Word: roeder
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...pings of an enemy radar. They transmit pings of their own designed to confuse an oncoming fighter or trick an attacking missile into veering toward empty air. Such sophisticated electronic countermeasures may be the latest thing in aerial warfare, say Entomologists Dorothy C. Dunning and Kenneth D. Roeder of Tufts University, but the idea is not at all new to non-human flyers. For millions of years, shifty moths have been using similar sound-pulsing stunts to protect them selves from marauding bats...
Bats hunt night-flying moths by echolocation, uttering rapid chirps of ultra sonic sound and flying toward echoes that bounce back from their prey. It is a simple and effective system, but Dr. Roeder proved several years ago that noctuid moths can hear the search sonar of a cruising bat and take evasive action. To save their lives, they fold their wings and dive to the ground or shift suddenly into a zigzag course (TIME, June...
Having analyzed the moth's sonar-detecting apparatus in the laboratory, Roeder and Treat tried it out in the field against real bats. They set up their apparatus on a Massachusetts hillside, and at nightfall their wired moth began to detect the ultrasonic cries of bats. From the traces on their oscillograph, the biologists could tell whether an invisible bat was approaching or flying away. Later, when Roeder and Treat turned on a powerful floodlight, they could watch the bats diving on their prey and hear, through the captive moth's ear, the bats' searching sonar beeps...
...methods of escape, the two scientists set up a floodlight and trained a camera on its beam. When an insect flew across the floodlit area, the operators opened the camera's shutter and turned on their electronic beeper to simulate a cruising bat. "Many insects." say Roeder and Treat, "showed no change in flight pattern when they encountered the sound. In others, the changes in flight path were dramatic in their abruptness and bewildering in their variety. One of the commonest reactions was a sharp power dive into the grass. Almost as frequently the dive was prefaced or combined...
...order to measure the value of such tactics, Roeder and Treat studied 402 floodlit meetings between moths and bats. They noted which moths made evasive maneuvers and which were caught. "The selective advantage of evasive action," they concluded dryly, "was 40%, meaning that for every 100 reacting moths that survived, there were only 60 surviving non-reactors. This figure is very high when compared with similar estimates of survival value for other biological characteristics. It seems more than adequate to account for the evolution of the moth's ear through natural selection...