If you are a birder and are going to South Texas from New Mexico via I-10, try to spend a night or two just off I-10 at South Llano River State Park in Junction. The campground is near the river and shaded by oaks and pecans. A short walk from the campground is a bird blind with running water and an assortment of feeders. We saw more than a dozen species at the blind, some of which we had not seen previously. Several were Mexico natives that had wandered north when we were there in mid-winter.
PS--Are you planning to stop at Bosque del Apache when you are going through New Mexico? The cranes and snow geese will be there by the time you are there, so don't miss the dawn flyout. It is spectacular!