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Fascination with animals and their behaviour is one the most prominent patterns persisting in all human cultures. During the last decades, however, technological development and public access to the Internet have increased the speed and the extent of information sharing at an unprecedented rate, in some cases even challenging the traditional methods used in science. In order to understand the extent of this influence, we focused on the behaviour of shrikes. Shrikes are an enigmatic group of songbirds with a unique behaviour of impaling prey. We employed an extensive Internet search on YouTube (YT), a very popular and increasingly important source of information worldwide, for videos recording shrikes. Our analyses revealed that the number of shrike videos on YT is strongly positively correlated with classical knowledge on shrikes from books and scientific articles. Our results also suggest that in some cases YT may provide an alternative source of information on shrike ecology and behaviour. YT videos may thus provide new insights into the study of certain species or subjects and help identify gaps in ecological studies, especially in poorly studied species. Electronic supplementary material The online version of this article (doi:10.1007/s00114-017-1470-8) contains supplementary material, which is available to authorized users.

Invasive species have a substantial influence on the environment, especially through competition with local, native species. In Europe, oak trees provide a good example of competition between species native to the region and species introduced from elsewhere in the Northern Hemisphere. When introduced species start to have a negative impact they are considered invasive. Here we focus on the seed dispersal of a native (Pedunculate Oak Quercus robur) compared to an introduced oak (Northern Red Oak Quercus rubra) where the main animal disperser of acorns is the European Jay Garrulus glandarius. The study was conducted in two forests in western Poland by placing acorns of both species in trays and monitoring their removal, and by recording establishing oaks on transects. We showed that jays were about twice as likely to harvest the acorns of the native oak compared to those of the introduced oak. Nevertheless, the extent of dispersal by jays of the acorns of the introduced oak species will facilitate colonization of new areas. Establishment of young trees of the introduced species was much greater than that of the native species despite the former having lower dispersal and being considerably underrepresented in the canopy. Thus, consequences for patterns of oak survival and forest development seem very likely.

Seeds are under strong pressure from seed predators. Therefore any physical seed trait increasing the chances of the seed's survival should undergo positive selection. Seed color polymorphism, varying from pale to dark seeds, occurs in Scots pine (Pinus sylvestris), a keystone species of coniferous forests in Eurasia. This phenomenon can be explained by the production of large quantities of empty, always pale colored, seeds, with the opportunity for mimicry of these worthless seeds to avoid predation. Here, we investigated how the color of empty seeds may influence the foraging choices of the most common visual seed predator in temperate forests, the Chaffinch (Fringilla coelebs). We show, from field experiments, that different colored seed had different probabilities of predation by the chaffinch, and that predation was highest for dark seeds and lowest for pale empty seeds. Thus, the occurrence of empty seeds might benefit full seeds which mimic their coloration, even for those which are highly visible on the ground. In conclusion, the study demonstrated that mimicry by seeds of the color of the ground did not improve their survival but the production of pale full seeds resembling empty seeds did. This contradicts previous results and indicates that color polymorphism may reduce the predation rate by birds.

Urban areas attract birds during the winter when cities provide a predictable source of food and relatively stable weather conditions. However, many other factors determine the occurrence of birds in cities. This study analysed the relationship between corvids wintering in the city of Poznań, in western Poland and habitat features. Each of 32 research site was investigated three times. The most abundant species was the rook (mean = 17.4 individuals/site); the most frequent was the Eurasian magpie (88% of all sites). To determine variables that influence the abundance of birds, a set of generalised linear models was created, with model averaging being selected for each species. The abundance of hooded crows was positively influenced by surface of parks, water and by the length of tram tracks. The number of rooks was positively linked with the number of walnut trees, garbage cans and the surface of the water and negatively linked with the length of watercourses. Jackdaw was affected positively by the number of garbage cans, the surface of the water and negatively by the cover of trees. The number of magpies was associated with the number of walnut trees, garbage cans and negatively influenced by the surface of trees. None of the investigated habitat variables significantly affected the abundance of European jay. We also found a positive correlation between the abundances of hooded crow, rook, jackdaw and magpie. The results indicate that corvids wintering in urban ecosystems exhibit selectivity toward specific habitat features and that preferences differ among the studied species.