Alcedo atthis
Unmistakable bird in most situations. Azure blue above, and orangy brown below. Very short tail, and large head with long and heavy bill. Often overlooked despite it's bright colours, due to small size and obscuring habitat. Often one only catches a glimpse of the light blue back, when it flies away close to the water surface in a whirring, darting motion.
Most heard is the thin and penetrating contact call: A short "tzee", or disyllabic "tzee-tzu", with a ringing metallic quality. In excitement it is often alternated with ringing trills "tzeerrrrrrrrrr".
Wikipedia: map (se also Xeno-canto below)
Birdlife ecology
