Focus on Nature

FOCUS NATURE THE DESERT'S WHITE-THROATED WOOD RAT

Desert rats are cute. A contradiction? In stories it's always mice that are cute: Stuart Little, the country mouse. Never rats. Rats, like the coyote and other mammalia non gratae, are always depicted as hustlers, tricksters never cute. Even naturalist Joseph Wood Krutch (See Arizona Highways, June '91), who surely knew a rat by any other name was still a rat, titled an essay about the kangaroo rat, "The Mouse that Never Drinks."

The white-throated wood rat, more commonly called pack rat or trade rat for its habit of collecting things to lug off to its burrow, is one of the cute ones. Eyeglasses, buttons, twigs, cow dung, bits of glass, mesquite beans, thread, cholla buds one field biologist even found an automobile hubcap among a pack rat's collection of odds and ends.

Various subspecies of pack rat live from sea level to 12,000 feet, coast to coast, and from Canada to Central America. The one most common throughout Arizona, except north and west of the Colorado River, is the white-throated wood rat.

Paleobiologists have turned up valuable information in pack-rat middens. The rat not only collects plant parts, you see, it makes nice little piles and then urinates on them. This urine is a good preservative; highly concentrated, it cements the debris into small chunks. By taking the chunks apart and dating the materials, a researcher at the Arizona-Sonora Desert Museum learned that 4,000 years ago the Sonoran Desert was a much wetter place, perhaps by as much as two or three inches of annual rainfall, and an oak-piñon-juniper woodland covered what is now desert.

You can identify a pack-rat den beneath a pile of rocks or at the base of a large cactus plant by piles of chollacactus joints surrounding the entrance. Spiny cholla joints, and sometimes prickly-pear pads, provide protection from predators and food for pack rats, which somehow manage to run across the sharp spines without becoming impaled.

The trouble with pack rats is kissing bugs. Fellow travelers, they reside in pack-rat dens where they're usually content to chomp on their hosts. But if you live in the desert, chances are you've been bitten by a kissing bug and don't know it. Maybe a little redness, a slight itch. I'm not so lucky. On me, their bites raise screaming red welts the size of silver dollars. Worse yet are people allergic to kissing bugs who go into dangerous anaphylactic shock when bitten.

When I discovered some pack rats nesting in a corner of my carport shed, I tried trap-ping them alive. A miserable failure. Remove one and the following morning I'd find another cute little bat-eared critter in my trap. I cleaned the shed, sweeping away the nest of upholstery stuffing pilfered from a stored easy chair. The next day, a large cholla joint, bristling with spines, lay at the door of my shed. A warning.

I gave up. Now, during kissing-bug breeding season, when the bloodthirsty assassins move around looking for partners, I douse myself with heavy-duty insect repellent before going to bed.