If you're a winter Big Bend birder wishing that you had come while the summer sun was still high up in the sky, fear not. Colima Warbler and Varied Bunting may be out of your (seasonal) reach, but there are plenty of other desirable birds to be found in the winter.
The skittish Scaled Quail winters in colossal groups that can number right up into the hundreds in the right areas, and Big Bend is no exception to a Scaled Quail bonanza country, Scaled Quails being particularly common in the desert foothills anywhere in the park. Listen for the distinctive calls of quail flocks and pay attention to the sides of roads, where quails often feed in groups. Scaled Quails are often flushed in large groups. If you see a bunch of birds fly up in a flock that strike you as exceptionally short-winged and fast doves, you've probably just has a sighting of Scaled Quail.
A bird to watch out for in the same habitats as Scaled Quail. Crissal Thrashers are most often seen running on the ground, at least in my experience. Quite a secretive bird, that relies a little bit on luck and in some cases, persistence, to be seen.
The "kukukukukuk" call of Golden-fronted Woodpeckers is usually the first indicator of their presence. Easily found in the cottonwoods of Rio Grande Village, Daniel Ranch and other similar areas with a decent smattering of deciduous trees , the Golden-fronted Woodpecker is found at mid- to upper tree height. Some individuals may be a tad difficult to spot at first, but overall Golden-fronted Woodpeckers are a far stretch from being elusive or shy birds. An almost 100% guarantee for Big Bend birders.
Common locally but otherwise uncommon to rare throughout the park, the Black-crested Titmouse is a bold, noisy bird found in various habitats. In any trails of the juniper-forest Chisos Mountain basins, Black-crested Titmouse are found sporadically. A few riparian areas such as the Windows Trail also have an abundance of titmice. The first indicator to their presence is usually a chickadee-like call, and like most tits, Black-crested Titmice don't take much effort to be spotted.
A hyperabundance of sparrows, in addition to a very high species diversity of sparrows during the winter seasons, make Big Bend an excellent place to hunt for emberizidae. Doubtless, the most common ones are Green-tailed and Canyon Towhee, Rufous-crowned Sparrow, and Black-throated Sparrow, but many other more desirable and rare species are to be found within the park.
An uncommon but regular resident in Big Bend. Watch for the Green Kingfisher along rivers, and that's all I have to say about it, because I didn't see one. Local advice and expertise on the area is probably the best way to find a Green Kingfisher.
Almost 100% guaranteed in the Chisos basin and juniper forest areas, Mexican Jays are a boisterous jay found in large groups, and almost always heard before seen, but easily seen. Even if you don't get the opportunity to hike a Chisos trail, simply slowly driving through the area and watching for jays by the sides of the road is possible.*
Surprisingly uncommon birds
Although definitely present in the park, Chihuahuan Ravens seem to be outnumbered by Common Ravens in Big Bend, so eye each raven you see with a critical eye. Ravens' corvid cousin, American Crow, would be extremely rare in Big Bend.
It's a tough run to see Montezuma Quail during the winter, even in the right habitat, at least in the Big Bend area of Texas. Gambel's Quail, too, are uncommon and not easily seen in the park.
Western Scrub-jay are not easy to see anywhere in the park, although definitely possible.
Coming from the West?
Look for Yellow-bellied Sapsuckers in the juniper woods of Chisos Basin, but watch out for the more common Red-naped Sapsuckers.
Look at every Say's Phoebe you identify more closely: Eastern Phoebes are present, and common, throughout many areas of the park.
Among the many sparrows species of Big Bend are Field Sparrows, which are present in many areas.
Black Vultures are common year-round throughout the park.
Photographer? Almost all areas of Big Bend have amazingly good photography opportunities. Personally, I found the Chisos mountain area and Rio Grande village to have the best photography. Rufous-crowned Sparrows and Greater Roadrunners are particularly tame and easy to get photos of.
Afraid of the heat? It's good that you're not coming during the summer then, but even during the winter, temperatures can climb to incredible heights. Juniper forest areas are much cooler than the rest of the park, and have far more shade. Also be warned that the park is incredibly dry: bring chapstick and lotion.