Many bird populations are on a glide path toward extinction, and because the flocks are an environmental warning system, that's not good news. Not for birds, not for people.

But not all of the news is bad, so cheer up and pay attention. The efforts to preserve puddles and wetlands for ducks and other waterfowl are helping those birds to recover. If people make similar efforts to rescue the homes of other bird species, cut back pesticides and pollutants and help control invasive plants, other kinds of birds also could come back.

There are things we all can do, like keeping cats indoors. Whiskers and Muffin and Tiger all like to hunt birds, and if the cats go native, that is, feral, they become even more deadly killers of birds.

According to the first comprehensive study of bird populations in the United States, a third of the nation's 800 bird species are declining. People are the reason, though the report couches the major causes in terms such as habitat loss and invasive species. There are other threats as well, including industrial pollutants and the many glass windows that we humans have erected. Birds fly into them and die.

In the Great Basin, unplanned urban sprawl is by far the greatest villain in the dead bird story, according to the report. You can blame developers out to feather their own nests, but governments play a role by encouraging soaring growth. Some of the fastest-growing urban areas in the nation are right here in Utah. Humans are not only fouling our own nests, we're destroying the nests of others. To reverse this, the study recommends a regional system of protected areas.

Poorly planned energy development, which tears up delicate habitat on arid lands that are slow to recover, kills birds. So does unsustainable grazing on vast stretches of public lands. This environmental destruction gives invasive plant species a leg up. The invaders displace the plants that grow the seeds that birds rely on for food. Another invader, cheatgrass, fuels wildfires that destroy sage that supports birds.

However, if Utahns and other Americans shoot down urban sprawl in favor of smart growth, thereby disturbing less land and improving air quality (because we will have to drive less), the birds should benefit, too. If we set out to preserve or restore wetlands or forest, all creatures will be better off, including us. What is life, after all, without bird song?

In some cases, our environmental policies already are headed in the right direction, but we need to do more. The bird study is telling us that time is not on our side.