Aviary Door
For an aviary entrance, build a 3⁄4-sized door. The birds are more likely to fly up and past you when entering a flight than they are to try to fly down. For additional security, hang lengths of plastic chain from the top edge of the door frame to about 1 inch from the bottom. The motion of the chain frightens the finches, so they are unlikely to attempt flying toward it. A piece of shade cloth can be used the same way.
Keep a sharp eye on the birds as you enter and exit, and try to exit the aviary in a backward direction. Install a “hook-and-eye” fastener to keep the door closed.
Flooring
Unlike soil, sand flooring does not provide a medium for bacterial growth. Before adding sand, use wire to create the bottom of the flight (the same wire as the rest of the flight) in order to prevent predatory animals from digging under. Fill it with “play sand,” which is sterilized and intended for use in children’s sandboxes.
To create a sand-bottom aviary, sprinkle an entire can of Sevin Dust over the floor. Sevin Dust in an insecticide that is safe to use around birds and is available at most garden supply stores. Lay a double layer of canvas sail-cloth (also available at home improvement stores), then add sand to a depth of about 4 inches all over the floor. You can mix in a few cups of garden lime with a hand trowel to further reduce bacterial growth and neutralize odors. Sand-bottom aviaries can be sifted for cleaning as needed, and disinfect every few months by pouring a diluted bleach and water solution of 1 teaspoon of bleach per 1 gallon of water over the sand. Replace the sand completely at least every other year.
Watering and Perching
Use saucers on tall iron plant tripods for water watering stations, and place it directly beneath the seed tripod. This helps keep seed hulls and droppings out of the water, while allowing for both bathing and drinking. Place the highest perches near the roof to encourage the birds to roost in a more protected area.
Décor Chore
There are many bird-safe plants that are bird safe to decorate the interior of your outdoor aviary. Eye-catching, bird-safe plants include ferns, palms, evergreen, ficus and bamboo. Check out BirdChannel.com's list of nontoxic and toxic plants.
Feel free to mix in non-fraying artificial plants for a lush look with less maintenance. You can keep artificial plants out of reach of your birds, so they can enjoy but not be tempted to eat. Wash artificial plants with hot, soapy water and rinse carefully before use.
I offer untreated grapevine wreaths for perching. Hang a few vines straight down from the roof for a nice visual effect. Finches enjoy landing on them to swing back and forth.
A string of outdoor-safe lights set on a timer provides some light during the night in case a cat (or other animal) startles the birds. This is especially important for birds kept outside year-round because the short days of winter don’t allow as many hours for feeding. Birds expend a lot of energy keeping their body temperature up in cold weather and being able to see and feed is important.