National Geographic : 1975 Jul
End of a long journey: With a dusky cygnet between them, a mated pair arrives on Chesapeake Bay. Whistlers are monogamous, and stay with their brood-as many as six youngsters-through the spring migration. After this family returns north, the cygnet will join other immature and nonbreeding swans for at least two more years before mating and starting its own family. swan and the major geographic area where it was banded. The code can pinpoint the indi vidual amid thousands of birds. The percentage of resightings has been re markable because we are able to read the neckband codes at some distance with power ful telescopes. Of a test group of 179 Mary land swans neckbanded as well as metal banded on the lower leg, we recovered or resighted 84 percent. This compares striking ly with the 7 percent recovery rate of swans we marked with only hard-to-read Fish and Wildlife leg bands. Family Bond Seems Strong That historic Alaska pair, Bud and Hope, now rebanded as T001 and T002, have pro vided us with an extraordinary mass of data. With help each summer from Angus Gavin, ecologist for Atlantic Richfield Company, we have now identified them for five consecutive summers in their Alaska nesting place on the fringe of the Prudhoe Bay oil field. And for two out of five winters, they've been spotted with their youngsters in Maryland. The pair's nine crossings of the continent total more than 31,500 miles. Tireless Voyager, The Whistling Swan Our best pair, considering depth of data acquired, has to be A303 and A304, which we banded close to the territory of Bud and Hope. We've checked this pair and their broods for four summers in Alaska, four winters in Maryland, and on spring migration in Ohio, Ontario, and North Dakota. Angus Gavin has reason to be proud that the swans are holding their own in his Prud hoe Bay study area. The swans on the North Slope contend with extremely adverse weath er. Yet productivity is stable, due in part to the oil companies' prohibition of hunting on their extensive holdings. We've discovered many important things about whistling swans, but very much re mains to be learned. Romantic tradition, for instance, ascribes faithfulness to swans. Of the few neckbanded pairs we've followed, all seem to be knit in durable family bonds, and they've raised cygnets year after year. But we have seen some couples temporarily separate during winter or on migration as they inde pendently explore new feeding grounds. In any case, the pairs we have followed still rep resent so small a sample that lifelong fidelity for whistling swans cannot be claimed.