Last saturday I went to Gunung Gede Pangrango National Park with my birding companion, Tri Susanti.
After a hiking of 3 hours (to many birds to discover!) we reached the Swamp (a forest clearing with head-high grass and a well known place in here).
Soon as we arrived we detect an adult Crested Serpent-eagle Spilornis cheela soaring.
Then displayed in flight (diving followed by an ascent flight with raised wings, beating them for a few seconds in that position, performed a few times).
We were still talking about this behaviour when a male Javan Hawk-eagle Nisaetus bartelsi (we weren’t able to tell the age of this bird), also started to display above (diving followed by an ascent flight and then gliding, also a few times).
After that a juvenile male Javan Hawk-eagle was seen interacting with an adult female, disappearing behind the canopy.
(E-bird list here)