Web edition: October 7, 2011
Print edition: October 22, 2011; Vol.180 #9 (p. 31)
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.
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 assassin! She could not leave the house without invoking a posse of jays constantly squawking and following her. We had 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.
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 “stealthily” 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 immediately. 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.
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.
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.