Common Wood Pigeon (Columba palumbus): An Avian Bioindicator of Antimicrobial Resistance at the Human–Wildlife Interface

Antimicrobial resistance (AMR) is a silently escalating global crisis, presenting a specific challenge for the One Health approach. Landscapes can serve as reservoirs of AMR bacteria and genes, while synurban wildlife may act as vectors of bidirectional exchange. However, these species can also be utilised as sentinels of landscape AMR load. Herbivorous avian bioindicators, such as the Common Wood Pigeon (Columba palumbus), continuously sample the landscape during foraging and drinking, providing a homogenous spatial overview on the state of AMR. This study aimed to investigate the potential of this species for assessing the impact of landscape diversity on bacterial communities and their AMR patterns. Toward this objective, two spatial units of 4 km in diameter located at an upstream and a downstream section of a river, relative to a provincial town, were compared using 16 cloacal samples per site. Heterotrophic plate count techniques resulted in 60 isolates, of which 48 were identified, and 35 were tested for AMR using the VITEK 2 Compact system. The association between bacteriological findings and landscape diversity was analysed using Rényi diversity profiles. The Gram-positive/Gram-negative ratio was the only parameter that proved to be significantly different between the two study sites. The investigation detected six MDR isolates, with two methicillin-resistant phenotypes (Staphylococcus gallinarum, Mammaliicoccus lentus) and two carbapenem-resistant Pseudomonas fluorescens isolates. We established that the small sample size limits drawing definitive conclusions. However, exploring the link between landscape diversity and the cultivable faecal microbiota of herbivorous birds is a promising approach for more extensive research.