National Geographic : 1962 Apr
Bathed in infrared light, which appears green through an electronic view finder, a barn owl listens for the sound of a mouse he will catch in total darkness. Unlike bats, which emit high-frequency sound pulses that rebound from the target (NATIONAL GEOGRAPHIC, April, 1961), the barn owl in the light-proof laboratory relies solely on sounds made by his prey. To film the owl's strike, researcher Roger Payne sets up camera and tri pod in a dark flight shed. War-surplus sniperscope, which makes infrared rays produce a green image, guides him in aiming a movie camera loaded with infrared film. Dr. Payne uses strobelights that fire a 70-watt-second flash every 24th of a second. Filters absorb all visible rays. HS EKTACHROME BY NATIONAL GEOGRAPHIC PHOTOGRAPHER ROBERT B. GOODMAN N.G.S. Owl detects the rustle of a mouse and homes in, flying blind. Infrared light does not disturb him. Arrow indicates mouse. Solving a problem of parallax created by the fact that the feet are so far from the ears, the bird computes the mouse's position, brings claws up under the ears, and swiftly pounces. In the last split second, talons snap forward to take the place of the ears in the strike path. Just before impact, the owl extends his eight claws in a pattern six inches long and three inches wide to cover the target area. Left foot grabs the mouse; right foot absorbs the jolt of landing. In darkness, the owl rarely misses on flights up to 24 feet. Body slumps in carry-through. Eyes, shut at impact, reopen.