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Background Urban environments exert strong pressures on animal behavior, leading to altered fear responses to humans. Species with a longer history of urban presence and greater tolerance to urban environments are expected to show reduced fear responses towards humans. Here, we examined whether avian flight initiation distance (a proxy of fear)—the distance at which a bird flees from an approaching human—is associated with a species’ timing of urban colonization (i.e., when it has started to breed in urban areas) and with present-day urban tolerance (i.e., how common it is in the city). Unlike previous studies which paired avian fear responses and urbanization timing from different regions, we collected both in the same city (Prague, Czechia), minimizing regional differences in urban history and providing a more rigorous test of the link between urbanization timing and avian fear responses. Results Using standardized data from 4420 flight initiation distance observations across 68 species, we applied Bayesian phylogenetic mixed models while controlling for ecological and contextual variables. We found that species with a longer urban history (i.e., earlier timing of urban colonization) showed significantly shorter flight initiation distances, suggesting reduced fear responses. In contrast, present-day urban tolerance based on breeding commonness was not related to flight initiation distance variation. Conclusions We found that the timing of urban colonization better predicts reduced fear of humans in birds than present-day urban tolerance, emphasizing the role of long-term behavioral filtering and/or selection in shaping urban wildlife behavior. By explicitly separating urbanization time from contemporary urban commonness within a single city and analyzing individual-level fear responses, our study shows that earlier urban colonizers exhibit consistently shorter escape distances, reflecting cumulative long-term processes rather than short-term plasticity alone. These findings highlight the importance of incorporating urban colonization history into behavioral ecology and urban wildlife management frameworks.

Animals living close to human settlements more often experience disturbance, but also reduced predation risk. Because an escape response is costly, behavioural adjustments of animals in terms of increased tolerance of humans occurs and is often reported in the literature. However, most such studies have been conducted in and around long-existing cities in Europe and North America, on well-established animal populations. Here, we investigate the degree of tolerance of human disturbance across 132 bird species occurring in disturbed (small farms) and undisturbed (intact wetlands and grasslands) areas in Pantanal, Mato Grosso (Brazil), a region with only a very recent history of human-induced disturbance. We found a clear across-species trend toward higher tolerance of human disturbance in birds near farms when compared with birds in wild areas. Such a flexible and perhaps also rapid emergence of tolerance when facing small-scale and very recent human disturbance presumably involves learning and might be attributed to behavioural plasticity. The ability of birds to modify their degree of tolerance of human disturbance may play a key role in the facilitation of wildlife–human coexistence.

Most migrating birds must replenish energy reserves during migration. Food availability significantly influences migratory routes and can even force migrants to detour, but still little is known about potential co-migration between insectivorous birds and their insect prey. To address this gap, we focused on day-flying insects and the insectivorous birds migrating through the Červenohorské sedlo mountain pass, Czech Republic. During four seasons of insect and bird trapping, using Malaise trap and mist-nets, respectively, we recorded 23 094 birds of 80 species and 35 087 migrating hoverflies (Syrphidae) of 47 species. We found a strong temporal correlation between the number of migrating hoverflies and insectivorous birds crossing the mountain pass. The observed pattern suggests that a similar phenomenon may occur in lowlands, where both groups stop over before and after crossing the mountains. These stopovers may provide migratory birds with abundant and reliable food resources. We also found that hoverflies comprised 88% of the biomass of all trapped insects, making them the most abundant potential prey of migrating birds. Our results outline the co-migration of birds and hoverflies and shed light on possible predator–prey dynamics during migration.

Life-history theory predicts that current behaviour affects future reproduction, implying that animals should optimise their escape strategies to reflect fitness costs and benefits of premature escape. Both costs and benefits of escape may change temporally with important consequences for the evolution of escape strategies. Moreover, escape strategies of species may differ according to their positions on slow–fast pace of life gradients. We studied risk-taking in long-distance migratory animals, waders (Charadriiformes), during the annual cycle, i.e., breeding in Europe, stopover in the Middle East and wintering in tropical Africa. Phylogenetically informed comparative analyses revealed that risk-taking (measured as flight initiation distance, FID) changed significantly over the year, being lowest during breeding and peaking at stopover sites. Similarly, relationships between risk-taking and life-history traits changed among stages of the annual cycle. While risk-taking significantly decreased with increasing body mass during breeding, risk-taking–body mass relationship became marginally significant in winter and disappeared during migration. The positive trend of risk-taking along slow–fast pace of life gradient measured as adult survival was only found during breeding. The season-dependent relationships between risk-taking and life history traits suggest that migrating animals respond to fluctuating environments by adopting behavioural plasticity.

Detecting rare bird species is an essential aspect of ornithological culture. The pursuit of observing rare bird species is not only a key facet of birdwatching tourism but also a fascinating intersection between ornithology and sociology. However, patterns in birdwatcher gatherings around rare birds and the factors affecting these patterns in situ are largely unexplored. We directly asked 50 birdwatchers and analysed available photos to obtain details on birdwatcher gatherings at the occasion of 103 observations of 71 rare species recorded in 1996–2022 in Poland. Our analysis revealed that the number of people participating in rare bird observations was influenced by the rarity status of the species (rarer species attracted larger groups), the year (with an increase in recent years) and the interaction between these factors (there was an increasing trend for birdwatchers to ‘twitch’, that is participate in sightings of very rare bird species, in recent years). Furthermore, distance to urban centres significantly negatively affected the size of birdwatcher groups. In addition, we found that the proportion of observers who successfully saw a birding rarity at each site decreased in recent years but increased during the weekend. We also found that the proportion of women in these crowds has grown in recent years and that female birdwatchers were more willing to participate in observations of more common rarities than male birdwatchers. Our results indicate that birdwatching gatherings around bird rarities can be impacted by several factors, including the general rarity of species, year and distance to cities. A dynamic increase in the proportion of females participating in birdwatching in Poland resembles trends reported in other countries. Increased female engagement in observations of more common rarities may be potentially influenced by distinct motivations. Read the free Plain Language Summary for this article on the Journal blog. Streszczenie Wykrywanie i obserwacje rzadkich gatunków ptaków to istotne aspekty kultury ornitologicznej. Dążenie do obejrzenia rzadkich gatunków awifauny (dalej ‐ rzadkości) jest nie tylko kluczowym aspektem turystyki obserwacyjnej, ale także fascynującym połączeniem ornitologii i socjologii. Jednak wzorce przyjazdu do miejsca występowania i gromadzenia się obserwatorów ptaków wokół rzadkich gatunków i czynniki wpływające na te wzorce in situ są w dużej mierze niezbadane. Do analizy wykorzystano dane z 50 wywiadów z obserwatorami oraz poddano analizie zdjęcia zgrupowań ludzi podczas obserwacji rzadkości. Łącznie analizie poddano 103 obserwacje dotyczące 71 rzadkich gatunków odnotowanych w Polsce w latach 1996–2022. Wykazaliśmy, że na liczbę osób uczestniczących w obserwacjach rzadkości wpływał status gatunku (rzadsze taksony przyciągały większe grupy osób), rok (wzrost w ostatnich latach) oraz interakcja między tymi czynnikami (w ostatnich latach więcej osób uczestniczy w obserwacjach bardzo rzadkich gatunków ptaków). Co więcej, odległość od ośrodków miejskich znacząco negatywnie wpłynęła na wielkość grup obserwatorów ptaków. Ponadto stwierdziliśmy, że odsetek obserwatorów, którzy z powodzeniem zaobserwowali rzadkie gatunki ptaków w każdym miejscu, zmniejszył się w ostatnich latach, ale wzrósł w weekendy. Stwierdziliśmy również, że odsetek kobiet w grupach obserwatorów wzrósł w ostatnich latach. Ponadto, „obserwatorki” ptaków częściej uczestniczyły w obserwacjach bardziej powszechnych rzadkości niż mężczyźni. Uzyskane przez nas wyniki wskazują, że na liczbę obserwatorów przyjeżdżających w miejsce wykrycia rzadkich gatunków ptaków mogą wpływać różne czynniki, w tym rzadkość gatunków, rok i odległość od miast. Dynamiczny wzrost udziału kobiet w obserwacjach ptaków w Polsce przypomina trendy odnotowane w innych krajach, a na zwiększone ich zaangażowanie w obserwacje częstszych rzadkości mogą potencjalnie wpływać odmienne motywacje. Read the free Plain Language Summary for this article on the Journal blog.

Birds sitting or feeding on live large African herbivorous mammals are a visible, yet quite neglected, type of commensalistic–mutualistic association. Here, we investigate general patterns in such relationships at large spatial and taxonomic scales. To obtain large-scale data, an extensive internet-based search for photos was carried out on Google Images. To characterize patterns of the structural organization of commensalistic–mutualistic associations between African birds and herbivorous mammals, we used a network analysis approach. We then employed phylogenetically-informed comparative analysis to explore whether features of bird visitation of mammals, i.e., their mean number, mass and species richness per mammal species, are shaped by a combination of host mammal (body mass and herd size) and environmental (habitat openness) characteristics. We found that the association web structure was only weakly nested for commensalistic as well as for mutualistic birds (oxpeckers Buphagus spp.) and African mammals. Moreover, except for oxpeckers, nestedness did not differ significantly from a null model indicating that birds do not prefer mammal species which are visited by a large number of bird species. In oxpeckers, however, a nested structure suggests a non-random assignment of birds to their mammal hosts. We also identified some new or rare associations between birds and mammals, but we failed to find several previously described associations. Furthermore, we found that mammal body mass positively influenced the number and mass of birds observed sitting on them in the full set of species (i.e., taking oxpeckers together with other bird species). We also found a positive correlation between mammal body mass and mass of non-oxpecker species as well as oxpeckers. Mammal herd size was associated with a higher mass of birds in the full set of species as well as in non-oxpecker species, and mammal species living in larger herds also attracted more bird species in the full set of species. Habitat openness influenced the mass of birds sitting on mammals as well as the number of species recorded sitting on mammals in the full set of species. In non-oxpecker species habitat openness was correlated with the bird number, mass and species richness. Our results provide evidence that patterns of bird–mammal associations can be linked to mammal and environmental characteristics and highlight the potential role of information technologies and new media in further studies of ecology and evolution. However, further study is needed to get a proper insight into the biological and methodological processes underlying the observed patterns.

Matching the timing of spring arrival to the breeding grounds with hosts and prey is crucial for migratory brood parasites such as cuckoos. Previous studies have focused mostly on phenological mismatch between a single cuckoo species and its hosts but information regarding climate-driven mismatch between multiple sympatric cuckoo species and their hosts and invertebrate prey is still lacking. Here, we analysed long-term data (1988–2023) on the first arrival date of two declining migratory cuckoo species and their 14 migratory host species breeding in sympatry and prey emergence date in Tatarstan (southeast Russia). We found that the common cuckoo ( Cuculus canorus ; wintering in Africa) generally arrived on breeding grounds earlier than the oriental cuckoo ( Cuculus optatus ; wintering in southeast Asia and Australia). Both cuckoos have advanced their arrival dates over 36 years but less than their hosts, potentially resulting in an increasing arrival mismatch between cuckoos and their hosts. Moreover, cuckoo arrival advanced less than the emergence date of their prey over time. These observations indicate that climate change may disrupt co-fluctuation in the phenology of important life stages between multiple sympatric brood parasites, their hosts and prey with potential cascading consequences for population dynamics of involved species.

A collection of exotic birds deposited in the Šariš Museum in Bardejov (SMB), Slovakia, has not been evaluated critically since their deposition. We assessed the accuracy of identification of 465 bird specimens deposited in SMB with native distributions outside of Slovakia. Specimens belonged to 322 species of 82 families and 26 orders. Of the specimen represented, 34 belonged to species considered as ‘near-threatened’ (7.3%), 16 as ‘vulnerable’ (3.4%) and one as ‘endangered’ (0.2%). The SMB collection holds 10 of 28 extant Cuban endemic species and another 11 species endemic to the Caribbean archipelago. Even among birds that are relatively easy to identify, many specimens were identified incorrectly or species identification was missing. Of 465 specimens evaluated, 95 (20.4%) were identified incorrectly or were missing species identification, and another 79 (17%) were identified correctly, but their names have changed over time due to taxonomic shift, thus they required correction.

The coronavirus disease 2019 (COVID-19) pandemic and respective shutdowns dramatically altered human activities, potentially changing human pressures on urban-dwelling animals. Here, we use such COVID-19-induced variation in human presence to evaluate, across multiple temporal scales, how urban birds from five countries changed their tolerance towards humans, measured as escape distance. We collected 6369 escape responses for 147 species and found that human numbers in parks at a given hour, day, week or year (before and during shutdowns) had a little effect on birds’ escape distances. All effects centered around zero, except for the actual human numbers during escape trial (hourly scale) that correlated negatively, albeit weakly, with escape distance. The results were similar across countries and most species. Our results highlight the resilience of birds to changes in human numbers on multiple temporal scales, the complexities of linking animal fear responses to human behavior, and the challenge of quantifying both simultaneously in situ. A study on urban birds' tolerance towards humans highlights their resilience to changes in human numbers, induced by COVID-19 shutdowns, across multiple temporal scales.

Bats (Chiroptera) and Common Swifts (Apus apus) are excellent fliers that use buildings as roosts and breeding sites in urban areas. Some predators have recently become adapted to hunting formerly unavailable prey. One such urban predator is the European Kestrel (Falco tinnunculus). We analyzed the diet and foraging behaviour of this species in Bardejov, North-Eastern Slovakia. In several observed breeding pairs, some bird began to hunt bats using novel foraging behaviour: sit-and-wait above ventilation channels of building facades where bats roosted, using ambush and perching tactics. Kestrel pairs that specialised in hunting bats also hunted Swifts. We did not find significant differences between Kestrel sexes in hunting bats and Swifts, but Kestrels preying on bats and Swifts had significantly higher breeding success than those that did not. Recently, Kestrels and their novel prey, bats and Swifts, have become endangered by rapidly-improved insulation of building facades in Central Europe. This intervention simultaneously destroys breeding and roosting places and potentially causes the collapse of urban populations of the European Kestrel.