National Geographic : 1945 Apr
Photoflashing Western Owls BY LEWIS W. WALKER With Illustrations from Photographs by the Author WLS were far from my mind when in early spring I chose to renew my ac quaintance with a colony of great blue herons.* These graceful long-legged, long necked birds had become personalities in past seasons when I spent months making a photo graphic record of their nesting habits, 87 feet above the ground. Their favorite perches were still occupied, but now the nests, 40 or more, which formerly were filled with raucous voiced young, seemed uninviting to them. The herons were craning their necks from side to side as if to get a better view of some thing not visible from the ground. An ascent to my old photographic blind was illuminating. A great horned owl had usurped one of the nests, and reposing in it were two young, about half grown. Even though great horned owls are unprotected here in California, I did not have the heart to destroy this intruding nocturnal family. Diligent search disclosed another nest of horned owls, in which were two young of approximately the same age as those in the heron rookery (page 483). An ascent was made to the owl's nest in the heron colony, and the two young were removed to the other site, in the hope that they would be adopted by their foster parents. However, at every ascent of the 62-foot tree to place a young one in the nest, the other would walk off the edge and flap to the ground. Moving a Bird's Nest I tired of climbing long before the owls wearied of sudden descents and slow lifts. A companion, from a comfortable position on the ground, kept me posted on the whereabouts of the young, but his facetious remark, "They think it's a new game," did not help. In desperation I conceived another plan. This was an experiment to determine the abil ity of the adults to follow the calls of their young and their willingness to break off former nesting ties. One more ascent was made. Again the young exploded from the nest. After the nest was bound with cord, it was lifted from the crotch and lowered. Forty feet away and only ten feet above the ground the nest was placed in a crotch of a tree. Then the four beak-snapping young were introduced to their new home. Dubious of the ultimate success of this transplantation, I returned to San Diego. Dusk, and curiosity, drew me back. From the old nesting site came a single mourn ful whoo, which was answered by a sound like escaping steam from the transposed nest. Al most immediately an adult dropped from the treetops, left a rodent carcass with the young, and disappeared into the darkness. With success well on the way, the possibility of night flashlights came to mind. A few days after the young were trans planted, a platform was constructed against an adjacent tree, upon which was nailed a large cardboard packing box. This was my home for the first half of almost every night for the next three weeks. Camera openings and observation holes were cut. Silvered flash-bulb reflectors were placed at measured distances to give the correct light intensity. Wires led from an automobile stor age battery on the ground. Because the large reflectors had to remain unobstructed, camou flage was impracticable (page 484). A Noiseless Flight That first evening, twilight deepened into night without a sign of the adults. Mosqui toes buzzed incessantly and came through the lens openings. Nine o'clock passed. Then one of the young started an intermittent rasping call, repeating it every 10 or 15 seconds. When he tired, it was taken up by another, with hardly a break in regularity. It was obviously a call of hunger. After 30 minutes there came a sharp clump on top of my cardboard blind. For several minutes vi brations and talon scratches indicated the ap proximate position of the adult, evidently siz ing up the observation platform, so alien in the forest of eucalyptus trees. A sudden vibration, followed by a gust of wind, told of departure. There was no swish or rustle of wings, though the take-off was less than two feet from my ears. This amaz ing power of noiseless flight, like a moving shadow, never ceased to be a wonder. On leaving the blind, the owl evidently flew to a near-by tree and there voiced a ques tioning whoo. Immediately came a three syllable answer, and I believe the pair of adults landed on the same branch to discuss the situation. Soon a hollow whining cry came * See "The Large Wading Birds" (Herons, Ibises, and Flamingos), by T. Gilbert Pearson, NATIONAL GEOGRAPHIC MAGAZINE, October, 1932.