Science News - October 22, 2011

Lumpy lunar illusion Are you folks aware of a phenomenon based on the universal expectation that objects are illuminated by light coming from above? Several startling optical illusions are based on this quirk of the mind. For example, the sharp moon map in “Orbiter delivers sharp moon map” (SN: 7/30/11, p. 12) makes the moon look like it is covered with big bumps! Turn the page upside down, and voila — the bumps turn into craters. Jeff Brewer, Newton, Mass.

a second cat who was at best a spider hunter. He was mostly unnoticed by the jays. Incidentally, we did not find him being followed by spiders. Larry Sage, Truckee, Calif.

P. S. My father managed to kill only one crow in his 50-plus years on the property. The crows came and went with impunity.

Ann Harmer, Costa Mesa, Calif.

Count on crows to know
Regarding “When birds go to town” (SN:
8/27/11, p. 26), I have observed other
corvids that recognize a specific animal
that has proven to be a threat. We had
a cat that successfully caught a Steller’s
jay chick. For the remaining five years
of the cat’s life, she was a marked assas-
sin! She could not leave the house with-
out invoking a posse of jays constantly
squawking and following her. We had
My father, whose vendetta against crows
was legendary, always kept a shotgun
by the back door. As hundreds of crows
gathered each evening across the pond,
he would grab the gun and “stealth-
ily” sneak around the house, hoping to
blast a few of “the dratted critters.” It
was a joke among us kids, because the
instant he peeked around the house,
all the crows — with more racket than
you can imagine — took off immedi-
ately. We began to experiment, sending
my mom out with a broom using the
same “sneaky” behavior exhibited by
my father. The crows figured out the
ruse immediately, sitting calmly on the
ground or in the trees, drinking from
the pond and generally thumbing their
beaks at us.

In recent years I have interacted with the University of Washington’s resident crow population as a two-legged peanut dispenser to enliven multiple quarter-mile strolls each day between my office and my car. “Old Gimpy” now approaches me within an arm’s reach when I place a few morsels atop my red Subaru. Fred Utter, Seattle, Wash.

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