I’ve just returned from the carwash, where I’ve sat nearly every second day for the past month. I’ve become intimately acquainted with the wash and rinse cycles and even more familiar with how much it hurts when I have to hand over $7 to get grey-looking water sprayed over my hood.

But the expense has been necessary ever since a certain bluebird made a home in one of our birch trees.

It all started four weeks ago when my stepdaughter Gabrielle and I were getting in the car to drive to school. As Gabrielle went to sit down, she couldn’t help but notice a shocking pile of white and brown stains running from the lip of the windowsill down the length of the door.

“That’s one sick bird,” she said, giggling.

Without much thought, I headed to the carwash a few days later and went about my business.

But the next morning, there was the same curtain of poop, one so identical I wondered if maybe the carwash hadn’t done the trick like I thought it had.

So I washed my car again and waited to see what would happen. The next morning, the same thing, except this time there were poop-coated footprints all over the windshield. By this time, this bird, who I can only conclude suffers from extreme irritable bowel syndrome, had started dive-bombing my husband’s car too on his way to mine.

When I brought it up, William let me know he was already deep in investigation mode. He’d even already inspected the tape from our security system’s video cameras to see what was up.

“It’s a bluebird,” he said. “It just seems to love your car. He sits on the windowsill and poops away, almost like he’s been saving it all day until you get home.”

The next evening, as my husband was taking out the trash, he noticed our neighbor wrapping plastic bags around his truck’s side-view mirrors.

“You too?” William called over to him.

“Unbelievable,” the neighbor called back.

After some brief research, we decided to buy a plastic owl, whose predatory nature is supposed to scare other birds away. As Gabrielle and I shopped in Lexington, William went to the local Lowe’s to pick up one of these specimens.

When, fresh and light off our spree, I walked through the door, I jumped back in fear when I saw the owl, which was staring at me from atop the kitchen island. When Gabrielle walked in carrying her bags, she likewise yelped.

Its eyes were mean and yellow, and it sat there looking hungry and irritable. If I were a bird, I’d hightail it out of there.

So on Sunday William hung it in a tree, and we waited to see what would happen. Four hours later, the car was still spotless, and we thought victory was at hand.

But the next morning, my car had been so blasted it looked like it had spent a week inside an aviary. There were poopy footprints all over the windshield, roof and hood, not to mention the waterfall of droppings on both windowsills.

“It’s almost like the owl made him angry — or more crampy,” William said, shaking his head.

He walked outside with a pail of soapy water and sponge. He said nothing when he came back inside except to utter, “Impressive.”

Now, as my carwash bill continues to mount, we are considering buying plastic snakes as our new scare tactic. I’ve also noticed William eyeing the BB gun with sudden affection. Honestly, though I love animals, I’m willing to make a donation to the Audubon Society in exchange for the life of this enemy bird. The problem is: How do you shoot it without hitting the car by accident?

Speaking of my little vehicle, I see it now outside, cowering more than sitting, helpless, armless, so very dirty. It can’t go in the garage because it doesn’t have a spot. It just has to sit there and wait. From deep within the birch trees, I can hear the bluebird laughing — and eating.