jaimejcoon's Identifications

Baby dickcissels! These babies are going to be banded for population and habitat data by painted bunting researchers. Please never disturb bird nests if you come upon them, this photo was taken for research purposes.

This was a bit surprising. I believe this is a tree frog of one species or another, but my available references don't show any species tree frogs native to Iowa. What am I missing? Where have I gone off track?
Ph. on the Timberhill Savanna (private).