CASCO BAY, MAINE. — Casco Bay, Maine.-- I am in the bushes, digging out the bittersweet vines wrapped murderously around a tree, when the cardinal comes back into view. He flies in all his finery across the lawn, undulating in great long crimson loops. And then ends his elegant flight pattern by crashing directly into the barn window.
Mission accomplished, he retreats to a nearby bush. From this launching pad, he commences his afternoon of battering. The bird I have come to call Knocko attacks the glass once, twice, a dozen times, before he takes off to fight another time.
I have been watching this routine for weeks. The first time I saw him perform his Great Window Crash, I felt like the audience at an air show when the careful choreography of the planes suddenly turns into a mid-air collision.
Like any guilt-ridden eco-worrier, I assumed that it was my fault. Last year some cardinals had nested inside the barn; this year, we replaced the window. Was the bird trying merely to get home through the pane?
But as Knocko went another and then another round with the window, it occurred to me that he must be fighting. With his own mirror-image.
Did this splendid and bird-brained creature see an enemy in the reflection of the window pane? Did he come out attacking -- day three, round twelve -- an imagined rival? Himself?
Watching Knocko knock out his brains and aware that I am no naturalist, I call the Audubon Society where a field ornithologist confirms my own mischievous diagnosis of Knocko's behavior. The cause, in one word, admits Simon Perkins, is testosterone.
At this time of year, Mr. Perkins tells me, males often smash themselves against windows, hubcaps, even rear-view mirrors. ''What they see in their reflection is an intruder in their territory and they attack it. They won't give up as long as their hormone level is up.''
Lest he be guilty of stereotypes -- politically incorrect for those of us who deal higher up on the food chain -- Mr. Perkins adds that occasionally a female will do it as well. But by and large, banging your head against a mirrored wall is a male activity. Testosterone, he adds traitorously to his sex, ''is a universal hormone that makes all males do very strange things.''
This sort of behavior, built into their systems long before there were windows or hubcaps in the world, is now entirely unfit for the rigors and traps of modern civilization. ''Even if they don't injure or blow themselves out immediately, they only have a certain amount of energy in their short lives,'' says Mr. Perkins. ''It's like a gas tank. What you use now you won't have later.''
Knocko and his like not only harm themselves, but their families. ''Raising young is an extremely expensive task. To have to expend more energy on an imagined foe is,'' he says conclusively, ''not good.''
Simon Perkins is no sociobiologist. Nor am I. Leaping from birds to humans or from cardinals to generals is a risky business. Furthermore, neither of us wants to be accused of male-bashing. After all, the cardinal is doing quite enough male-bashing for both of us.
But this week at least, even in Knocko's territory, people are asking whether George Bush's decision to fight in the Gulf was the product of thought or a hyperactive thyroid. So we're entitled to worry a bit about nature, nurture and warfare.
In the aftermath of the Cold War as well, some are wondering if Russia was ever a real threat. Which of today's enemies is a figment of our imagination? A mirror image?
And while we are on the subject, it isn't just ornithologists who notice that ''raising young is an extremely expensive task.'' Nor is it just environmentalists calculating how much money has gone to fool's fights instead of children. The task of separating real and false foes is a central one for any life built on instinct but dependent on reason.
Ah, but for Knocko at least, there is good news, a cure. The man from Audubon tells me that my cardinal's hormone level will be down in another week or two. In the meantime I am instructed to cover the window. With one blanket, carefully placed, I can wipe out an enemy and save a small friend.
What is this? Think globally, act locally? Today, with a punch-drunk cardinal at my window, he makes it sound so easy.
Ellen Goodman is a syndicated columnist.