Reproduction and survival in the city: which fitness components drive urban colonization in a reed-nesting waterbird?

Włodarczyk

Journal of Avian Biology

et al. 2017

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Much effort has been devoted to identify ecological and life‐history traits which facilitate urban colonization by wild avian species, but surprisingly little is known about the population‐level mechanisms of urbanization processes. In general, two different patterns of urban colonization have been proposed: 1) the model of independent colonization predicts that birds colonize cities independently in different geographical regions; 2) the model of leapfrog colonization assumes a single colonization event, while additional urban populations are established from the initial urban populations. The aim of this paper was to determine the pattern of urban colonization in a common waterbird, the Eurasian coot Fulica atra. For this purpose, we analysed microsatellite variation in three pairs of urban and rural coot populations from central Poland. We found that a newly‐established urban population was genetically more similar to neighbouring rural populations than to long‐established urban populations, as indicated by the analysis of fixation index, genetic distance and Bayesian assignment of individuals to genetic clusters. These results are consistent with the model of independent colonization, where neighbouring rural populations are a source of individuals that colonize new urban areas. However, our analysis also showed significant differentiation between long‐established urban populations and adjacent rural populations, suggesting that genetic connectivity between two types of habitat decreases with increasing time since urbanization. Our study shows high complexity of urbanization processes in wild animal populations, as well as it underpins utility of molecular tools in studying population‐level mechanisms of urbanization.

Section: Methodsmentioning

confidence: 99%

How birds colonize cities: genetic evidence from a common waterbird, the Eurasian coot

Włodarczyk

Journal of Avian Biology

et al. 2017

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“…Eurasian coots nest in emergent shore vegetation on a wide range of still or slow‐flowing waters (Snow & Perrins ), but are usually secretive and highly timid towards humans while nesting in natural habitats. Although the recent urban colonization in central Poland yielded large reproductive benefits for this species (Minias ), it may be expected that those fitness advantages could have been only attained via a number of behavioural adaptations. To test this hypothesis, changes in three components of coot behaviour, that is nest‐site selection, nest attendance patterns and nest defence behaviour, were evaluated along the urbanization gradient of Łódź, a large city in central Poland.…”

Section: Introductionmentioning

confidence: 99%

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

2015

Ethology

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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.

“…Taking these results into account, it seems that food availability may not be an important component of territory selection by coots nesting in an urban landscape, or at least it may be of second importance when compared to brood safety that is provided by emergent vegetation. Previous comparisons of urban and suburban coot populations revealed that urban‐dwelling individuals were in much better nutritional condition than suburban conspecifics, which was mainly attributed to the availability of anthropogenic food (Minias, ). However, it is possible that an access to natural food resources (submerged macrophytes and aquatic invertebrates; Brinkhof, ) combined with food provided deliberately by humans makes urban coots virtually unlimited in terms of food availability.…”

Section: Discussionmentioning

confidence: 99%

Territory selection in the city: can birds reliably judge territory quality in a novel urban environment?

Janiszewski

2016

Journal of Zoology

Although territory selection is likely to be under strong natural selection, in many cases it might be impossible for individuals to judge territory quality directly in terms of fitness return. Thus, animals often rely on some indirect environmental cues in territory assessment and they may not be able to make optimal settlement decisions when subjected to a novel environment. The aim of this study was to investigate adaptiveness of territory selection in a newly established urban population (Ł od z, central Poland) of a waterbird, the Eurasian coot Fulica atra. For this purpose, we correlated occupancy rate of urban breeding territories over a 7-year period with basic fitness-related traits of coots. We found that the average number of fledglings raised by Eurasian coots increased with territory occupancy, indicating that birds were able to reliably judge territory quality and to choose nest sites which maximized their reproductive success. This conclusion was supported by the fact that in the process of territory selection coots used a set of habitat cues important for successful nest concealment and brood safety. In contrast, we found that coots showed no preferences for territories which provided easy access to anthropogenic food resources (via public feeding of waterbirds) and there was no relationship between condition of adult birds and territory occupancy, suggesting that either: (1) brood safety was a more important component in territory assessment than food availability, or (2) birds were unable to reliably judge food resources in a novel urban landscape.