A prothonotary is a clerk in certain courts of law.Apparently some of them wore
bright yellow robes hence name for warbler. This bird became famous (as I recall) because when Alger Hiss was tried and convicted of treason, he claimed he
was down in Virginia looking for Prothonotary Warbler when Whittaker Chambers
claimed that he passed him some secret documents. Nixon,I think, was prosecutor.
Many years ago, when i worked in Washington D.C., some local birders told me
this story. Clark Blake, Dept.of geology,WWU.