On the face of it, herons and cranes might seem to be quite similar to each other in many ways. While they do share common ecological and morphological features, there are also a number of differences between these two groups of birds.
The differences begin at a classification level; while both herons and cranes are in the class Aves (birds), they diverge at the order level, with cranes being in the family Gruidae, which is a part of the order Gruiformes, and herons being in the family Ardeidae, which is a part of the order Pelecaniformes.
Distribution, Habitat, and Diet
Both cranes and herons have very wide distributions. Herons occur on all continents except for Antarctica, and cranes follow a similar pattern but are also absent from South America. The greatest diversity of cranes is found in Asia, followed closely by Africa. Herons are most diverse in the tropics.
While herons are typically found near bodies of water such as rivers, lakes, or ponds, cranes often prefer grasslands and fields – although they may frequent wetlands as well. It is worth noting that the two groups do not always ‘stick to the rules’ around habitat use, and it is not unusual to spot herons in agricultural fields.
Another clear distinction that can be made between these two groups of birds is that members of Gruidae cannot perch in trees, whereas members of Ardeidae can and frequently do. While herons are usually seen as solitary individuals foraging alone (usually by wading in shallow water), cranes tend to live in flocks and forage by walking slowly on land. All cranes are diurnal foragers, whereas herons can forage by day or night. Gray herons are typically diurnal, but species such as the black-crowned night heron are nocturnal.
Members of Ardeidae are carnivorous, consuming organisms such as fish, amphibians, insects, and small mammals. In contrast, members of Gruidae are omnivores, taking advantage of animal matter such as worms, insects, reptiles, and small mammals, as well as plant matter such as seeds, leaves, and nuts.
Appearance and Size
Cranes are larger than herons, with the sarus crane standing at 152 – 156 cm (5 ft – 5 ft 1 in) in height, whereas the goliath heron, which is the largest heron species, reaches just 120 – 150 cm (3 ft 11 in – 4 ft 11 in). The wingspans of these birds are 240 cm (7 ft 10 in) and 180 – 230 cm (5 ft 11 in – 7 ft 7 in) respectively. Cranes’ wings are broad and rounded in shape, but herons have more pointed, angular wings.
The two birds have different postures both when standing and in flight. The crane tends to stand taller, while herons may appear to be a little hunched. In flight, herons rarely raise their wings above horizontal, usually only lifting them to be parallel with the body, whereas cranes lift their wings right up above their backs. In addition, while the heron curves its neck in while flying, the crane keeps its neck outstretched.
While members of Gruidae usually have longer legs than herons, their necks are shorter, and they have short, robust bills (in contrast to Ardeidae’s long, dagger-like bills, which are used for spearing fish). Cranes produce a loud, rattling, ‘bugle-like’ call, which may be attributed to their coiled trachea. Herons, on the other hand, create a croaking, squawking, or shrieking sound.
Reproduction
There are numerous differences in the reproductive ecology of herons and cranes. Members of Gruidae are monogamous – in other words, they mate for life, whereas herons will usually select a different mate each breeding season.
Many species of crane take several years to reach sexual maturity, with the age at which this happens ranging from 3 – 8 years. Herons reach maturity much younger, usually at 1 – 2 years. This reflects their differences in lifespan, with herons typically living for 5 years, while cranes may live for up to 20 years in the wild.
Members of Gruidae have particularly elaborate courtship displays, with ‘prolonged bouts of dancing’. In contrast, many species of heron mate without any display at all, although they may perform territorial and pair-bonding behaviors in the vicinity of the nest.
Cranes are ground-nesting birds; they usually lay 1 – 2 eggs which are incubated by both parents. The chicks are precocial, leaving the nest soon after hatching, and the parents lead the clutch to food. Herons, on the other hand, nest in trees and, despite being solitary at other times, may nest in colonies. They lay 4 – 7 eggs, and the chicks are altricial, tended to by the parents until they are capable of flying and leaving the nest.
Threats and Natural Predators
Crane and heron populations face similar threats, such as habitat loss (particularly the degradation of wetlands and grasslands). In many areas, both groups of birds are also hunted, with hunters taking eggs and chicks as well as adults.
Some species, such as the black-crowned night heron, are also susceptible to the use of pesticides, as well as diseases such as avian influenza. Similarly, the whooping crane, which is endangered, is threatened by climate change causing adverse weather conditions such as drought, and parasites such as black flies.
