Yesterday, I wrote about science's inability to explain the attraction some women feel for monsters. Fictional monsters. After posting, I learned that a real-life monster with whom I had an intense, long-term relationship just died. His name was Zach, and he was a parrot, a yellow-collared macaw.

I bought Zach in 1990, when he was a fledgling, to console my wife after the death of her dog, the love of her life. Zach was a noisy little bully, who enjoyed terrorizing humans. He had a perch in the kitchen, loaded with toys and dishes for food and water, but he roamed the house freely, causing trouble.

He liked to hide under an upholstered chair in our living room, waiting for bare-foot prey to pass. He'd dart out, bite the feet or ankles of his victim, and scuttle back under the chair's skirt, cackling maniacally. When he laughed, Zach was probably imitating me and my wife, who found his antics hilarious. But I don't doubt that he took genuine, sadistic pleasure at inflicting pain.

With some targets, especially blond-haired women, toward whom he was insanely hostile, his aggression was more direct. Wings flapping and beak gaping, he dive-bombed his terrified target, landed on her upper back and gnashed her neck. His bites could draw blood.

My wife finally, reluctantly, had Zach's wings clipped to protect visitors. Sometimes, if a blond entered the kitchen, he still launched himself at her, landing with a thump on the floor, and chased her on foot.

Zach was, for years, as loving toward me as he was vicious toward others. When I came home from work, he welcomed me by bobbing his head and screaming "Hello!," his pupils repeatedly dilating and contracting. Then he fluttered his wings, indicating that he wanted me to pick him up.

When I did so, he burrowed under my shirt and nestled against my chest, producing a purring noise by grinding his beak. When I walked around the house, he poked his head out above my collar to scope out the scene, and I had this weird sensation that I was a big, dumb machine and he was piloting me. Which probably wasn't far from the truth.

He also liked to crawl onto my shoulder and nibble my ear, emitting murmurs of affection. With a forefinger, I'd ruffle his gold and emerald neck feathers, which would fan out like fur, as his eyelids slid shut dreamily. Now and then, with no warning, he'd interrupt our reverie by screaming in my ear or biting the hell out of my earlobe. He also crapped on my shirts and chewed tiny holes in them, defying my commands to stop.

When my son Mac was seven or eight, Zach dumped me for him, just like that, with no warning or explanation. If I approached Mac while Zach was on his shoulder, Zach lunged at me, snapping his beak.

When my wife and I got divorced, Zach stayed with her, so I haven't seen him much over the last five years. Life was easier, calmer, quieter without him. But when I called my kids at home and heard Zach shrieking "Hello!" in the background, I missed him.

Zach was a monster, who drove me crazy, but I loved him, and I'm sad he's gone. Explain that, evolutionary psychology.