Habitat selection and response to playback in wintering Water Rails Rallus aquaticus. Issue 4 (2nd October 2019) - Polak, Marcin
ABSTRACT: Capsule: Wintering Water Rails Rallus aquaticus prefer small and narrow rivers, with large patches of wet emergent vegetation, and showed active response to playback, especially when they occurred in pairs. Aims: To investigate the habitat preferences and behaviour of Water Rails wintering in riverine ecosystems in eastern Poland. Methods: The study assessed factors driving the occurrence of Water Rails over two winter seasons. Standardized playback stimulation was used to increase bird detection and assess the behavioural response. The mixed model approach allowed the comparison of occupied sites and randomly selected control points, as well as allowing the identification of factors related to the birds' vocal response. Results: Water Rails occurred on 17–18% of sample points, of which one-third were occupied intensely throughout the whole winter from December to February. Individuals chose places characterised by narrower sections of the riverbed, with a larger cover of wet emergent vegetation. Birds responded to playback with varying levels of aggression; in 56% of cases, Water Rails approached the speaker and produced territorial calls. The level of territorial reaction was higher at sites occupied by two birds, in early winter periods and with higher average temperature. Conclusion: Natural riverine systems, with slow-flowing water and emergent wet vegetation, provide important habitats for Water Rails during the winter season; the species habitat requirements in winter were in general comparable to those of the nesting period. The strong vocal reaction shown, especially at sites occupied by two individuals, indicates the occurrence of strong territorial behaviour also outside the breeding season.