I feel really lucky to have stumbled on this nest. Female was alternately foraging to feed nestlings and then brooding them, so they must still be quite young. Nest was well-hidden in a huisache tree.
This is a banded bird. I found a banded shrike using the same perches at this lake on March 1 of this year. The bands here match, except that one band is missing on this bird from the right leg. Either this bird has chewed it off, or this is a different same-study bird that maybe has mated with the March 1 bird? Never heard back from USGS on the first bird, but will report this one just in case it's a separate individual.