Cover for birds
Birds need cover from predators and from severe weather. They also need places to perch and just to be.
Here's a "bird's eye" view of cover. See the chickadee? This is a very different view of plants than we usually see. We see a mass of leaves, but from the chickadee's point of view, this must feel like a nice safe place to be.
These rhododendrons outside our living room windows are a favorite place for birds to seek cover.
I'm surprised they choose this because the leaves of the rhododendrons kind of fold up during the winter, so it doesn't (to me anyway) seem to have as good cover as other plants, such as the hemlock (below).
If I were a bird, I'd be inside this hemlock. To me, this seems like good cover, especially with snow adding another level of protection.
A snag tree in the neighborhood
Cavities in dead trees are another important source of cover (in addition to being nesting spaces in the summer).
I don't have any dead trees large enough to have a cavity, but when our sugar maple (Acer saccharum) is finally dead (the arborist gave it ten years a few years ago), I'm going to have it cut to the tallest height that's safe and plant trumpet vines (Campsis radicans) at its base. That should make a green totem with space for cavities.
We installed a roost box many years ago. Note that the entrance hole is at the bottom, unlike nest boxes. Inside there are perches staggered along the side. The idea is that a small flock of birds can crowd into such a space to share warmth. In nature, of course, they'd use tree cavities, but they're in short supply in the suburbs. I have no idea of whether this has been used or not since it's installed at the side of the house we can't see. We put it fairly high up on a pole and haven't been able to get it down—a problem since it should be cleaned. Whether or not this is a useful addition to our habitat I'm not sure.
A place to perch
This flicker was king of the mountain on this tall perch, and this old pear tree is a favorite spot for many birds in our yard.
The more I observe birds, the more I see that they need places to sit, to look for food or for mates, and to declare their territory. How many such places do lawn-dominated landscapes offer?
Grooming feathers is important to keep them in good flying condition. Birds need a good place to sit and do this. These mourning doves are using another favorite perching spot in our yard: the maple tree outside our kitchen window. This lower branch is pretty much dead (although the rest of the tree is healthy). I guess its lack of leaves makes it a good place to perch.
Also one of the top perching places in our yard is this almost-dead pagoda dogwood. Even though it's no longer producing berries, it's nice to know that it's still fulfilling a useful role in our yard. Years ago, we probably would have cut this down, but now with our new perspective we're still able to enjoy it.