Nest site and breeding habitat characteristics in urban jackdaws Corvus monedula in Rome (Italy)

Salvati, Luca

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Tytuł: Nest site and breeding habitat characteristics in urban jackdaws Corvus monedula in Rome (Italy)

Abstrakt:

Nest sites and habitat features of the area around nests in a population of Jackdaws breeding in the centre of Rome, Italy was studied. Occupied nests (n = 41) had a predominant south-east exposition and were placed on average 20 ą 8 m above the ground. The availability of suitable holes positively influenced the size of breeding colonies. The preference of SE exposure of nest holes could be affected by the winter wind which blows from NW directions. To describe habitat conditions at 20 nesting areas of the Jackdaws in Rome, in comparision with 14 randomly selected sites from the same area 25 variables in plots within a 28.8 ha area were measured. Built-up districts covered on average 77% and 78% of total surface in occupied plots and in random plots, respectively. Ruderal areas covered 5% of total area in occupied plots and 0.4% in random ones, wooded areas - 20% and 12%. Stepwise discriminant function analysis carried out on habitat variables in nesting areas and random plots provided a model based on the proportion of ruderal areas and gardens that correctly classified 90% of cases. Jackdaws are associated with habitats characterised by interspersion of ruderal areas, gardens, and built-up districts that provide suitable nest sites. Effective protection measures in urban areas should concentrate on conservation of both suitable cavities in old buildings and relict patches of ruderal and open habitats bordering city centres.