There is an Ibis on the rock behind the two penguins with their backs to the camera - it was partly why I took the photo. It is a heron on the left. Herons are everywhere in the zoo, which has the largest urban heronry in Europe.
the ibis is a Sacred Ibis. There used to be a small wild population in Barcelona - from the early 1970s through to the start of the 2000s - which was initially derived from birds escaping from the zoo.