If no suitable old nests can be found, then the merlin will build a loose nest of sticks in a tree cavity, on a roof, on a cliff ledge, or occasionally on the ground. The nests are found in both coniferous and decisuous trees, often near water. Unlike other falcons, they have been known to incorporate greenery into the nest. Mate fidelity has been obwserved, but the pair does not remain together during the winter. It is thought that the pair will use the same general area for nesting each year but don't necessarily use the same exact nest.
Courtship is full of aerial displays, vocalizations, and food begging by the female.
Following successful copulation, the female will lay eggs at 2-day intervals. Partial incubation occurs following the laying of the first egg, but full incubation will not begin until all of the 4-5 eggs have been laid. This delay of full incubation means that the eggs will hatch at nearly the same time. The partial incubation serves to keep the first-laid eggs viable without facilitating development of the embryos inside. Nesting duties seem to be divided between the sexes, with the male doing al of the hunting and the female doing most of the incubation.