We have focused our study on the concentrations of essential heavy metals (Zn, Cu and Mn) and non-essential trace metals (Pb, Cd and Cr) in the livers of birds from Eastern Poland. The largest mean amount of Zn - as much as 279 mg/kg dry mass (d.m.) - was found in mute swans. However, only in one of the analysed buzzard specimens the concentration of Zn, found to be 664 mg/kg d.m., exceeded the level indicative of poisoning for this element. Birds specializing in catching rodents accumulated Mn in their livers in a very narrow range of concentrations, around 5.0 mg/kg d.m. on average. The range of mean Mn concentrations (around 6.5 mg/kg d.m.) was also found to be narrow for piscivorous birds. The highest mean levels of Pb were found in mute swans (2.7 mg/kg d.m.), and the highest levels of Cd (2.0 mg/kg d.m.) for rooks. Concentrations of total Cr above detection level were found in 22 specimens (53.7%), and concentration values were highest for rooks. Analyses showed that the concentrations of biogenic elements did not exceed the levels indicative of poisoning (except in one specimen). The study demonstrated that lead shots remain a hazard to water ecosystems. Pb, Cd and Cr levels in the livers of omnivorous and piscivorous species indicate the permanent presence of these elements in the environment and may confirm the thesis about the growing role of electronic waste, including metallic e-waste, in the emission of the total amount of contamination with these elements

The frequency and species diversity of keratinophilic fungi in 38 nests of nine species of wetland birds were examined. Nine species of geophilic dermatophytes and 13 <em>Chrysosporium</em> species were recorded. <em>Ch. keratinophilum</em>, which together with its teleomorph (<em>Aphanoascus fulvescens</em>) represented 53% of the keratinolytic mycobiota of the nests, was the most frequently observed species. <em>Chrysosporium tropicum, Trichophyton terrestre</em> and <em>Microsporum gypseum</em> populations were less widespread. The distribution of individual populations was not uniform and depended on physical and chemical properties of the nests (humidity, pH).

The impact of social factors on the improvement of hunting skills of juvenile marsh harriers during their first autumnal migration were studied in SE Poland. While foraging with adult birds, juveniles performed more dives on prey both in terms of number of trials and rates. Hunting sessions of juveniles were more efficient in the presence of adults than in the absence of adults. Juveniles hunting with adults and other juveniles could select adequate habitat patches in which access to prey is easier. The role of vertical and horizontal transmission of information in the development of hunting skills in juvenile marsh harrier were confirmed because faster development of hunting ability was achieved in the social hunting after the end of their postfledging dependency period.

A study was performed on the numbers and species diversity of thermophilic fungi (growing at 45 °C in vitro) in 38 nests of 9 species of wetland birds, taking into account the physicochemical properties of the nests and the bird species. It was found that in nests with the maximum weight (nests of Mute Swan), the number and diversity of thermophilic fungi were significantly greater than in other nests, with lower weight. The diversity of the thermophilic biota was positively correlated with the individual mass of bird and with the level of phosphorus in the nests. The dominant species within the mycobiota under study was Aspergillus fumigatus which inhabited 95% of the nests under study, with average frequency of ca. 650 cfu g(-1) of dry mass of the nest material. In a majority of the nests studied (nests of 7 bird species), the share of A. fumigatus exceeded 50% of the total fungi growing at 45 °C. Significantly higher frequencies of the fungal species were characteristic of the nests of small and medium-sized piscivorous species, compared with the other bird species. The number of A. fumigatus increased with increase in the moisture level of the nests, whereas the frequency of occurrence of that opportunistic pathogen, opposite to the general frequency of thermophilic mycobiota, was negatively correlated with the level of phosphorus in the nest material, and with the body mass and length of the birds. The authors indicate the causes of varied growth of thermophilic fungi in nests of wetland birds and, in particular, present a discussion of the causes of accumulation of A. fumigatus, the related threats to the birds, and its role as a source of transmission in the epidemiological chain of aspergillosis.

Globally, wildlife is affected by unprecedented changes related to the COVID-19 pandemic. In this paper, the lockdown effect on the traffic-related mortality in hedgehogs in an urban area was studied. Comparing the pre-pandemic (2018 and 2019) and pandemic (2020) years, we showed that hedgehog roadkill levels during the lockdown period were over 50% lower (which means a decrease greater than the decrease in road traffic in the same period measured by the number of accidents or the average number of vehicles per day). Based on literature data, we showed that this may mean at least tens of thousands of hedgehogs have survived on a national scale. We report the need to start intensive research on the possible demographic and genetic effects of this unique phenomenon. We also ask how stable the effect of the COVID-19 pandemic will be on wildlife and whether the lockdown (which is an anthropause) may reverse the negative trends in the decline in the number of wild species, including hedgehogs.