first_page settings Order Article Reprints Open AccessArticle A Comparison of the Behaviour, Population Size and Sex Ratio of Mallards (Anas platyrhynchos) in Urban and Agricultural Areas of South-Eastern Poland by Hubert Jaworski 1 [ORCID] , Marian Flis 1 [ORCID] , Piotr Czyżowski 1 [ORCID] and Jacek Piórkowski 2,* [ORCID] 1 Department of Animal Ethology and Wildlife Management, Faculty of Animal Sciences and Bioeconomy, University of Life Sciences in Lublin, Akademicka 13, 20-950 Lublin, Poland 2 Department of Pathomorphology and Forensic Medicine, Faculty of Veterinary Medicine, University of Life Sciences in Lublin, 20-950 Lublin, Poland * Author to whom correspondence should be addressed. Diversity 2026, 18(5), 304; https://doi.org/10.3390/d18050304 Submission received: 14 April 2026 / Revised: 13 May 2026 / Accepted: 14 May 2026 / Published: 18 May 2026 (This article belongs to the Section Animal Diversity) Download keyboard_arrow_down Browse Figures Versions Notes Abstract This study presents the results of research into the behaviour of mallard (Anas platyrhynchos) populations during the winter months (January 2025 and 2026) in urban and non-urban areas across selected regions of south-eastern Poland. The research was conducted on selected stretches of the Bystrzyca and Czerniejówka rivers through direct observations of the birds and their flocks. Flight-distance measurements were obtained using a laser rangefinder. The results indicate a significantly higher bird density and the formation of larger flocks in urban environments. In agricultural areas, the sex ratio of mallards was more balanced. In urban areas, however, a skewed sex ratio in favour of males was observed. The analyses reveal significant differences in the degree of skittishness between urban and agricultural areas. Within the city, the population is characterised by a limited, even negligible, degree of skittishness, in contrast to agricultural areas. These results confirm previously published data regarding the marked decline in birds’ skittishness in urbanised areas. The data clearly indicate the progressive synurbanisation of this species.