Courtship not performed in ternery. Copulation on land or water, often exchange fish, duration 3 sec. Male and female attain sexual maturity at 2 yrs. Maximum breeding age unknown. Least tern is a migrant, present in Ill.
Sandbars are preferred nesting habitat.
Severe floods may delay or prevent nesting. For Bell I., Il. Sex ratio unknown. BENT, A.C. 1921.