Successful Colonization of a Novel Urban Environment is Associated with an Urban Behavioural Syndrome in a Reed‐Nesting Waterbird

Urbanization is currently considered one of the most rapid types of global environmental change. More and more wildlife species are subject to increasing anthropogenic disturbance, but only some of them adapt to become successful urban exploiters. Although a number of fixed life history characteristics may enhance population persistence in an urbanized landscape, behavioural traits are thought to be critical for colonization of a novel urban environment. Within the class of birds, behavioural responses to urban environment have been assessed mostly for passerine species. Here, I examined behavioural alterations in a recently founded urban population of a reed‐nesting rallid species, the Eurasian coot Fulica atra. I found that urban coots adapted to nest in anthropogenically transformed littoral zones with scarce or no emergent vegetation, which precluded efficient nest concealment. Despite this, urban individuals spent, on average, less time incubating due to more frequent bouts off the nest than suburban conspecifics. This pattern was likely possible due to the relaxation of predation pressure in the colonized urban environment. Urban birds were also more aggressive, approached a human intruder at the nest more closely and were more likely to actively defend their nests. Finally, they had a reduced level of physiological stress (as measured with heterophil/lymphocyte ratio) when compared with suburban individuals. In conclusion, the behaviour of coots from the recently founded urban population was consistent with behavioural syndromes found in typical urban exploiters. The results support the central role of behavioural adaptation in successful colonization of novel environments by wildlife.