It depends on what type/size your birdhouse is if it would be suitable for other birds. Some of the wren houses are awfully small for a Tree Swallow or Bluebird to nest in. Bluebirds need a 1.5 inch hole, swallows prefer that too but can get in a smaller hole. Chickadees also prefer the 1.5 inch hole but can get in a 1 1/8 inch hole. A housewren will enter any size hole, not much deters them except keeping the nestboxes far away from brush and trees. House Sparrows can enter a 1 1/4 or larger hole, you would want to keep them from nesting in your birdhouse. A properly mounted nestbox is mounted on a slick metal pole with a predator baffle and at least 15-30 feet away from trees/fences/brush with no branches hanging over the box. Squirrels and or raccoons can and will get into nestboxes placed in/on trees or mounted on wooden posts. A metal plate on the front is to prevent woodpeckers from enlarging the hole. If the nestbox is mounted properly squirrels shouldn't be able to get to it to chew the opening. Here is a link to "lots" of info about cavity nesting birds..it is a bluebird site but has load of info about all cavity nesting birds and how to attract them and properly put up nestboxes for them.... Donna Here is a link that might be useful: Cavity nesting bird info.....sialis...

Well Rachel, here I am, back a little wiser and a little chagrined. I walked to my window today only to see four sparrows crowded in my chickenwire-wrapped feeder! You are right, they ARE smart. So... I went out and made all of the larger holes smaller (pinched and wired them, very carefully). Back in the house I go and watch, and the house sparrows flap around and hang from the outside, confounded. A chickadee flies in, gets some seed, flies out, with the sparrows watching. Then one of the sparrows goes around the feeder and zips inside the cage. Then I am the one who is confounded! And to add insult to injury, a sparrow was eating nyjer seed out of the finch feeder! Of course I am a bit discouraged by this, (the cloud of sparrows flying out of my tree made me think of Albert Hitchcock's THE BIRDS), but I think what I'll do is take the feeders down and start over, being very stingy and careful with the seed (and only safflower). I will figure this out and I will check back here at the forum for advice. Thanks for reading my (not uncommon I guess) tale of woe. I might be down but I'm not out!

Well Charlie, you first have to consider which bird species might actually use a box in that location. I am thinking Chickadees or Wrens are most likely. So, a nice sturdy box that is intended for Wrens would be good. The entrance hole on Wren boxes would work for Chickadees or Wrens. You don't need perches on the box. Most species of cavity nesting birds will not nest too close to more of the same species. So, I would start with one or two Wren boxes. I would watch them closely and make sure that the House Sparrows don't take them. Some here would tell you not to mount any birdhouse on a trellis for fear of easy access by snakes. My feeling is that cavity nesting birds were successfully using tree cavities well before man began to offer custom built housing for them. So, I would say go for it. Just don't let the House Sparrows have the boxes. Angie

there are two different types of birdhouses. Nesting boxes are for a pair who are sitting on eggs and can hold four or five babys and the parents and the hole should be small enough so larger birds can't enter and no perch near hole where bigger birds can perch and reach into the box. The other type are roosting boxes for winter time or cold climates where the birds can stay at night or during bad weather. they are usually larger and often with two or more openings and holes sizes according to which birds are wanting to roost. often birds such as chiskadees and nuthatches and tits ect will share a roost box. if you get lots of birds in one box inside perches work and the younger birds are usually close to full size by the winter months.