Buff-breasted Sandpiper, here is what I saw on departure.

about 6 of us were still on the bird when suddenly, a Kestrel, chasing a Red-tailed made the Red-tailed dive really low right above the Sandpiper.  The bird flushed, flew straight east, about the Commital Shelter area and then I saw it suddenly drop, but one or two others said they saw it fly north.  We went and were never able to re-find it.  

Mark Stratton

North Park