I live in West Texas. I’m not a native but a Northern Yankee transplanted by way of other parts out west. Texas is quite a big state, when you run across a native Texan who acknowledges not being familiar with parts other than his home turf, he has a saying; “I haven’t been beyond the fence.”
That said, I haven’t been beyond the fence. San Angelo is the farthest north and west, Big Bend National Park the farthest southwest, that’s it for my personal knowledge of the state.
However, I’ve been scouring the net for the past few weeks researching/planning a spring trip to the lower Rio Grande Valley. In doing so I ran across your post. It’s been a few weeks and I’ve been back to the thread a few time hoping someone would chime in, giving you and me both something to work with. Well, we got zip so I figured I better register/join the forum with the hopes of enticing others lurkers to step up and contribute something…..anything to the topic.
As for your drive south from Houston, Texas Parks & Wildlife has what appears to be a great selection of driving maps (on-line accessible) outlining the route, stops, and birds you’re likely to see.
Here’s the link to The Great Texas Wildlife Trails.
Here’s the link to The Great Texas Costal Birding Trails.
Here’s the link to the Central Texas Coast.
Here’s the link to the Lower Texas Coast.
The
Upper Texas Coast doesn’t seem like it has a lot to offer by way of density but the map includes Houston so it's here for that reason.
The maps are self-explanatory; on the left side of the page click on the “Loop” and up pops the driving directions along with birds you’re likely to encounter.
Dig out a Texas map, plan out your drive south, and program your gps or the car’s gps.
That’s it, nothing left to do but keep your head up and your glass ready.
Hope this helped.
PM or post if you have questions or need me for anything…..all I ask is a report on the birding and on how the trip went.
Good Luck…!!