Abstract
Knowing the ecological requirements of bird species is essential for their successful conservation. We studied the niche characteristics of birds in managed small-sized green spaces in the urban core areas of southern (Kavala, Greece) and northern Europe (Rovaniemi, Finland), during the breeding season, based on a set of 16 environmental variables and using Outlying Mean Index, a multivariate ordination technique. Overall, 26 bird species in Kavala and 15 in Rovaniemi were recorded in more than 5% of the green spaces and were used in detailed analyses. In both areas, bird species occupied different niches of varying marginality and breadth, indicating varying responses to urban environmental conditions. Birds showed high specialization in niche position, with 12 species in Kavala (46.2%) and six species in Rovaniemi (40.0%) having marginal niches. Niche breadth was narrower in Rovaniemi than in Kavala. Species in both communities were more strongly associated either with large green spaces located further away from the city center and having a high vegetation cover (urban adapters; e.g., Common Chaffinch (Fringilla coelebs), European Greenfinch (Chloris chloris), Eurasian Blue Tit (Cyanistes caeruleus)) or with green spaces located closer to the city center and having high gray area cover and anthropogenic disturbance level (urban exploiters; e.g., Western Jackdaw (Corvus monedula), House Sparrow (Passer domesticus), Eurasian Magpie (Pica pica)). The eleven species that were common to both study areas similarly used the environmental variables and had similar niches, indicating that birds respond similarly to urbanization irrespective of latitude. Sixteen species in Kavala and eleven species in Rovaniemi were identified as conservation priority species, based on their niche specialization level and conservation status. The management actions proposed for the conservation of priority species will also benefit other species with similar ecological requirements and ultimately help maintain diverse bird communities in small-sized green spaces in urban core areas.
Highlights
Hutchinson’s [1] concept of the realized niche refers to the range of environmental conditions in which a species can survive, grow, reproduce and maintain a viable population, even in the presence of competitors and predators
Species can be assigned along a narrow-broad niche continuum, from specialists that use a narrow range of environmental conditions to generalists that use a broad range of environmental conditions
The average marginality of all species, the criterion optimized by OMI analysis, was significantly different from the mean habitat condition (p < 0.001)
Summary
Hutchinson’s [1] concept of the realized niche refers to the range of environmental conditions in which a species can survive, grow, reproduce and maintain a viable population, even in the presence of competitors and predators. Defined the ecological niche as an n-dimensional hypervolume (with ‘n’ being the number of environmental conditions examined) that determines species distribution. Birds are important components of urban landscapes, promoting ecosystem health [3]. They are good indicators of the diversity of other animal groups and of habitat. Sustainability 2021, 13, 6327 condition [4,5] because they are conspicuous, easy to quantify and quickly respond to habitat changes caused by urbanization [6,7]. The importance of urban green spaces has greatly increased during the COVID-19 pandemic
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