Fundamental principles regarding urban biodiversity are based on studies conducted in large cities. However we cannot know whether the same phenomena occur in smaller cities or how small cities affect biodiversity. Small cities are an inherent element of urbanization and in the future, most global urban growth is expected to take place in small and medium-sized cities. Understanding the effects of small cities on biodiversity will be an important aspect in planning urban land expansion. Our study examined the effects of a small city on communities of small ground-dwelling mammals on 41 sites arranged in a four step gradient of urbanization. In 6700 trap-days, we caught 2333 individuals comprising 15 species. In the downtown area the same phenomena as those described for large cities were observed: a reduction in species richness and diversity, a decline in the abundance of urban sensitive species and an increase in synurbic species. However, in contrast to large city studies, green areas outside the downtown area did not differ from rural sites in small mammal population parameters. This phenomenon of relatively unchanged fauna outside the downtown area shows that small cities have the potential to maintain a high level of diversity of small ground-dwelling mammals if appropriate planning of further building expansion is implemented. More studies of small cities are needed to better assess their impact on biodiversity. This knowledge can then be applied in better planning for urban wildlife. Generalizations based solely on large city studies are inadequate and may lead to incomplete or inappropriate conservation strategies for small cities.

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.

As a top predator, the white-tailed eagle (Haliaeetus albicilla) may serve as a good indicator species, providing information about the bioavailability of contaminants and their transfer within the food chain. In this study, we aimed to determine the common sources of origin of 17 metals and other elements in the liver of white-tailed eagles, and to compare the variations in their hepatic concentrations by age (adults vs immatures) and sex (males vs females) in groups of white-tailed eagles wintering in Eastern Poland. The element concentrations followed the pattern of S > K > Na > Fe > Mg > Ca > Zn > Cu > Mn > Se > Pb > Hg > Cd > Cr > Sr > V > Sc. We found significant age-related differences in the hepatic concentrations of some of the elements. Adults showed higher concentrations of Pb, Cd, Ca, Fe, and Zn and lower concentrations of Cu and Se than immatures. These differences may be explained by age-related differences in wintering strategy (adults are sedentary, and immatures are migratory) and hunting skills (adults are more successful when hunting for agile prey). Our study indicates that ingested Pb ammunition poses a serious threat to the health and lives of white-tailed eagles in Poland (32% of the studied individuals had acute lead poisoning). Our study also indicates a serious need for banning the use of lead hunting ammunition in the parts of Europe (including Poland) where it is still allowed.