If you live in Montgomery County and make a habit of feeding the birds during the winter months, you may be helping swell the county's rat population. That's the bad news from Glenn Bransford, one of the county's two health inspectors who specializes in vermin control.

Montgomery County's affluence, which allows bird lovers to indulge their feathered friends, has led to a rat population estimated a couple of years ago at two rats per resident. And Bransford says pet owners who feed their dogs outside are the next most common troublemakers, though bird feeders are by far the biggest problem.

"We did a survey for 18 months several years ago," says Bransford. "In every case of rat infestation, we tried to establish the food source. Better than 70 percent was due to people feeding birds. If you watch birds, they knock a dozen seeds to the ground, and you don't have that many ground-feeders except starlings to clean them up. So the rats find they have a permanent source of food and move right in."

Footnote: Bransford offers citizens a diagram of a rat-proof birdfeeder that is essentially an upturned garbage can lid. And he recommends pets be fed inside, garbage be well covered and, at commercial food establishments, that the drain plugs be keep in dumpsters to keep rodents from having access to bulk trash.