Ask Mr. Smarty Plants

Cercis canadensis var. texensis (Texas redbud) and Quercus polymorpha (netleaf white oak), also known by the common name Monterrey Oak, are both native to Texas and good choices for Austin. However, insects don't care much about where a tree came from.

This Iowa State University Extension website Sustainable Urban Landscapes gives an excellent analysis of Diagnosing the Problem with pictures of the symptoms a tree might exhibit. Holes or chewed edges on the leaves of outdoor plants are generally caused by grasshoppers, crickets or caterpillars. We realize you have not seen the insects, but crickets and grasshoppers would certainly be candidates for hit and run charges. Another possibility, although we feel you would have noticed this, too, is the leafcutter ant. Please read this previous Mr. Smarty Plants answer which goes into considerable detail on this little creature.

From Top Turf, we found this website Insect Damage with some good pictures of insects and the damage they do to leaves. 

In the final analysis, we are gardeners, not entomologists. We are sure you realize that in the very difficult summer we are having in Austin, with drought and record heat, conditions are probably not normal. Insects that might ordinarily not disturb you could be forced to invade your trees. The trees could themselves be demonstrating stress with the leaf damage. The people at the Travis County Extension Office are more likely to have up to the minute information on what is damaging plants in the area, as well as something to do about it. The website we have linked you to has contact information, and may, indeed, have information on the site itself on what is chewing on trees this season.