Deep Blue Sea (1999)

Revealing mistake: When the shark first attacks and bites off Jim's arm, you can briefly see his real arm under his shirt as he's screaming in pain. (00:34:10)

Russell Franklin: Just what the hell did you do to those sharks?
Dr. Susan McCallister: Their brains weren't large enough to harvest sufficient amounts of the protein complex. So we violated the Harvard Compact. Jim and I used gene therapies to increase their brain mass, a larger brain means more protein. As a side effect the sharks got smarter.
Janice Higgins: You stupid bitch!

Trivia: All three sharks are killed in almost the same way the first three sharks is killed in the 'Jaws' movies. Blown up with gas, electrocuted and the last one is blown up.

Question: How did they do the scene when one of the sharks ate the bird? I know they used animatronic sharks for any interaction with the people, so did they use the same method for the bird? It was "inside" the shark after all.