Hot Dry Places - Tracks and Shadows: Field Biology as Art - page 64

derlying microhabitat easily disrupted, and within them big scary arachnids occupy the
same nooks and crannies preferred by reptiles.
Desert night lizards, often common under yucca logs, are no larger than a stout
wooden match, with tiny legs, minuscule gray-green scales, vertical pupils, and goggle-
like spectacles instead of eyelids. I've also caught them beneath trash in barren scrub,
with no Joshua trees in sight, while one was sighted among creosote bush roots; so they
might be ubiquitous across the Mohave, numbering in the gazillions. As do many other
lizards, these gecko look-alikes eat arthropods, but unlike others here, they live in fam-
ilies and give birth to young rather than lay eggs. 1 Desert nightsnakes, found less often,
are the size of a big pencil, with flattened heads, dark-spotted bodies, and pearly bel-
lies; rear-fanged yet easygoing when handled, they subdue lizard prey with a venomous
bite. They are related to frog-eating tropical cat-eyed snakes, and likewise crawl about
at night, hiding under surface objects by day.
Given the zeal with which captive desert nightsnakes consume desert night lizards,
herpetologists long assumed a deadly intimacy between the two reptiles. My students
and I were thus surprised to discover mostly diurnal species in the stomachs of these
little serpents: of ninety-two food items in museum specimens, only four were nocturnal
lizards. This paradox, that “night” snakes mostly eat “day” prey, was resolved during
a conference in Baja California when I skipped lunch to scout nearby arroyos. While
strolling about I lifted a board; wary of scorpions, I discovered instead a nightsnake
swallowing an orange-throated whiptail half its size. Because there were no burrows
under the board from which the predator could have stalked a sheltered lizard, it must
have arrived earlier to ambush a wide-foraging prey. Confirmation of this scenario came
on another afternoon that same spring. An M.V.Z. colleague saw a side-blotched lizard
enter a hole and emerge struggling, whereupon he pulled it free with a nightsnake at-
tached to one leg! Together our observations trumped conventional wisdom, by showing
that these temperate-zone “cat-eyes” are diurnal stationary hunters. 2