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.
Source: SanDiegoRegionBirding Latest Reports