My friends John Kistner and Sara Waters found these birds in their yard in Tacoma and sent out the pictures to some friends. In the ensuing e-mail thread, a dedicated bird-watcher identified them as Helmeted Guineafowls, native to Africa. According to Wikipedia, when the birds first introduced to North America, people confused them with Wild Turkeys. (The way to tell them apart: Guineafowls don't share a name with a bourbon that will make you really sick if you pound it on a hot day, using warm Gatorade and beer as chasers. And no, I never tried that.)
Rob Faucett, the collections manager at the Burke Museum's Ornithology Division, says that a Helmeted Guineafowl sightings are "extremely rare" in this region. "They're native to Central Africa; if I looked for one in Seattle for two months, I probably still couldn't find one." He suggested that they likely escaped from the zoo or from a rare bird collector. The Point Defiance Zoo says it hasn't lost any Helmeted Guineafowls lately.