Black-hooded snake
Bullsnake
Two Non-Drinkers
The kangaroo rat and roadrunner exemplify adaptations for desert living. Neither drinks water, as a rule. The roadrunner gets its moisture largely from its omnivorous diet, which includes lizards and small rattlesnakes. It kills them with stunning blows of its beak. Its characteristic X-track provides good traction in sand. Agile and nimble, this 60-centimeter- (2-foot) long bird can fly, but it prefers to run, at up to 32 kph (20 mph). Mexicans call the roadrunner paisano, “fellow countryman.”
The kangaroo rat metabolizes both energy and moisture from seeds that contain less than 4 percent water. It has no sweat glands and cools itself by breathing. Its nasal passages, cooler than the rest of its body, condense breath moisture for retention. Its kidneys, among the most efficient in the animal world, excrete uric wastes as a concentrated paste, not as liquid, saving further precious water. Its deep burrow has a year-round relative humidity between 30 and 50 percent. These rodents sometimes fight with each other, leaping high into the air and striking at each other with their strong hind legs.
You can see the nighthawk now against the pale and pearly afterlight, and a star pops out, then another and another. Suddenly, more stars seem to be twinkling than can possibly exist in the universe. In the absence of man-made light they are an overwhelming presence. The Milky Way stretches from horizon to horizon. Who can believe that our Sun is just a middle-sized star, and planet Earth a mere speck spinning on the fringes of that gorgeous luminosity?
On a night of no moon, in the mist of starlight, the mule deer may stay active until dawn. On mild, windless nights the hunters and the hunted come out in full force: insect-eating scorpions, tarantulas, and wolf spiders; seed-eating pocket mice and kangaroo rats; rodent-eating snakes, badgers, and owls. What a hurrying and scurrying, what popping up from holes and burrows, what slithering and digging, what squeaks and shrieks, what patient waiting in ambush. And by what ingenious means do the hunters find the hunted in the dark! Beep-beeping bats locate insects and avoid obstacles by bouncing sound waves, imperceptible to humans, off objects as they fly. The female katydid wears her ears on her knees; by waving her front legs she zeroes in on the male’s mating call. Cold-blooded rattlers heat-sense warm-blooded rats and mice. And just as an astronomer opens the aperture on his telescope, so the owl at night widens his enormous eyes for light from far off stars.