Nobody ventures into this soggy wetland on the edge of Mission on the Umatilla Indian Reservation after dark when the shrieks begin. Resident Sylvia Minthorn once thought about plunging in to find the source of the cries. "I used to play back there when I was a kid," she says. "But then I thought, 'What if I do find something? Then what am I going to do?' " Richard Cockle/The Oregonian PENDLETON -- Baby foxes or
Bigfoot?

The eerie late-night serenades began in November and emanate from a brushy swamp on the
Umatilla Indian Reservation east of Pendleton. The cries range from high-pitched screams to basso profundo roars.
"It's causing an uproar around here," said Sylvia Minthorn, who lives in a tribal housing unit near the swamp, where she used to play as a child.
She's seen grown men's hair stand on end when the shrieks commence.
Colleen Chance, a tribal housing authority employee, keeps a recording of the howls on her iPhone.
"It's kind of spooky," she said. "Some say it's foxes, some say it's a female coyote and some say it's Sasquatch. I don't know what it is."
Listen:
So far no one's pinpointed the source of the noise on this rugged 178,000-acre reservation that extends into northeastern Oregon's Blue Mountains