Have you noticed any large, mysterious birds around town?

There’s an ominous presence on the west side of town these days.

With their dark underbellies blocking the evening sun, their graceful glide and dive patterns mimicking the aerial ballet of a barnstormer, and their massive wing spans establishing their rightful place atop the pecking order, a dozen or so large birds are putting on quite an air show.

If you live anywhere within a mile of Yowell Meadow Park, you may have seen them. It’s hard to tell what exactly we’re looking at, but we know it’s extraordinary.

I called my friend Daphne Ryczko, owner of the Purple Parrot on Davis Street, last Friday morning to discuss the phenomenon. We went through a checklist of the usual suspects:

n Turkey buzzards seemed most likely, but these birds were flying extremely low and perching in the tree tops. Besides there’s no mistaking that face that only a mother turkey buzzard could love.
n The size and coloring of the birds indicated hawks or juvenile bald eagles (who don’t yet have their distinctive white heads), but the sheer numbers seemed to rule them out.

n Finally we settled on ravens. Actually we guessed ravens, and I was sent back to do more surveillance.

So I went outside to see if I’d get lucky and they’d be out hunting. I spotted a nest in a tree and looked for another, but no birds. Until ... I turned around and there, perched on a low tree limb not 20 feet away, was a Cooper’s Hawk (best guess) staring at the bird feeder across the driveway.

It’s hard to describe the rush you get when you see a hawk that close. I called Daphne back, knowing she’d appreciate the feeling. It’s awe-inspiring. Unfortunately the mysterious bird invasion remains a mystery, but the investigation has gotten exhilarating.

Moments like that are a reminder that nature’s most exciting programs aren’t on television. This President’s Day weekend, pull the kids off the couch and have them sit in the yard, or by the window, for at least 15 minutes counting and identifying the birds they see. It’s a nice break on a school holiday, and it’s for a good cause —  the 13th annual Great Backyard Bird Count.

“The GBBC is a perfect first step toward the sort of intensive monitoring needed to discover how birds are responding to environmental change,” said Janis Dickinson, director of citizen science at the Cornell Lab or Ornithology. “There is only one way — citizen science — to gather data on private lands where people live.”

Researchers at Cornell, the National Audobon Society, and Bird Studies Canada, use the data sent in by bird watchers to aid in their efforts. Last year tens of thousands of participants helped create what organizers dubbed “the continent’s largest instantaneous snapshot of bird populations ever recorded.”

For those interested, visit birdcount.org. All are welcome to participate, and the Web site is loaded with tools to help you identify unfamiliar species and special materials for educators to share the project with their classes.

And if you’re looking for a way to attract more song birds to your own yard this winter, visit Daphne at the Purple Parrot and she’ll get you started in a heart-warming hobby for the coldest of days.

Clements’ column runs every Monday.