Occasional visitors during the winter months, with several sightings from late-October through late-January.  A few additional sightings in March may be of migrating birds from further south.  Swan identification is difficult, especially of silent birds flying high overhead  (typical), so in many cases we've been unable to identify our swan sightings to species.

A lone swan near the lake platform on 2008-05-01 was certainly out of season.  It was viewed from too far away to get to species, but the few other King County swan sightings that I am aware of were Trumpters.