1. Animals cannot talk in the usual sense, as their vocal chords are different then ours.
2. Some exceptions - like parrots - exist. They mimic talk, as opposed to really talking.
3. But no matter, there are no animals who have the ability to intelligently communicate (talk) as we define it.
The above are facts.
Some animals may be able to communicate in ways we don't know about, or can't understand. This has been hypothesized, but not proven.
Because they just cant :)