Still sorting through my photographs from Houston, I was trying to identify these birds that were feeding on the grass at Paul D Rushing Nature Reserve. Of course, they kept such a distance that a decent photograph was difficult, although you can see the key features from these.
To European eyes it looked like some sort of bunting or sparrow. Consulting Wikipedia, it seems that American Sparrows are not quite what I had thought.
Although they share the name sparrow, American sparrows are more closely related to Old World buntings than they are to the Old World sparrows (family Passeridae). American sparrows are also similar in both appearance and habit to finches, with which they sometimes used to be classified.
So it’s some sort of American Sparrow, of which there is a huge proliferation, according to Wiki. A song sparrow is a likely possibility, as these certainly over-winter in Texas (it was March).