National Geographic : 1967 Sep
Sharing the Lives of Wild Golden Eagles that could be reached only by using climbing spurs; they conquered sheer 400-foot cliffs. Often hungry themselves, the youths tight ened their belts and kept score of the kinds and quantity of food in the eagles' diet. Once they considered pilfering a fresh grouse from the eaglets for their own supper. The boys endured discomfort, disappoint ment, and discouragement. But when an eagle parent swooped in with food and the light was right, unforgettable moments of discovery rewarded them. For two summers Charlie and Derek camped in eagle country, hiking or driving over bone-jarring wilds to reach remote nests. Occasionally I visited the boys to offer advice on photography, camp neatness, and the nutritional value of cooking a few good meals. I checked them out, as I had Jerry, on the use of ropes and dangers of cliff climbing. Once, when their meat supply had spoiled, I treated them to five pounds of steak. Frank and I were proud fathers, during the boys' second summer with the eagles, when our sons handed us a letter from Bates Little hales of the NATIONAL GEOGRAPHIC'S photo graphic staff: "Dear Charles and Derek: "I received rolls 61 through 71 of your last shipment. You now have a magnificent series on the golden eagle. It far surpasses our high est expectations. There are some great dra matic portraits beautifully handled, and the flight shots are fine." Bully's Role Played by Big Sister Daily notes taken by the boys at their six blinds give an interesting account of eagle behavior. Charles recorded the aggressive conduct of a female fledgling in the nest. "The female is always first to claim the food. She generally bullies her smaller broth er. This morning the adult male eagle brought a jack rabbit and dropped it off as he flew by. The young female immediately grabbed it and covered it with her wings. "The male fledgling squawked at the edge of the nest, but did not attempt to claim the food. After a few moments the adult female arrived and looked the situation over. She knocked over the young female with a stroke of her wing, tore up the rabbit, and divided it equally between both young." Another day, Derek wrote: "This morning we spotted the mother returning with food. She flew upwind to within a few yards of the nest, then rolled over on her side, exposing her prey. The hungry young female, who had already made her first flight, watched intently, and as the adult turned away she flew from the cliff, maneuvered alongside her mother, and attempted to snatch the food. The adult, being annoyed, made a strong downstroke of her wing that sent the young eagle head over tail and forced her to crash-land on the slope below. Later in the day the mother twice repeated her performance of flying close by the nest with food, apparently to entice the young male that had not yet flown." Jerry, meanwhile, continued to amass figures that we hoped would tell a more general story. He learned that 45 pairs of golden eagles laid an average of two eggs per nest over a two-year period, and hatched an average of 1.8 eaglets. Eighty-seven percent of those that hatched survived to leave the nest. However, when six unsuccessful pairs were included, the average of fledged eagles dropped to 1.4 per nest. These studies, comparing the young re searcher's Montana figures with productivity records from other parts of the country, showed that Montana eagles were producing enough young to maintain their present num bers. Jerry compiled statistics on mortality of eaglets in the nest and, by recording the fate of banded eagles, on causes of death after the eagles left the home aerie. He found proof that fledglings took fatal tumbles from their nests. He also noted that men, for one motive or another, destroyed nests and young. Banded eaglets, off on their own, sometimes were shot or poisoned, or were struck by cars while eating carrion on the highways. Hunters and other people often returned the victims' numbered bands. Interpreting these records, Jerry learned that at least half the eagle deaths in his area were caused by man and his lethal agencies. But the study raised a nagging question: Does man have a case against the eagle? To learn the makeup of the golden eagle's diet, Jerry painstakingly identified remains of Perilously cantilevered 400 feet above a valley floor near Brackett Creek, Montana, an eagle's nest supports researchers Reyn olds, right, and Jack Seidensticker. During a six-week period the students often made this risky climb to measure the young birds' growth with a spring scale. KODACHROME BYCHARLESAND DEREKCRAIGHEAD© N.G.S.