part of the range, especially within the Baltic population, but also predicted for different patches in the western and southern part of the range, associated with different snow and temperature regimes. Adaptive differentiation driven by climate does not correlate much with the subspecies taxonomic delimitations, suggesting that subspecific divergences are mostly driven by neutral processes of genetic drift and gene flow. Our results will aid the selection of source populations for assisted gene flow or genetic rescue programs by identifying what climatic patterns to look for as predictors of pre‐adaptation of individuals. Particularly, the Carpathian population is confirmed as the best source of individuals for the genetic rescue of the endangered, isolated and genetically eroded Balkan population. Additionally, reintroductions in central and western Europe, currently based mostly on Carpathian lynxes, could consider the Baltic population as an additional source to increase adaptive variation and likely improve adaptation to their milder climate.

Large European carnivores are generally considered forest animals. However, there are a number of interacting factors that may have different impact on the availability and suitability of habitat for individual species. Felids, because of their stalking hunting mode, are habitat specialists requiring a heterogeneous environment, making them specifically vulnerable to habitat disturbance. The Eurasian lynx (Lynx lynx), despite protection in many European countries, has a surprisingly limited range. To explain environmental factors that affect its distribution, we undertook habitat selection and habitat suitability analyses at the macrohabitat and microhabitat scales, based on lynx occurrence and environmental data in Poland. Since the species occurs in two populations, one of which inhabits lowland and the other mountainous area, we modelled habitat suitability separately in both areas and then extrapolated it for the whole country scale. The lynx selected forests with medium undergrowth density in the lowlands and highly rugged terrain in the mountain areas—a proxy of stalking cover. Habitat suitability modelling performed at the macrohabitat scale identified around 110 000 km² of habitat available from which 55 700 km² was classified as high quality including large tracts of forests in western Poland that are beyond the natural range of the lynx. However, the microhabitat model built by including stalking cover variables, decreased high‐quality habitats to only 33% of the area designated at the macrohabitat scale. This model is largely consistent with the current distribution of lynx in Poland. This suggests that the simplified internal structure of forests (lacking understory cover) may act as a hindrance to increasing the distribution of lynx populations and helps to explain its limited range in the Central European lowlands. This research suggests that the microhabitat structure may play the crucial role in the effective conservation of the Eurasian lynx.

Most large felids are classified as solitary species, with only lions (Panthera leo) and cheetahs (Acinonyx jubatus) exhibiting social, collaborative behaviours. Herein, we present evidence of the formation of male coalitions by jaguars (Panthera onca), based on data from five studies conducted with camera trapping, GPS telemetry, and direct observations in the Venezuelan Llanos and Brazilian Pantanal. Out of 7062 male records obtained with camera traps or visual observations, we detected 105 cases of male-male interactions, of which we classified 18 as aggression, nine as tolerance, 70 as cooperation/coalition, and eight as unidentified. In two studies, two male jaguars formed stable coalitions lasting over 7 years each. In the Llanos, each coalition male paired and mated with several females. For male jaguar coalitions, we documented similar behaviours as recorded earlier in lions or cheetahs, which included patrolling and marking territory together, invading territories of other males, collaborative chasing and killing other jaguars, and sharing prey. However, different from lions or cheetahs, associated male jaguars spent less time together, did not cooperate with females, and did not hunt cooperatively together. Our analysis of literature suggested that male jaguar coalitions were more likely to form when females had small home range size, a proxy of females’ concentration, while in lions, the male group size was directly correlated with the female group size. Similarly, locally concentrated access to females may drive formation of male coalitions in cheetahs. We conclude that high biomass and aggregation of prey are likely drivers of sociality in felids. Significance statement: The division into social and solitary species in large felids has so far seemed unambiguous, with only lions and cheetahs classified as social species, in which male coalitions also occurred. Our data show that, under certain conditions, male coalitions may also form in jaguar populations. Factors that drive formation of male coalitions in lions and cheetahs, but not in other species of large cats, have not been clear until now. Our analyses indicate that in jaguars, lions, and cheetahs, the concentration of females likely plays the most important role. In jaguars, the probability of male coalition occurrence is highest in populations with the smallest mean female home range size (and thus likely high local density of females), while in lions, male group size is most strongly correlated with female group size.