Herons nest in colonies, or heronries, usually in the tops of tall trees near water, but in the north of Britain they often choose cliffs, reed-beds or bushes. Nesting begins early in the year and the male defends his own tree-top territory during the breeding season. He threatens any approaching male by straightening his neck, fluffing out the plumes on his head, throat and back and snapping his beak. If the intruder doesn't retreat immediately, he may then lunge at him viciously.
The male calls frequently, day and night, trying to attract a mate. When a female appears, he displays by stretching his beak towards the sky and when she comes closer, he lowers his head over his back and claps his bill repeatedly.
The female usually builds the nest, using sticks and twigs; it is a large structure with a shallow, saucer-shaped hollow in the top. The same nest is used year after year and so it grows in size until it is several feet across. Fresh grass and bracken is added to serve as a lining for the 4 or 5 pale blue eggs. Most eggs are laid at the end of March. Both parents share incubation which starts as soon as the first egg is laid. The newly-hatched chicks are covered in long, blackish-brown down which is bristly on the top of the head and this gives them a comical crest! They are noisy youngsters, keeping up a constant 'agagagagag' call as they beg regurgitated food from both their parents. The eggs hatch at different times, so in years when there is a shortage of food, the biggest chicks survive and the smaller ones starve. In plentiful years the whole brood will be successfully reared.
The adult herons may fly up to 30km from their heronry to visit good hunting areas.Read More: Herons and Humans