Nest tree selection in a crowded introduced population of Monk Parakeet (Myiopsitta monachus) in Rome (central Italy): evidence for selectivity

Unique among parrots, Monk Parakeets nest socially (many nests in one nest structure) and with a gregarious spatial pattern (many nest structures in a single breeding area). In this work, we studied nest site selection, tree size (diameter and height), and nest opening orientation in an introduced population of Monk Parakeets occurring with a high nest density in an urban park of Rome (central Italy). Of the 73 nest structures we examined, 72% were built on Cedrus libani showing a significant preference for this tree species when compared to tree species availability. Monk Parakeets nested on taller trees and on trees with a significantly larger diameter at breast height. Nest structures had one to four nest openings, which appeared to be randomly orientated. Monk Parakeets build nests relatively close to other social nests (at a distance of about 3 m on average); this behaviour maybe representing a group defence against predators.