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

The nest sites and habitat features of the area around nests in a population of Jackdaws breeding in the centre of Rome, Italy, were studied. Occupied nests (n = 41) had a predominantly south-easterly exposure and were located on average 20 ± 8 m above the ground. The availability of suitable nest holes positively influenced the size of breeding colonies. The preference for SE-facing holes could be affected by winter winds, which blow from the NW. To describe the habitat conditions in 20 Jackdaw nesting areas in Rome, in comparison 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 the total area of occupied plots and random plots, respectively. Ruderal areas covered 5% of the total area in occupied plots and 0.4% in random ones, wooded areas correspondingly 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 the interspersion of ruderal areas, gardens, and built-up districts that provide suitable nest sites. Effective protection measures in urban areas should concentrate on the conservation both of suitable cavities in old buildings and of relict patches of ruderal and open habitats bordering city centres.