Beyond the short walks, hiking and backcountry options are endless. If you go off trail, wear proper gear, carry adequate supplies, use a topographic map, and know your route. Get advice on routes and gear from any park ranger or at park headquarters or any ranger station. It is important that you inform someone, preferably a park ranger, of your intended route. A backcountry permit is required whenever you plan to camp overnight anywhere but in developed campgrounds. Backcountry permits are issued free at park information and orientation points (see map). Take it easy on the trails and enjoy yourself, especially until you are acclimated. In the mountains, the elevation adds to the exertion. In the lowlands the heat is an important factor. Birding To learn about the raven, writes Barry Lopez in _Desert Notes_, “bury yourself in the desert so that you have a commanding view of the high basalt cliffs where he lives. Let only your eyes protrude. Do not blink—the movement will alert the raven to your continued presence ... there will be at least one bird who will find you. He will see your eyes staring up out of the desert floor. The raven is cautious, but he is thorough. He will sense your peaceful intentions. Let him have the first word. Be careful: he will tell you he knows nothing.” The raven is one of more than 400 species of birds that have been seen in Big Bend National Park. Why so many? The park lies right smack on the flyway for birds winging north out of Mexico and, indeed, almost three-fourths of the species recorded in the park fly right on through. But for serious birders—even those less determined than the raven seeker Lopez describes—this is paradise. During the spring migration northbound birds confront the northwest-southeast trending Sierra del Carmen. Instead of flying over them, most birds keep to the west and are funneled right into the park. For the return trip in fall, however, the Sierra del Carmen have the opposite effect. Many southbound birds peel off east at Persimmon Gap. The fall migration is smaller and brings more lowland than mountain species. The springtime bursts of birdsong are inspired by the drive to claim territory, as some 100 species nest within the park. Many of these breeding birds will abandon the lowlands as soon as their young are big enough, moving to the mountains to beat the heat. Rio Grande Village, for example, is at its low ebb for birdlife in July, and in the Chisos Basin you will find yourself identifying lowland birds left and right! But all in all, Rio Grande Village, with its ponds, cottonwood groves, rich riverbottoms, heavy brushlands, and neighboring desert, is the best year-round birding site in the park. In the springtime it offers an unbelievable display of species.