Yellow cat up to 45 kilos (100 pounds) have been taken from the river, and 14-kilo (30-pound) cats are not uncommon. Channel and blue cats also provide fine sport and good eating. These deepwater species feed on aquatic plants, insects, and smaller fish, both living and dead. They spawn in depressions and sheltered nooks in river banks and canyon cliffs. While catfish account for most of the recreational fishing in the Rio, many other interesting species swim the brown waters: the predatory garfish, needlenosed and shaped like a torpedo; the humpbacked carp that can survive even in limited waters; smallmouth buffalo, sheepshead, and green sunfish; the bullhead that favors quiet waters and can endure higher temperatures and lower oxygen content than most other fish; and of course the minnows, as plentiful and gregarious as sparrows, with a preference for running water and rocky or sandy bottoms. Tips for Desert Travelers Best Times to Visit Big Bend. Winter days will be nippy in Big Bend’s mountains and comfortably warm in the lowlands. Snow falls in the mountains once or twice a year. Spring hits the desert lowlands in February and begins a slow ascent up the mountain heights, arriving in May. Some of the desert plants bloom throughout the year, but the most predictable displays are in springtime. Summer is problematic. If you come in the summer you will probably want to take to the mountains. Midsummer daytime temperatures in the desert and river valley generally hover above 38°C (100°F)—often well above. But up in the Basin, daytime temperatures average 29°C (85°F) and nights are cool. Autumn is usually sunny, with the air gentle and warm. The best months for running the river are November through February, both for river conditions and for avoiding summer’s intense heat in the canyons. Climbing Hazards. The character of the basic rock in the park is very unstable, making it unsafe for climbing. Climbing is not recommended. Night Driving. Be extra alert for wildlife while you are driving at night. Many creatures, particularly deer, may be blinded by your headlights so that they make no effort to get off the road. Spines and Thorns. Beware the cactus and other spine- and thorn-bearing plants, shrubs, and trees. These can inflict painful injury. To protect yourself, wear stout shoes and tough clothing if you go hiking off the developed trails. If you go out at night, walk carefully, carry a flashlight, and don’t venture out too far. The National Park Service recommends that you carry tweezers for removing irritating spines, which may be too small to extract with your fingers. People have even gotten mouthfuls of delicate—but highly irritating—spines of some pricklypear cactus species while trying to eat the fruits! Delicate spines hardly noticeable to the naked eye can inflict painful injury.