He taught
biology for a short period of time at
Marshalltown High School in
Marshalltown, Iowa. After that, he joined the Bureau of Biological Survey. He became a director of the
U.S. Fish and Wildlife Service before which he served as chief of the old Bureau of Biological Survey at the
U.S. Department of Agriculture. In 1940, when Biological Survey and the Bureau of Fisheries united into the Fish and Wildlife Service, he became a director, and stayed as such until 1946. During that time, he served as a deputy coordinator of fisheries and a U.S. delegate to the
International Whaling Conference and had responsibility for adding millions of acres to the
National Wildlife Refuge System. In 1946, he retired from the
federal government and became the president of the Wildlife Management Institute. He served there until 1970, after which he became the chairman of the board. From 1959 to 1976, he was a chairman of
NOVA Parks. He was called upon by the governor to the Virginia Outdoor Study Commission, in 1966, during which year he drafted a plan on how to conserve and develop the state's natural resources. In 1975, he and his colleagues were chosen by the American Forestry Association as one of the selected groups for the National Hall of Conservation. He wrote four books and coauthored six others, all of which were on birds and conservation. He joined bird expeditions to the
Andes, the
Amazon,
Europe, the
Mediterranean,
South Pole, and
Alaska. ==Organizational affiliations and awards==