All our outdoor facilities are tied into each other, but are not accessible except by outer doors. Where appropriate, special screens keep animals from seeing who’s in the next facility (for example, the small mammals don’t need to see the birds of prey!). The outdoor facilities are away from the house to keep them as secluded from human noises as possible, but the perimeters are visible from the house so we can see if there is a problem (stray cat, snake, etc.) that needs our interference.
An aviary sits directly outside one of the pens. One pen holds various small mammals. We have two bear pens and are working on a third.
In the bear pens, a double entry system was installed so the caretaker could enter and close the outer door before ever opening the door to the pen. Tucked in one corner or each pen is a "cave" for them to sleep in or hide inside if they hear a strange noise. Because bears like to sleep in den-like areas in the wild, this gives them that same sense of security.
Also inside each bear pen is a large trough, used as much for playing as drinking. Most cubs adore water and will play in the tub the same way small children play in a pool. They take their paws and splash each other, slide on their bellies (the tub is on a small incline) and spray water out their lips. The bear pens have plenty of things for the cubs to climb on to prepare them for climbing high up in trees in the future.
There are other pens we'd love to have, but those will, of course, take funds.