Great White Pelican is registered for the Romanian Danube Delta around Mahmudia and its lakes and channels. That delta itinerary is separate from cruises between Passau, Vienna, Bratislava and Budapest. BirdLife identifies a very wide-ranging species, but a global range map does not locate a viewing flock. Source: https://datazone.birdlife.org/species/factsheet/great-white-pelican-pelecanus-onocrotalus

Danube
Romania: Danube Delta around Mahmudia and delta lakes/channels; separate lower-Danube/delta itinerary, NOT Passau–Vienna–Bratislava–Budapest. Viewing guidance: Spring–autumn; open delta lakes, local boat excursion. Checklist establishes occurrence, not guaranteed daily sightings.

Black Kite
Black Stork