William Alanson Bryan, Jr. was born near New Sharon, Iowa on December 23, 1875, the son of William A. and Catherine Pearson Bryan. He earned his BS from Iowa State College in 1896 and although he never earned a PhD, was generally addressed as Dr. Bryan. From 1895 to 1897 he served as special lecturer in museum methods at a number of midwestern universities and during 1898-99, he was assistant curator in the Department of Ornithology, Field Columbia Museum in Chicago. In 1899 he came to Hawaii as a special representative for the U.S. Department of Agriculture to investigate the gauno of the Islands. After this work completed, he travelled for a year in Europe and the U.S., studying museum administration. In 1900 he returned to Hawaii as Curator of Ornithology at the Bernice P. Bishop Museum in Honolulu. He resigned this post in 1907 to devote his time and energy to organizing and serving as the first president of the Pacific Scientific Institution whose purpose was to make a scientific survey of the Pacific.

In 1909 Bryan married Elizabeth Letson of New York, an eminent scholar-scientist in her own right. Elizabeth Letson was born April 9, 1874, daughter of Augustus and Nellie Webb Letson. She was educated at the Philadelphia Academy of Natural Science and the U.S. National Museum in Washington, D.C. For seventeen years, from 1892 to 1909, she served with distinction in the Buffalo (New York) Society of Natural Sciences, and was the first woman in the country to be elected director of a museum of natural science.

Upon their marriage, the Bryans moved to Hawaii and built a home on Punahou Street, Honolulu. He served as professor of zoology and geology at the College of Hawaii (1909-1919); and she, as the College's librarian (1912-1917). Elizabeth L. Bryan was an authority on conchology and until her death in Hawaii in 1919 maintained an active interst in the field; it is her collection which illustrates her husbands most important published work, Natural History of Hawaii, first published in 1915. A revised second editon, to be issued in 1936, was never published.

During his years in Hawaii, Bryan was active in politics and civic affairs. He was a member of the Democratic party, some of whose records he retained, and in 1913 was quite confident of being appointed governor of Hawaii to succeeed Walter Frear; President Wilson appointed Lucius Pinkham instead. He was again dissappointed in 1918 when he was passed over in favor of Charles McCarthy. His interests also included the Socialist Party of Hawaii; and the designation of Hawaii as a Free Treaty Port rather than a state.

In his activities in many fields he was a promoter and a showman. Many of his lectures were illustrated with his own photographs. In addition to his Natural History of Hawaii, Bryan published numerous scientific papers on ornithology and zoology.

Political disappointment, coupled with the death of his wife in 1919, led Bryan to relocate to southern California where he became director of the Los Angeles County Museum (1921-1940). He married Maude H. Robinson in 1921, and died in Los Angeles in 1942 at the age of 67.