Born in Christine, North Dakota, a small village around 20 miles south of Fargo, he was introduced to the study of birds by a distant cousin who was a game warden.

After high school and junior college at Wahpeton, he enrolled at North Dakota State University to major in zoology.

He then moved to Washington State University for his master's degree, encouraged by a professor who suggested that he could have a career in ornithology.

This was published in The Condor and the article attracted the attention of Charles Sibley who invited him to consider a Ph.D. at Cornell University with him, with his work focusing on the phylogeny of six ducks.

After completing his graduate degree, Johnsgard moved to England at the Wildfowl Trust at Gloucestershire founded by Sir Peter Scott.