Farah Abou Zeid

Urban areas are known to have high levels of noise pollution, which can impact an animal’s antipredator behavior. Noise can either distract the animal or mask the sounds of a predator, increasing the animal’s vulnerability to predation. However, the prey may increase vigilance in noisier environments, thus reducing energy and time spent on other activities. Alert Distance (AD) refers to the distance at which an animal becomes alert to a potential predator approaching. Flight Initiation Distance (FID) is the distance from the potential predator at which the animal flees. We studied the impact of ambient noise pollution on the AD and a corrected FID (FID/AD) of Eurasian Magpies (Pica pica) using a field investigator as a potential predator walking towards birds at a constant speed. We found that the noise level did not affect the AD. Still, noise had a negative effect on the Eurasian Magpies’ FID/ADs, suggesting that noise may slow their reaction to a potential threat but not their ability to detect it. Thus, our research highlights that urban noise pollution can increase an individual's vulnerability to predation, even when predators are still detectable. Ambient noise may distract the bird by diverting some of its limited attention and causing a delayed response to the predators. Alternatively, noise could be masking auditory cues that would have otherwise been added together with visual cues to cause an enhanced response. More research is necessary to understand the effects of noise pollution on the antipredator behavior of birds in urban areas, taking into account the specific strategies and adaptations of each species.

Understanding habitat and spatial overlap in sympatric species of urban areas would aid in predicting species and community modifications in response to global change. Habitat overlap has been widely investigated for specialist species but neglected for generalists living in urban settings. Many corvid species are generalists and are adapted to urban areas. This work aimed to determine the urban habitat requirements and spatial overlap of five corvid species in sixteen European cities during the breeding season. All five studied corvid species had high overlap in their habitat selection while still having particular tendencies. We found three species, the Carrion/Hooded Crow, Rook, and Eurasian Magpie, selected open habitats. The Western Jackdaw avoided areas with bare soil cover, and the Eurasian Jay chose more forested areas. The species with similar habitat selection also had congruent spatial distributions. Our results indicate that although the corvids had some tendencies regarding habitat selection, as generalists, they still tolerated a wide range of urban habitats, which resulted in high overlap in their habitat niches and spatial distributions.

Most ecological studies use remote sensing to analyze broad‐scale biodiversity patterns, focusing mainly on taxonomic diversity in natural landscapes. One of the most important effects of high levels of urbanization is species loss (i.e., biotic homogenization). Therefore, cost‐effective and more efficient methods to monitor biological communities' distribution are essential. This study explores whether the Enhanced Vegetation Index (EVI) and the Normalized Difference Vegetation Index (NDVI) can predict multifaceted avian diversity, urban tolerance, and specialization in urban landscapes. We sampled bird communities among 15 European cities and extracted Landsat 30‐meter resolution EVI and NDVI values of the pixels within a 50‐m buffer of bird sample points using Google Earth Engine (32‐day Landsat 8 Collection Tier 1). Mixed models were used to find the best associations of EVI and NDVI, predicting multiple avian diversity facets: Taxonomic diversity, functional diversity, phylogenetic diversity, specialization levels, and urban tolerance. A total of 113 bird species across 15 cities from 10 different European countries were detected. EVI mean was the best predictor for foraging substrate specialization. NDVI mean was the best predictor for most avian diversity facets: taxonomic diversity, functional richness and evenness, phylogenetic diversity, phylogenetic species variability, community evolutionary distinctiveness, urban tolerance, diet foraging behavior, and habitat richness specialists. Finally, EVI and NDVI standard deviation were not the best predictors for any avian diversity facets studied. Our findings expand previous knowledge about EVI and NDVI as surrogates of avian diversity at a continental scale. Considering the European Commission's proposal for a Nature Restoration Law calling for expanding green urban space areas by 2050, we propose NDVI as a proxy of multiple facets of avian diversity to efficiently monitor bird community responses to land use changes in the cities.

The coronavirus disease 2019 (COVID-19) pandemic dramatically altered human activities, and, during shutdowns. Here, we evaluated whether urban birds from five countries changed their tolerance towards humans during the COVID-19 shutdowns. We collected 6369 flight initiation distance estimates for 147 bird species and found that human numbers in parks (at a given hour, day, week or year - before and during the COVID-19 shutdowns) had a little effect on birds’ tolerance of approaching humans. Apart from the actual human numbers in the area (hourly scale), the effect of human activity at other temporal scales centered around zero. The results were similar across countries, for most species or when we restricted our analyses only to species sampled both before and during the COVID-19 shutdowns. As expected, the level of daily human presence in parks (measured by Google Mobility Reports) correlated negatively with the stringency of governmental restrictions (a weekly proxy for human presence) and was overall lower during COVID-19 shutdowns than during the post-shutdown year (2022). 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 .