Herons and egrets are both members of the heron family, Ardeidae – meaning that technically speaking, egrets are essentially herons. Ardea, the genus that comprises the great herons, is reported not to be especially close in an evolutionary sense to Egretta, the genus that consists of smaller herons and egrets. The family Ardeidae is within the order Pelecaniformes.
To make matters of classification even more confusing, some members of Egretta are referred to as herons – for example, the black heron, Egretta ardesiaca. For the purposes of this article, ‘heron’ will be used to describe members of Ardea, and ‘egret’ for members of Egretta.
Distribution, Habitat, and Diet
Herons and egrets are very similar in their ecology. They can inhabit both freshwater and coastal areas, including shorelines, mudflats, marshes, lakes, ponds, and rivers. Both genera are found on all continents except for Antarctica and are widespread on each continent, found in most areas except for those with extremes of temperature.
Members of Ardea have a particular preference for foraging in open areas, and do not appear to be reliant on cover – they are often very exposed during feeding. In contrast, members of Egretta may be more likely to forage along the margins of wetlands, although they still prefer open areas with no canopy.
The primary food source of Ardea and Egretta is fish. Herons will also consume amphibians, reptiles, small mammals, crustaceans, and insects, and egrets supplement their diet in a similar manner, consuming insects, spiders, mollusks, small mammals, and amphibians.
Appearance and Size
There are various morphological differences between herons and egrets, some of which can be seen with the naked eye, while others are hidden deep beneath the feathers. One of the most obvious variations between these two types of birds is the size: herons are typically taller and heavier than egrets.
Some key defining features of both herons and egrets are the short tail and moderately long wings, as well as the long, thin legs. Herons typically have straight, thick bills, while egrets’ bills are much more slender. In addition, although the heron’s neck is long and slim, it is still much thicker than that of the egret, which is more delicate in appearance.
Members of Ardeidae have large feet to spread their weight on certain substrates and prevent them from sinking. Some species have webbing between the outer and middle toe; however, this does not seem to relate to which genus they are a member of – both herons and egrets can possess this feature. A distinguishing feature of both herons and egrets is the development of ornamental plumes during breeding season; these are usually seen on the back, breast, and head.
As well as the external differences, herons and egrets differ in their skeletal morphology. The shape of the posterior palatine, which is part of the facial skeleton differs between the two genera. Members of Egretta also have a prominent iliac recess (part of the pelvis), whereas in Ardea this is shallower.
Reproduction
Herons and egrets are both known to nest colonially, a strategy that has a number of benefits, such as protection from predators, and also increased foraging efficiency (due to there being greater numbers of birds available to find food). The colonies are usually situated in trees or shrubs near a body of water.
Species in Ardea and Egretta lay between three and five eggs, which are tended to by both parents. The young are altricial, and the adults feed them by regurgitating food – they bring a variety of prey, including large items such as eels and mammals, and smaller creatures such as insects and crustaceans. Egrets tend to breed in warmer climates, while herons can be more flexible in their temperature preferences.
Threats and Natural Predators
Both heron and egret populations face threats. While some species are thriving (for example, the little egret, whose numbers are increasing) others, such as the black-crowned night heron, are in decline. The main reason for these losses is due to the degradation of habitat, which often results from development, agriculture, and pollution.
As Egretta and Ardea are fairly large birds, herons and egrets are typically taken on by larger predators. In North America, this can include bears, eagles, hawks, and coyotes. As well as taking adult individuals, many predators will also target nests for eggs and young – crows, kites, raccoons, and foxes are common culprits.
