National Geographic : 1954 Aug
A New Bird Immigrant Arrives 281 First in History to Settle in Mainland North America Without Known Human Aid, the Cattle Egret of the Old World Suddenly Appears in Several States BY ROGER TORY PETERSON T cHE United States has a new bird citizen. Strangely enough, it appears to have come from the Old World by way of South America by the power of its wings and the wind alone. The newcomer is the cattle egret, a beautiful member of the heron family. For centuries the cattle egret (Bubulcus ibis) has been a familiar sight in southern Spain, in Africa, and in the warmer parts of Asia. Dancing attendance on grazing herds, it catches grasshoppers and other insects stirred up by cattle, water buffalo, and such wild animals as the elephant and hippopota mus; sometimes it picks parasites from their hides. Often travelers see these alabaster birds standing ornamentlike on the broad backs of pachyderms (page 287). Found First in British Guiana In the New World the cattle egret was unknown until 20-odd years ago, when it appeared suddenly in South America. Just how it made the transatlantic jump, and exactly when, no one knows. All we are sure of is that cattle egrets appeared about 1930 in British Guiana, there to find herds of Brah man cattle and native herdsmen just as in India, where the species is abundant. The birds prospered, and within two decades the flocks had increased and spread to Suri nam, Venezuela, and Colombia. Oddly enough, their nesting places in South America have not yet been located. How did they come? Could they be de scendants of birds that had escaped from some zoo, perhaps the one at Georgetown, British Guiana? We ornithologists have no evidence to prove such a hypothesis. Did someone de liberately introduce them from abroad? Not likely, for surely there would be some record of such a project. Did the first European or African cattle egrets reach South America as stowaways, perhaps on a cattle boat? Even this is un likely, for a number of avian hitchhikers would have had to make the journey to provide a nucleus for successful breeding. The most plausible theory, it seems, is that the birds were wind-borne. The At lantic is only 1,770 miles wide between the bulge of Africa and northern South America, and the birds are good flyers. Assisted by strong winds from the east, they could con ceivably have covered the distance before they were completely exhausted. Early in 1937, we know, a flock of fieldfares (north European counterparts of the American robin) were caught in a wind while trying to cross from the mainland of Europe to Eng land for the winter. They landed in southwest Greenland, pocketed in a corner where birch trees around fjords made existence possible. They are still nesting there, and the Eskimos have given them a name almost as long as the birds-orpingmiutarssuaq. If the cattle egret likewise came to the New World on its own two wings and the wind, it is the only Old World bird in history to establish residence on the mainland of the Americas without human aid. All the other foreign birds which have taken up residence here within historical times were introduced by man. Bird Sought Abroad Turns Up at Home So far as was known, however, the cattle egret had not reached North America when I went to Spain in 1952 to work with Guy Mountfort, secretary of the British Ornitholo gists' Union, on data for our Field Guide to the Birds of Britain and Europe (page 285). One bird which I particularly wanted to see and study in Spain was the cattle egret. Little did I know that in my absence the bird I had gone 3,000 miles to observe would suddenly appear in my own country, the United States. The story begins in Massachusetts. Wil liam H. Drury, Jr., of Cambridge, had been in the Guianas several years before, but cattle The Author Roger Tory Peterson, one of the outstanding orni thologists of our time, is the author and illustrator of notable works on the birds of North America and Europe. For two decades he has been associated with the National Audubon Society as staff member, editor, and lecturer. In 1950 Dr. Peterson was awarded the John Burroughs Medal for exemplary nature writing.