Rashi points out that because the dogs did not bark when the Jews left Egypt, they were rewarded with the basar neveilah.
Since they were uniquely rewarded, this implies that all the other animals did speak at yetzias mirzrayim.
The majority of the livestock were killed in the plagues. The tzefardea all died. The locusts were swept away. And for the most part the wild animals fled after the plague of Arov. There were very few animals left to make noise at that time.
It would appear that only smaller wild animals with a propensity to hang around human habitations for food and shelter would have remained after the plagues, such as racoons and squirrels, but those didn't exist in Egypt. The most notable of this group of animals is the shu'al.
So my question is this:
What did the Fox say?