Nesting and breeding habits
Merlins are sexually mature at one year, which is when most females first breed. Many males do not breed until their second year.
Where merlins nest
Territories are traditional, and are used repeatedly from year to year by successive generations of birds, though the exact location of the nest does vary.
A majority of merlins in the UK nest on the ground with nest concealed in heather. Ground nesting is unique to the UK population - their continental counterparts rarely do so.
Since the late 1970s, merlins have started to nest in trees on edges of conifer plantations, feeding on neighbouring open ground. This change in nest site choice mirrors their continental counterparts, and may assist the merlin to extend its range to new areas. Where tree nesting has developed, there has been a reduction in the use of traditional ground nest sites.
Building the nest
The nest, built by the female, is a shallow scrape on the ground, lined with small twigs, pieces of heather, bracken and other material. The 3-5 light buff eggs spotted with red-brown are laid between May and early June at two day intervals. Incubation is by both sexes, but the majority by the female, for 28-32 days, beginning normally with the last egg. Chicks normally hatch close together.
The female stays close to the nest, and is responsible for most of the nest defence, and nearly all parental care. The male provides all food from before egg-laying until after the young fledge. On some occasions, the female will start to hunt for prey when the young are 10 days old.
Young in a ground nest will often leave the nest at 18-20 days and scatter into the surrounding undergrowth. They fledge at 25-32 days, and are independent about a month later.
One brood a year is raised. Replacement clutches are laid after early egg loss.