Brahminy Kite
Brahminy Kite and a common (Singapore) crow - First time I've seen these species together, a few Kites and crows flew together for maybe 15 minutes, then separated. The Kite is a raptor with a wide range of prey, including other birds.
White-bellied Sea Eagle
Whimbrels + Estuarine Crocodile - not a great shot, but interesting in that these crocs will eat virtually anything, and the birds were content staying close.