While walking the back side of Blue Hill Trail in Sherburne NWR (near Princeton, MN), heard a completely unfamiliar song. The song was quite loud (stop you in the middle of a trail loud, although 25 yards away), medium pitch, five notes followed by a bit of a rolling ending. I would describe it as wah-weet-weet-wah-whir, with pronounced emphasis on the two weet-weet portions (much lower & somewhat slower than a shorebird's weet-weet).
The songs came in two pairs of two verbalizations each, initially sounding very near the ground, then at mid-canopy. The area is oak savanna, relatively open woods & grasslands, with the sound initially occuring 3-5 feet into the woods. Twenty minutes of pant-staining search through brush yielded nothing. The loudness & pitch was very close to a Carolina Wren, although I'm only familiar with its "churry-churry-churry" call. I could not make a determination from Sibley whether it may have been a CW alternate verbalization (which is all I have in the car). Help! Al Schirmacher Princeton, MN Mille Lacs & Sherburne Counties