We were in Tulcea on the edge of the Danube Delta on our floating hotel in early June. Both male and female House Sparrows were flying out from the boats skimming and hovering low over the water, to catch the recently emerged giant Tisza Mayflies (Palingenia longicauda), which are the biggest mayfly in Europe. They then flew back to the boats, stripped the wings and legs and carried off the huge yellow and black sacks of protein. The boat decks were strewn with inert wings. Fascinating behaviour.