Beginning in 1916, Field was in the employ of the U.S. Bureau of the Biological survey, and later in his career was the United States representative to the League of Nations International Commission on Water Pollution Control.

[3] He did postdoctoral studies in Naples, Italy at the Stazione Zoologica, and at Ludwig Maximilian University of Munich.

In 1905, conducted a study on the effects of coal tar on oyster beds,[13] and he served as a scientific consultant to the Rhode Island Commissioners of Shellfisheries in a pioneering 1910 water pollution case brought by Rhode Island oyster farmers against the Providence Gas Company.

[14] Prof. Field became a director of the Massachusetts Audubon Society,[4] and in 1911, he was elected president of the National Association of Shellfisheries Commissioners.

[15] Following his work in Massachusetts in 1916, Field joined the Bureau of Biological Survey of the U.S. Department of Agriculture in the capacity of supervisor of the 74 national bird and mammal reservations in the United States.