Monk Parakeet Colony — Barcelona

The parks and gardens of Barcelona host the largest monk parakeet population in Europe — an estimated 10,000 birds descended from escaped cage birds that have established a self-sustaining feral population since the 1970s, building enormous communal stick nests on the city's palm trees, lamp posts, and ornamental structures in one of Europe's most unusual and visually arresting urban wildlife spectacles. The monk parakeet's communal nests — some exceeding a metre in diameter and housing twenty pairs simultaneously — create extraordinary architectural structures in the crowns of the Citadel Park's trees and the Barceloneta waterfront palms, and the constant chattering, squabbling, and acrobatic flight of the bright green birds provides a tropical-atmosphere wildlife encounter in the heart of a major European city. The Parc de la Ciutadella and the cemetery of Poblenou host the densest colonies, and early morning walks through these sites produce encounters of considerable charm with dozens of parakeets in full nesting activity at eye level from the park paths. The parakeets' adaptability to the Mediterranean urban environment has created a genuinely novel urban ecosystem unplanned by any conservation body, and the birds' interaction with native species — competing for nest holes with hoopoes and rollers — is an ongoing ecological experiment visible to any Barcelona visitor. The colonies are most active and visible from February through July during the breeding season.