Several years ago, I heard Bill Berg, the longtime Minnesota Department of Natural Resources wildlife biologist, describe his job as thus: "I count things." Fish, wolves, grouse — you name it, if it was a species of interest and lived in the north woods, Berg counted it.

One of the places I keep tabs on as a journalist working on environmental issues also counts things — animal, bird and fish fatalities — and can be an important source of information in an avian flu-worried world. It's the U.S. Geological Survey's National Wildlife Health Center. I think of it as an early warning system, especially when remembering the 1918 influenza outbreak that began with birds and migrated to humans.

Then, of course, there is the worry of every livestock farmer: Diseases that may not affect humans can certainly be devastating to a herd or a flock.

Other times, goofy stuff happens. That was the case recently when I looked into a report about a large number of common yellow-throated warblers in Chippewa County.

About 40 to 50 of the little songbirds, which are more familiar in the southeastern states, were found dead in the parking lot of a local business in Montevideo. No disease killed these birds, however. They died of "blunt trauma," just like many of the victims on a "CSI" show.

Was there a bird-hating scofflaw on the loose in Montevideo? Someone running around with a tennis racket or baseball bat thwacking warblers?

No. The culprits were heavy fog and power lines or a tall building.

"We're not sure of what exact structure they hit since we don't have a first-hand account of anyone seeing the birds hit anything," LeAnn White, a USGS wildlife disease specialist in Madison, Wis., told me.

The birds were in "good nutritional body condition," she said, so worries of a virus wiping out a flock of the little migrators went away.

"Injuries and mortalities in wild birds caused by impacts with buildings, wires, or other structures are not uncommon," she added.

Not all the animal and bird deaths reported to the USGS are so innocuous. Investigators examined several dead Canada geese near Wadena in November and found the parasite (Sphaeridiotrema globulus) that killed them. (The birds get this parasite from eating snails; there are no reports of this parasite infecting humans.) The same parasite and two others were discovered in about 150 dead lesser scaup and American coot in Itasca County a few weeks earlier, as well as in nearly 1,000 dead scaup, coot and blue-winged teal in Houston County at the start of the fall migration.

The USGA issues quarterly reports dating back to 1995 here.

In one of my recent most-favorite understatements, White said those warblers "[ran] into an object that they normally could have avoided."