Remiz pendulinus
Boicușul is the famous "architect" of the Delta. Although small and unobtrusive, it is famous for its extraordinary nest, suspended above the water. It is a bird that lives almost exclusively in areas where weeping willows touch their branches to the surface of water or reeds.
A small, elegant bird recognised by the broad black mask across the eyes, contrasting with the grey-white head and nape. The back is warm chestnut-brown. The bill is fine and sharply pointed — perfectly adapted for gleaning small insects and seeds from catkins and reed inflorescences.
Present on almost every willow-lined canal in the Danube Delta. Prefers areas with dense riparian vegetation and direct access to plant down (from willows or bulrushes) needed as nest-building material. Partly migratory, with some individuals remaining in the Delta year-round.
Feeds by carefully exploring reed and willow inflorescences, clinging acrobatically to thin branches and seed heads. The most spectacular behaviour is nest construction: the male weaves plant fibres and down into a complex, soft yet resilient pouch with a tubular side entrance — a masterpiece of animal engineering built with no tools but the bill, taking several weeks to complete.
A polygamous species: the male may begin several nests simultaneously to attract multiple females. The female incubates 5–8 eggs alone for approximately 13–14 days. The nest is so robustly constructed and securely anchored that it may hang on the branch for several years after being abandoned.
Least Concern (LC) globally. The Danube Delta is one of the most important European habitats for this species, thanks to its vast network of willow-lined canals — a riparian ecosystem rare in modern Europe. Maintaining willow gallery forest along the canals is essential for the species' conservation in the Delta.