According to the millions of tiny little thermometers out there flying around, taking the temperature of the land, the earth's health is not so good.

Songbirds are one of Mother Nature's monitors. How well they are doing says a lot about how well the land is.

And bird-watching groups are reporting steady declines in bird populations.

No one knows for sure why. It could be poor habitat, weather, encroachment, food supply, diseases, predators or a combination of any or all these factors.

Whatever the reason or reasons, the country's songbird population is declining.

And it's not species specific, said Russ Norvell, Utah partners in flight coordinator for the Division of Wildlife Resources.

"Here in Utah," he said, "we're looking at a relatively steady decline in the riparian bird population. We're not singling out one species but seeing an overall decline statewide."

The decline is also being reported across the continent.

Results from the 12th annual Great Backyard Bird Count, held in February, showed: "The count continues to show declines in some common birds, especially grassland and shrubland species."

The Audubon Society recently cited data from its century-old Christmas Bird Count in California and the Breeding Bird Survey conducted by the U.S. Geological Survey. The report said: "Population declines of some of the most recognized and beloved birds in California echo the disturbing findings of a new analysis by the National Audubon Society that reveals how local, national and global threats are combining to take a toll on birds, habitat and the environment across the country."

A Canadian study said: "Land birds ... representing about 220 species of birds, have shown long-term declines over the last 30 years. Loss and degradation of wildlife habitat are believed to be the primary causes of these declines."

Songbirds are a migratory bird. They fly thousands of miles from Utah to wintering areas in Mexico and South America and fly back in the spring — many times to the exact same location, occasionally back to the same nest.

Utah has been involved in a songbird study for the past 15 years, roughly eight years longer than any of its neighboring states.

Norvell said the DWR set out with concerns in 1992, "that our lowland riparian habitat was the most likely area to be in trouble, so that's where we focused our efforts.

"What we'd like to see is more of a commitment to long-term monitoring from neighboring states. They are relying on us now because we have the longest-running monitoring program."