Finally, after many times passing by the walkthrough raptor aviary looking at every corner for this species, I saw it at closing time (18:00) engulfing dead chicks :) :)
Checked the top of all the two or three wooden houses (as a Spanish I also don't knew a better name) specifically for this species in 2-3 visits along the day, and I was desperated because the eagle was no show. Also checked every branch and place where the eagle could be. So finally I was very happy when I saw it in the soil, just at the closing time, as said in the description