The homeowners, who kept 29 white chickens in a backyard coop, discovered the headless carcasses when they went out Monday morning to feed their birds, The Anchorage Daily News reported.
"They were very concerned as to why somebody would do it, and kind of spooked," State Trooper Ken Vanspronsen said.
A police spokeswoman said the carcasses were laid out in a straight line with a circle of dead birds at one end, in a "lollipop" pattern.
"It's kind of a mystery as to why somebody would tear off chicken heads and then arrange the bodies in a linear pattern," Megan Peters said. "It's certainly something that is perplexing. ... It's unsettling, to say the least."
Authorities would not name the homeowners, saying they didn't know if the incident was meant as a threat against them or just simple vandalism, the Daily News reported.