I am reading a 1984 species list that Fred Sharpe put together for the
Anacortes Ferry termial area. He includes general notes on seasonal
distribution, abundance, and habitat for most specis, but writes TBE for
6: green-backed heron, American bittern, SB dowitcher, Caspian tern,
mountain chickadee, and rb sasucker ("TBE in winter"). All the other
notes are written out, but no comment on the meaning of TBE. H'm!