Corncrakes breed on their first year. Once the males have reached their breeding grounds and selected a patch of suitable habitat, they start to sing to attract mates.
Corncrake do not hold a specific territory as such, though the singing males do space themselves out.
Once the male has attracted a female and mated, he will move some distance away and continue to sing to attract another mate. The female will incubate and rear the young by herself.
The nest is built on the ground in concealing vegetation, close to the singing post of the male. It is a shallow cup lined with dead leaves of nearby vegetation. Stems are often pulled over to form a loose canopy.
A clutch of 8-12 grey-green blotchy eggs are laid one a day from early May onwards. If the eggs are lost, she will lay a replacement clutch. Incubation begins with the last egg and lasts 16-19 days. The brood hatches synchronously.
When the young are only a couple of days old, they leave the nest and start to follow their mother. The female feeds the chicks until they are independent. Parent-young bond is initially strong, but often of short duration. Many broods become independent of their mother early, at 10-15 days, due to second nesting attempts. After this the chicks live independently, though the young are fully fledged only at 34-38 days after hatching. The young from second clutches remain with their mother for a few days longer than first brood chicks.