Animal life histories and environments
Shelford studied tiger beetles, aquatic animals and marine communities. His interests included life histories, reproduction, light and climate, together with apparatus for simulating environmental conditions.
His animal ecology examined organisms within connected environments rather than treating individual form alone. Field investigation and experiments under controlled conditions complemented one another.
Ranges of environmental tolerance
The law of tolerance associated with Shelford holds that successful survival and reproduction depend on suitable ranges of environmental conditions. Too little or too much of factors such as temperature, light or moisture can impose limits.
This redirects a question about which animals occur at a site towards the conditions allowing them to persist. Particular limits require investigation for the organism, life stage and environment concerned.
References: [1]
A society and a community science
Shelford became the first president of the Ecological Society of America when it was founded in 1915. His books included Animal Communities in Temperate America (1913) and Bio-Ecology (1939), coauthored with Frederic Clements.
These works sought to bring animals and plants within a shared study of communities. He worked at the University of Illinois from 1914 until retiring in 1946, combining teaching with field and experimental research.
References: [1]
Debating the role of scientific societies
Shelford argued that ecologists should help preserve natural areas. A 1945 ESA restriction on direct efforts to influence legislation reflected disagreement over the balance between scientific work and public action.
He helped organize the Ecologists’ Union in 1946. After reorganization, it incorporated as The Nature Conservancy in 1951, developing an organizational route for conservation distinct from a scholarly society.