The Winter Wren scolds, "chak-chak, chak-chak," from the brush pile. Unless you know wrens, you might be surprised that this tiny, compact bird has a very expansive song. Although they're usually seen fussing around close the ground (as above), they will sing from a branch several meters up, pivoting left and right to broadcast their song throughout the forest. This also has the effect of making the source very hard to pinpoint.
Update: It appears that this is no longer a Winter Wren. The Pacific coastal form is now known as the Pacific Wren, Troglodytes pacificus. Reasons for the split given here. Thanks to Neil for the info and link. Oh, and tick!