I'm guessing that the one whooper confirmed at the Platte River in Nebraska
on March 4 is the whooper that wintered north of the refuge,
last seen at Brazos Bend State Park SW of Houston on February 8. It's too early for whoopers wintering at Aransas to be in Nebraska.
Date: Fri, 12 Mar 1999 17:53:51 -0700
Basically all (or nearly all) whoopers still at Aransas. The two ultralight whoopers at Bosque del Apache are believed to have started the migration the morning of March 12.