Przemysław Chylarecki

Conservation policies increasingly rely on multispecies indicators to track biodiversity change and evaluate conservation measures, yet the commonly used two-step indicators weight species equally and underestimate uncertainty. We propose a multispecies index estimated in a single step directly from raw site-level counts, transferable to any monitoring programme based on such data. We demonstrate it using 25 years (2000–2024) of Common Breeding Bird Survey data from Poland, comparing three species groups (all common, farmland and forest) inside and outside Natura 2000 Special Protection Areas (PAs), which cover 16% of the country. Abundance of all common species was 11% higher inside PAs over the study period, while farmland species were 11% less and forest species 33% more numerous inside PAs. During the first years of the study, bird numbers increased both inside and outside PAs, but faster within them (e.g. 5.4% vs 3.0% per year for all common species). In all groups, the trend reversed to decline or stabilisation earlier inside PAs: by 4.3 years in all common species, 6.9 years in forest birds and 2.0 years (not significant) in farmland birds. After this changepoint, rates of change stabilised inside PAs, while declines continued outside. These patterns suggest that high-quality habitats both reveal population change earlier and buffer subsequent declines. Protected areas are therefore not only important for conservation but also valuable as early indicators of population change, and indicators reported separately for protected areas could strengthen the monitoring of EU biodiversity targets.

The impact of wind power installations on the natural environment, including forest ecosystems, has been investigated for a considerable period of time. Based on currently available data, the authors conclude that operating wind turbines within forest areas poses a significant threat to forest environments, particularly to flying animals, including legally protected species. The reviewed studies indicate that wind power plants situated in forests have substantial potential to affect both the natural environment and the landscape. It has been found that siting wind farms in forested areas, which are typically characterised by high biodiversity, further increases the environmental risks commonly associated with such installations. Locating wind energy facilities in forests has also generated social controversy in countries where such investments are being implemented, primarily in Germany and the Scandinavian countries, and is frequently opposed by environmental protection organisations and scientific experts. In their conclusions, the authors state that although lower procedural costs and the anticipated greater ease of obtaining permits for publicly owned land may encourage investors to plan such developments in forest areas, the confirmed higher environmental costs – compared with constructing wind turbines in open landscapes – necessitate a critical assessment of the justification for such investments.

Knowledge of species distributions is essential for informing policies on nature conservation and restoration. However, updating them on a regular basis and doing so in a harmonized manner at the international level is difficult. The European Bird Census Council integrated national monitoring data covering 5 years to update farmland bird distributions and assessed how they changed. We used these data on 50 farmland bird species to generate 10×10 km maps showing their probability of occurrence from 2018 to 2022. We produced these maps with weighted ensemble species distribution models. We also developed models for the previous 5 years and plotted the differences in probabilities of occurrence per 10 × 10‐km area between the two periods as calibrated change maps. We evaluated model performance at continental and regional levels and interpreted changes in probability of occurrence in relation to known abundance trends. Models showed good predictive performance (mean AUC ≈ 0.84; mean squared error ≈ 0.13). Change estimates were reliable for 43 species (high accuracy, low bias), and distribution changes were positively correlated with independent abundance trends (Pearson's r ≈ 0.50). Thus, the distribution maps for the two periods accurately captured species’ distribution patterns and their temporal changes for all species at the European scale and for the majority of species in all regions except southeastern Europe. Among the 43 species with reliable estimates, predicted occurrences declined for 33 species, increased for nine, and were the same for one species. For most species, the direction of change in distribution was consistent with changes in species overall abundance in the same period, except for four species. Overall, our results indicated a recent contraction of farmland bird distributions in Europe, highlighting the strong capacity of existing bird monitoring networks to provide continent‐wide species maps that can be updated regularly.

Competition plays a key role in shaping predator communities, but carrion abundance can alter these interactions. We investigated interactions between grey wolves (Canis lupus), an apex predator and golden jackals (Canis aureus), an opportunistic mesocarnivore, in carrion-rich regions of Greece, where livestock carcasses are frequently dumped by farmers. Using unmanned aerial vehicles with thermal imaging, handheld thermal cameras and camera traps, we recorded nearly 1100 wolf and over 9000 jackal sightings across landscapes. Our analyses showed that jackals fed and rested more often near abundant food, with larger carcasses leading to prolonged interactions. There was a strong positive relationship between carcass biomass and jackal group size, highly moderated by season, facilitating joint feeding and accelerating carrion consumption. Wolves feeding alongside jackals were mostly solitary, while jackals formed groups of around five, likely benefiting from reduced risk and greater feeding opportunities. Larger carcasses attracted more interactions between species, supporting our hypothesis that ample food supply reduces direct competition and fosters greater tolerance. However, competition persisted, as we recorded multiple cases of jackal food theft and a single fatal wolf–jackal encounter. These findings challenge rigid predator hierarchies, highlighting how resource abundance promotes coexistence and underscoring the need for effective wildlife management in food-abundant environments.

Previous research strongly associates the body size of poikilotherms with variations in environmental temperature. To investigate this relationship in Meloidogyne hapla , eggs were incubated at 5, 10, 20 (control), 30, 35, and 40°C for durations of 1, 2, 8, or 24 h (10 eggs per Petri dish × 3 dishes, n = 30 eggs per treatment). Following treatment, eggs were maintained at 20°C until hatching into second-stage juveniles (J2), at which point body size traits including body length, width, and mass were evaluated. The findings demonstrate that both incubation temperature and duration are strongly linked to those body size traits of emergent J2. Notably, an incubation temperature of 40°C was consistently associated with a complete absence of embryogenesis across all durations. The most pronounced size reductions occurred at 35°C, corresponding to the minimum J2 dimensions recorded, where length, width, and mass were lower by 5,5%, 11,5%, and 25.4% relative to the control, respectively. Conversely, maximum body length aligned with the 30°C treatment (a 0.85% increase over the control), whereas peak values for width and mass coincided with the 20°C control temperature. These data indicate that while successful egg development aligns with the 20 to 30°C thermal range, morphometric trends vary by specific trait (length vs mass/width), a pattern that corresponds with established literature on the developmental range of M. hapla eggs.

The impact of wind power installations on the natural environment, including forest ecosystems, has been investigated for a considerable period of time. Based on currently available data, the authors conclude that operating wind turbines within forest areas poses a significant threat to forest environments, particularly to flying animals, including legally protected species. The reviewed studies indicate that wind power plants situated in forests have substantial potential to affect both the natural environment and the landscape. It has been found that siting wind farms in forested areas, which are typically characterised by high biodiversity, further increases the environmental risks commonly associated with such installations. Locating wind energy facilities in forests has also generated social controversy in countries where such investments are being implemented, primarily in Germany and the Scandinavian countries, and is frequently opposed by environmental protection organisations and scientific experts. In their conclusions, the authors state that although lower procedural costs and the anticipated greater ease of obtaining permits for publicly owned land may encourage investors to plan such developments in forest areas, the confirmed higher environmental costs – compared with constructing wind turbines in open landscapes – necessitate a critical assessment of the justification for such investments.

Long-term monitoring is essential to address ongoing biodiversity loss. This study provides a comprehensive summary of the population trends of common breeding birds in Poland based on 25 years of data (2000–2024) from Common Breeding Bird Survey (CBBS). The dataset comprises 2.3 million observations of birds from 29,000 field surveys. Population trends were calculated for 124 bird species using generalized estimating equation models (GEE), analysed for two time periods: the whole study period (2000–2024) and the most recent 12 years (2013–2024). Trends varied widely among species, ranging from an 82% decline to a 579% increase, indicating that in extreme cases populations changed by up to factor of six over 25 years. Over the whole study period increases were more frequent than declines, however, in the last 12 years we found a shift towards declines. Multi-species indicators reflected contrasting habitat-specific patterns, with a 20.4% decline in the Farmland Bird Index and a 30.8% increase in the Forest Bird Index. These patterns were confirmed by trait-based analyses, which revealed that the most negative trends were recorded for farmland and wetland birds (the latter did not differ significantly from farmland species), while increases were found for woodland birds. Population changes were also linked to migration strategy, with the strongest declines observed among long-distance migrants. There was also a significant positive correlation between trends and body mass, as well as between trends and temperature preference, indicating that large-bodied and warm-dwelling species had more positive population dynamics. The optimal model explained 25% of the variation in long-term species trends, suggesting that additional drivers likely contributed to observed population changes. Overall, these results revealed substantial variability in population trends of common birds in Poland and highlighted the importance of continued long-term monitoring for understanding biodiversity change.

Intraspecific variation in nest size received considerable attention in the last two decades. A number of studies of small passerines found that nests built at lower ambient temperatures were larger than those built at higher temperatures. As larger nests, although costly, provide a better thermal environment for eggs and small nestlings, this has been interpreted as adaptive phenotypic plasticity. Yet, a comparable number of studies failed to confirm the relationship between temperature and nest size. We used data from a nest box population of Great Tits Parus major breeding in central Poland to test the possible effect of temperature on nest size built by females with multiple nests measured during a 3-year study. Using the sliding window approach, we identified the exact time window for which the given weather variable best explained the variation in the nest trait, in addition to that already explained by study year, clutch type (first or second) and female identity. For each nest trait and weather variable, we tested all possible time windows over a 30-day period prior to the first egg laying date (FED). We found that for the studied Great Tit population time windows of sensitivity of nest traits to temperature opened 19–24 days before FED and closed 6–15 days before FED. Maximum daily temperature was consistently a better predictor of nest size characteristics than either minimum daily temperature or mean daily temperature. For precipitation, the only significant sensitivity window opened 27 days before FED and closed 3 days before FED. Thus, temperature sensitivity time windows opened 5–10 days before the start of nest building and lasted no longer than halfway through the building period. Temperature effects were only detectable after accounting for the strong effects of female identity on nest size. The failure to observe temperature effects on nest size in some previous studies may be explained by considering temperatures during nest building rather than some time earlier, or by ignoring persistent female effects on nest size in the analyses.

In bird species with a lek mating system, male mating success is usually correlated with time spent at the lek, suggesting strong selection for lek attendance. We studied the lekking of Great Snipe Gallinago media males over 5 breeding seasons in Poland and found that, in apparent contradiction, 75% of males changed leks, often several times, within a single breeding season. GPS-tagged individuals tracked for an average of 31 days visited up to 9 different leks, often visiting 2–3 leks in quick succession within a few hours. Transitions between leks were entirely nocturnal, peaking before midnight. The majority of males that changed leks moved to sites within 50 km of the original lek, but 10% of males dispersed more than 100 km. Lek-switching males typically made several transitions between leks during the breeding season (median = 4), with most mobile birds changing display sites more than 20 times. Lek-switching probabilities showed seasonal variation, with no males changing leks early in the breeding season and frequent changes thereafter. The daily probability of lek change showed large inter-individual variation, allowing two groups of males to be distinguished, those who never or rarely changed leks (mean daily probability of lek change 0.02) and those who frequently changed leks (mean daily probability of lek change 0.23). This type of heterogeneity in male lekking behaviour is consistent with the hot-shot scenario of lek evolution. Here, lekking males with low mating chances should benefit from lek-switching — in contrast to top-ranking males — because changing display site may allow them to find leks with higher mating chances. Furthermore, regardless of its immediate success or failure, lek-switching can be seen as a form of prospecting behaviour that will pay off in future breeding seasons. Consistent with this, many of our lek-switching males moved in a way that suggests informed dispersal. The prevalence of intraseasonal lek switching in different Great Snipe populations across Europe should be assessed using the modern tracking devices, as this behaviour is likely to be much more widespread than reported in many previous studies.