The Migration of North American Birds (1935) — Themes and Context

Elliptical Routes and the Golden Plover

One of the most striking patterns Lincoln details is the elliptical migration of the adult golden plover. Unlike the general rule that spring and fall routes coincide, these birds trace an enormous oval: southward over the Atlantic Ocean to South America, then northward through the Mississippi Valley. Lincoln specifies the axes—2,000 miles minor, 8,000 miles major—and notes that only fully adult birds use this path; most immatures take a different, interior route. This observation is typical of Lincoln's method: he distinguishes age classes, quantifies distances, and flags exceptions without romanticizing them. The plover's journey is presented as a matter of record, not wonder.

Food as a Constraint on Flyways

Lincoln's analysis of the Atlantic coast route reveals a pragmatic ecological reasoning. He notes that while a chain of islands from the Bahamas to the Lesser Antilles seems a natural highway, only about 25 species travel beyond Cuba, and just 6 reach South America via the Lesser Antilles. The reason, he argues, is food scarcity: the total land area east of Puerto Rico is smaller than Rhode Island, and even tropical habitats could not support large numbers of birds. This attention to resource limitation—rather than mere geography—shows Lincoln's approach as a biologist concerned with carrying capacity, not just mapping.

Segregation by Age and Experience

Throughout the circular, Lincoln emphasizes that migration is not uniform within a species. The golden plover example is one instance; another is the brant, whose round trip forms a 3,000-by-1,000-mile ellipse. More broadly, Lincoln discusses "segregation during migration," noting that young birds often travel separately from adults. This pattern emerges from banding studies, a method Lincoln champions. He avoids sweeping statements about instinct, instead focusing on observable differences in timing and route. The result is a portrait of migration as a learned, variable behavior, shaped by age and experience.

Lincoln's circular rewards readers who attend to its details: the precise mileages, the species counts, the careful distinctions between age classes. It is not a book to skim for general impressions but one to consult for specific data points. Readers interested in how early twentieth-century ornithologists thought about movement and ecology will find a wealth of concrete observations, each tied to a particular species or route. The work stands as a record of what was known—and what remained mysterious—in 1935.

Lincoln’s golden plover, traced in its huge ellipse, made me think of my grandfather’s field notes—pencil sketches of shorebirds he never saw again. That feeling of a map growing emptier returned when I found History of Birds — Text and Context; both books read like quieter elegies for what our watching once meant.