Final answer:
The passage does not provide information about Jonas riding an animal in Chapter 16; it appears to be from a different story about a character named Sylvia.
Step-by-step explanation:
The animal that Jonas gets to ride in Chapter 16 is not mentioned in the passage provided. The passage instead seems to be related to a story about a character named Sylvia and her encounter with a heron. Therefore, it is not possible to answer the question with certainty based on the information given.
This answer would require a reference to Chapter 16 of 'The Giver' by Lois Lowry, which is not included in the provided text. The passage speaks more about a secret Sylvia discovers and her challenging journey down from a tree.