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Q: What's the "Acoustic Arms Race" going on in your backyard this summer?

A: It's the "bats and moths in sonar combat," says biologist William E. Conner in "American Scientist" magazine. Animals can hunt either passively by listening for noises made by their prey, or actively (as most bats and some whales do) by projecting sounds and then listening for telltale echoes, called "echolocation." In essence, they "see" using sound.

Radar ("radio detection and ranging") uses pulses of radio waves for the "send" signal; sound waves project better underwater, hence the development of sonar ("sound navigation and ranging"). "Other than the difference in signal used, it operates on similar principles to radar." Functional radar systems were driven by the approach of World War II. Human-designed sonar predates radar by some 30 years, spurred on by World War I submarines and by the sinking of the "Titanic," since sonar could be used to detect icebergs in darkness and fog.

Biological echolocation evolved more than 65 million years ago in bats, making them masterful hunters that use short-wave sonar to detect prey as tiny as mosquitoes, beetles and moths. But the moths have learned to produce their own sounds to confound the bats' signals. "The ploy and counterploy of bats and moths comprise a diffuse arms race... we are just beginning to understand," adds Conner. Some jamming moths produce their signal only when the bat has "locked on" to them and the danger is great.

A myriad number of insects ply the nighttime skies, including 11,000 species of tiger moths and an estimated 200,000 other kinds of moths, not to mention beetles, katydids, crickets, flies and much more. "Any insect that flies after dark must have a strategy for dealing with nature's ultimate nocturnal predators--echolocating bats. The race is on."

Send questions to StrangeTrue@compuserve.com.

Local events heading

  Today is Monday, April 21, the 111th day of 2014. There are 254 days left in the year.

1864 -- 150 years ago: The female sex seems to have gone crazy on the subject of dry goods. When high prices keep them from increasing their wardrobes, they turn to stealing. Yard goods, hats, shoes and other items are being picked up and carried home.
1889 -- 125 years ago: Members of Everts Commandery No. 18, Knights Templar, under Commander H.C. Cleaveland, marched from the Masonic Temple to Trinity Episcopal Church for their annual Easter services.
1914 -- 100 years ago: Nate Hultgren pitched the Augustana College baseball team to a 10-3 victory over Carthage, striking out 11 men and allowing only four hits.
1939 -- 75 years ago: Marvel Leonhardi, a Rock Island High School senior, was the winner of an essay contest on advertising sponsored by The Argus and Advertising Age, a national advertising publication.
1964 -- 50 years ago: The Augustana College band drew a crowd of 1,200 people for its annual home concert in Centennial Hall. The size of the crowd was indicative of the fact the band is rapidly approaching the stature of the Augustana Choir.
1989 -- 25 years ago: A benefit to raise money for extracurricular activities in the Rock Island Milan School District will be April 27 at the Quad City Downs harness race track. People buying $17.50 tickets to the second annual "Night at the Quad City Downs" will be entitled to an evening of harness racing and dinner.

(More History)