Of the North American species, great horned owls are one of the first to nest in the spring.

Great horned owl eggs have been taken as early as late November and early December in Florida. In Texas, they lay in January and early February. As one moves northward, a direct correlation between latitude and date of laying can be observed, until the extreme is reached in Labrador where sets are often not completed until after the first of April. In the western part of the country the correlation with latitude is often obscured by the effect of altitude upon climatic conditions.

Sources: (Baumgartner, 1983; Bent, 1937; Forbush, 1929)
Image: Kenneth Bader