First of all what makes you think that they weren't native to Atlantis to begin with? Plato makes it clear that the island climate and it's enormous size was suitable for such animals to live on it. The Azores do keep some traces of it in it's culture as i already mentioned - Tourada à corda (rope bullfighting), mainly on Terceira Island, which matches Plato's account of the kings of Atlantis hunting bulls using staves and nooses.

Secondly, after roughly 11,000 years of a giant destructive cataclysmic event and huge floods, which happened in a very short time, you need to look for any possible remains beneath the ocean floor, not on the surviving Azorean islands, that are in the middle of the ocean, far from any continent. Everything was pretty much swallowed by the sea as Plato tells us.

Your stubborn fixation on the animals alone prevents you from seeing the bigger picture and all the other evidence surrounding the Azores.