Latest papers
Chatelain, M., Rubbmark, O., Rüdisser J., & Traugott. 2025. Urbanisation and Habitat Shape Resource-Driven Dietary Shifts in Wild Birds. BioRxiv. https://www.biorxiv.org/content/10.1101/2025.01.17.633593v1
Abstract
Urbanisation affects bird ecology and evolution, with changes in nutritional intake considered a key driver. However, most studies provide only snapshots of urban bird feeding ecology due to methodological limitations in analysing diets across space and time. Here, we address this gap by examining the diets of two common species with differing feeding ecologies: the great tit (Parus major) and blue tit (Cyanistes caeruleus). Diet samples from 370 birds, captured over a year at 147 locations across an urbanised landscape in Innsbruck, Austria, were molecularly analysed. Results revealed species-and season-specific diet patterns influenced by urbanisation: urban great tits exhibited higher diet diversity but reduced arthropod consumption during the breeding season, while urban blue tits compensated for lower moth intake by increasing their consumption of crab spiders and aphids. Prey consumption mirrored prey availability, highlighting resource-driven dietary shifts. Habitat type also played a significant role, with urban green spaces enhancing plant-based food diversity and residential areas increasing anthropogenic food consumption. These findings support the hypothesis that diet drives fitness and phenotypic differences between urban and rural bird populations. They highlight the need to consider both urbanisation levels and habitat characteristics to fully understand its ecological and evolutionary impacts.
Janas, K., Chatelain, M., Corsini, M., Da Silva, M., Wardecki, Ł., Szulc, J. & Szulkin, M. 2025. Bird colours in urban mosaics: A study of two passerines. BioRxiv. https://www.biorxiv.org/content/10.1101/2025.07.15.664885v1
Abstract
Urban environments are characterized by markedly altered conditions, which can exert a negative impact on the organisms that inhabit them. Among phenotypic traits most sensitive to urbanization is the colourful plumage of birds. One of the best studied examples might be the urban dullness phenomenon, described for carotenoid-based traits, referring to colours being subdued in urban areas. In contrast, melanin-based and structural colouration are still understudied in the context of urbanization. Moreover, much research focused on changes in mean trait expression, while the effect on phenotypic variation, vital from an eco-evolutionary perspective, was rarely studied in this context. Here, we examined urbanization-driven differences in expression and phenotypic variation of carotenoid-based, melanin-based and structural colours of two urban adapters, the great tit (Parus major) and the blue tit (Cyanistes caeruleus). Importantly, birds were sampled across multiple urban and suburban habitats, and replicated in eight Polish cities, located in the under-studied Central and Eastern European region. We found a consistent decrease in mean carotenoid chroma of great tit breast plumage in more heavily urbanized habitats. This trait was also characterized by higher urban phenotypic variation, which could stem from greater environmental heterogeneity in cities. In blue tits, we observed reduced brightness of breast feathers in urban city centres, and an increased brightness of blue tail feathers in more urbanized habitats. Our study sheds light on the complex pattern of colour trait sensitivity to urbanization and emphasizes the need for examining a wider range of species to gain greater insight into the eco-evolutionary processes acting in urban ecosystems.
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