Diet manipulating its prey, a lizard, before swallowing|alt=A white heron with grey legs and a yellow/orange bill standing in green grasses throwing a lizard with its bill Herons, egrets, and bitterns are
carnivorous. The members of this family are mostly associated with
wetlands and water and feed on a variety of live
aquatic prey. Their diet includes a wide variety of aquatic animals, including fish, reptiles,
amphibians,
crustaceans,
molluscs, and aquatic insects. Individual species may be generalists or specialize in certain prey types, such as the
yellow-crowned night heron, which specializes in crustaceans, particularly
crabs. Many species also opportunistically take larger prey, including birds and bird eggs, rodents, and more rarely
carrion. Even more rarely, herons eating acorns, peas, and grains have been reported, but most vegetable matter consumed is accidental. The wings may be used to frighten prey (or possibly attract it to shade) or to reduce glare; the most extreme example of this is exhibited by the
black heron, which forms a full canopy with its wings over its body. Some species of heron, such as the
little egret and grey heron, have been documented using bait to lure prey to within striking distance. Herons may use items already in place, or actively add items to the water to attract fish such as the
banded killifish. Items used may be man-made, such as bread; alternatively,
striated herons in the
Amazon have been watched repeatedly dropping seeds, insects, flowers, and leaves into the water to catch fish. Three species, the
black-headed heron,
whistling heron, and especially the two
cattle egret species, are less tied to watery environments and may feed far away from water. Cattle egrets improve their foraging success by following large grazing animals, and catching insects flushed by their movement. One study found that the success rate of prey capture increased 3.6 times over solitary foraging.
Breeding , are solitary breeders. To advertise for mates, males use loud, characteristic calls, referred to as booming.|alt=A brown heron with brown, back, and beige coloured streaks stands in similarly coloured dead grasses, its head pointed upwards While the family exhibits a range of breeding strategies, overall, the herons are
monogamous and mostly
colonial. Most day herons and night herons are colonial, or partly colonial depending on circumstances, whereas the bitterns and tiger herons are mostly solitary nesters. Colonies may contain several species, as well as other species of waterbirds. In a study of little egrets and cattle egrets in India, the majority of the colonies surveyed contained both species. Nesting is seasonal in temperate species; in tropical species, it may be seasonal (often coinciding with the rainy season) or year-round. Even in year-round breeders, nesting intensity varies throughout the year. Tropical herons typically have only one breeding season per year, unlike some other tropical birds which may raise up to three broods a year. In colonial species, displays involve visual cues, which can include adopting postures or ritual displays, whereas in solitary species, auditory cues, such as the deep booming of the bitterns, are important. The exception to this is the boat-billed heron, which pairs up away from the nesting site. Having paired, they continue to build the nest in almost all species, although in the
little bittern and
least bittern, only the male works on the nest. Generally, herons lay between
three and seven eggs. Larger clutches are reported in the smaller bitterns and more rarely some of the larger day herons, and single-egg clutches are reported for some of the tiger herons. Clutch size varies by latitude within species, with individuals in temperate climates laying more eggs than tropical ones. On the whole, the eggs are glossy blue or white, with the exception being the large bitterns, which lay olive-brown eggs. ==Taxonomy and systematics==