Enclosure Placement Rule Variant: Enclosures can only be placed where they will connect to an existing Bear House of the same type. Or another Enclosure of the same type.
Thematically, Bears aren’t moved from their houses to another area of the park to be put on display, they are always connected to their House.
(When playing my first game (2 players), we had assumed this was already the placement rule – and were surprised that it wasn’t.)