Use of tools. Learning through imitation. Representing abstract concepts. Basic design of the task with the pigeons pecking at pictures for food. Understanding arithmetical concepts.
Chickens make different sound to convey warning about a ground predator vs. an aerial predator.
This is very impressive. BUT, humans can invent and use NEW words. The dog walked to the girl. That is, could the dolphins understand that the exact same words, arranged in two different orders meant two different things. The answer was yes.