When a tree dies, its role in the ecosystem changes, but it is still a home. Some bird species utilize dead trees. A dead tree is bird habitat, and habitat for hundreds of other species, especially fungi and insects, that are specialized feeders on dead wood. I've written about dead wood as habitat in a previous post on click beetles.
In my lifetime I've seen many dead trees cut down for the sole reason that they were ugly or unsightly. Sometimes a dead tree poses a hazard to people, and in that case it should come down.
I took the photographs above on 14 June, and posted the top one on Twitter shortly after. I observed the male red-bellied woodpecker drumming just before I took the photo (top). There were multiple snags. The pair of flickers (below) were engaged in courtship. Yes, these are common species, but they are beautiful nonetheless. They have value.
About a week later I discovered that the snags had been cut down and removed. It is possible they were determined to be a hazard to people, but I doubt it, given the location and the project going on. Even if they were deemed a hazard, could the design have been altered to keep the people and the other species' homes safe?
If a tree must be cut down, don't remove it. Leave it on the ground, if possible. But please try to keep dead trees standing by designing people-spaces around them. Let dead trees be. They are home for other species.