I think JA uses the Royal Menagerie to illustrate how John's words to Elinor and Marianne in chapter 33 ring hollow. He tells them that he hasn't had a moment to spare for them:

"I wished very much to call upon you yesterday," said he, "but it was impossible, for we were obliged to take Harry to see the wild beasts at Exeter Exchange: and we spent the rest of the day with Mrs. Ferrars. Harry was vastly pleased. This morning I had fully intended to call on you, if I could possibly find a spare half-hour, but one has always so much to do on first coming to town."