In her fourth-floor apartment in central Rome, Emanuela Tripi awoke at dawn to the terrifying sounds of a home invasion. She crept into her kitchen and spotted the culprit — long white neck, red-rimmed eyes, yellow-webbed feet — stabbing its beak into a garbage bag.

Growing up in Sicily, Ms. Tripi always had a romantic vision of sea gulls, but now she was face to face with a predator that has aggressively colonized a city a good 20 miles from the sea. She threw a slipper. It ignored her. She lifted a second slipper. It cawed violently, took flight and charged.

“Arrivederci, you win,” she thought as she ran out of the kitchen, closing the door behind her.

As her cat cowered, wetting the couch, she banged on the door to scare off a bird she described as “enormous, above my knee, as big as an American wild turkey.” But it stayed “like it was its place” she said, until it was done eating and flew back out the window.

Romans have for years bemoaned the degradation of their city: the potholes, the burning buses, the unkempt parks and the uncollected garbage, stinking its streets and clogging its river.