Now that Trouble is back, the limiting factor on bear and elephant acquisition is just the availability of those of the Animorphs who experience nonzero parental supervision. There is a coincidence of Renée being out well past zoo closing time and Robin's mother being occupied the day after Trouble's return.

Everybody morphs pigeons and they fly to the zoo. The three of them that are going to get bears head for the bear enclosure, and Trouble, of course, is the bait.