Mar 31, Spring Creek 100 ft away giving sit sit in flight. He sang from a branch there, then disappeared. Then sit sit in flight as 2 titmice flew N across road and foraged in small meaquites. They moved N out of my sight. I moved across the road to two small post oaks, due W of the suspected nest tree. No titmouse activity until 8:13 when I heard 'swh dub dub' call SW of me. At 8:14 a movement and I saw a titmouse fly into the E tree - it moved toward the central crotch by degrees and entered a cavity there. Then I heard song peer -- -- but couldn't see singer. At 8:17 same song from W toward the creek. WIND STRONGER to 8-10 mph. The next site tree was in an L shaped clump of 2 post oaks and 2 blackjacks, being the apex tree. It is about equi-distant from creek and windwill and I'll refer to it as the 'windwill nest' hereafter. I walked S for 15 minutes, approaching a treeless deep cut portion of the creek. I turned west, then heard song kick-kick-kick -- -- (in 5a and 6a) and located singer at 8:40 in a live oak 40 ft high - bird sang same song (clearer peer -- once). I watched him in binoculars, definitely a black-crested type with forehead whitish. His song continued until 8:46 by which time he had moved to the E part of that large tree - notes sit sit sit either from that part of the oak or from farther E seemed to be from a second bird (titmouse?). The singer moved E to an oak 20 yards away I believe and continued song. There were plaintive sit sit notes