Great Blue Heron in Flight at Lake Arlington

The Great Blue Heron — the tallest bird you’ll see in Arlington Heights — is commonly found near the shore of Lake Arlington.

The Great Blue Heron, Ardea herodias, is a wading bird of the heron family Ardeidae, common all over North and Central America in Alaska, Quebec and Nova Scotia, as well as the West Indies and the Galápagos. The Great Blue Heron is not found in deserts and high mountains where there is no wading water. The Great Blue Heron — the largest North American heron —  is very similar to the European Grey Heron.

Great Blue Herons can be found in a range of habitats, in fresh and saltwater marshes, mangrove swamps, flooded meadows, lake edges, or shorelines, but they always live near bodies of water. Generally, they nest in trees or bushes that stand near a body of water.

Feeding and Diet
Great Blue Herons feed in shallow water or at the water’s edge during both the night and the day, but especially around dawn and dusk. Herons locate their food by sight and generally swallow it whole. Herons have been known to choke on prey that is too large. It uses its long legs to wade through shallow water, and spears fish or frogs with its long, sharp bill. Its diet can also include insects, snakes, turtles, rodents and small birds.
It is generally a solitary feeder. Individuals usually forage while standing in water, but will also forage in fields or drop from the air, or a perch, into water. As large wading birds, Great Blue Herons are able to feed in deeper waters, and thus are able to exploit a niche not open to most other heron species.

Great Blue Herons are known to be a problem for homeowners who have backyard ponds with Koi or other fish as their stock can become victims of hungry Great Blue Herons. Koi’s bright colors put them at a severe disadvantage against predators. Herons can empty a pond of its fish. A well-designed outdoor pond will have areas too deep for herons to stand in, and shade trees overhead to block the view of aerial passersby.

Breeding
This species usually breeds in monospecific colonies (contains only one known species), in trees close to lakes or other wetlands; often with other species of herons living nearby. These groups are called heronry (more accurately than “rookery”). The size of these colonies may be large, ranging between 5 – 500 nests per colony, with an average of approximately 160 nests per colony.

Great Blues build a bulky stick nest, and the female lays three to six pale blue eggs. One brood is raised each year. If the nest is abandoned or destroyed, the female may lay a replacement clutch. Reproduction is negatively affected by human disturbance, particularly during the beginning of nesting. Repeated human intrusion into nesting areas often results in nest failure, with abandonment of eggs or chicks.

Both parents feed the young at the nest by regurgitating food. Parent birds have been shown to consume up to 4 times as much food when they are feeding young chicks than when laying or incubating eggs.

Eggs are incubated for approximately 28 days and hatch asynchronously over a period of several days. The first chick to hatch usually becomes more experienced in food handling and aggressive interactions with siblings, and so often grows more quickly than the other chicks.

Migration
Birds east of the Rockies in the northern part of their range are migratory and winter in Central America or northern South America. From the southern United States southwards and on the Pacific coast, they are year-round residents.

Species and Scientific Classification Information
The herons are wading birds in the Ardeidae family. Some are called egrets or bitterns instead of herons. Within the family, all members of the genera Botaurus and Ixobrychus are referred to as bitterns, and—including the Zigzag Heron or Zigzag Bittern—are a monophyletic group within the Ardeidae. However, egrets are not a biologically distinct group from the herons, and tend to be named differently because they are mainly white or have decorative plumes.

The classification of the individual heron/egret species is fraught with difficulty, and there is still no clear consensus about the correct placement of many species into either of the two major genera, Ardea and Egretta. Similarly, the relationship of the genera in the family is not completely resolved. For example, the Boat-billed Heron is sometimes classed as a heron, and sometimes given its own family Cochlearidae, but nowadays it is usually retained in the Ardeidae.

Although herons resemble birds in some other families, such as the storks, ibises and spoonbills, they differ from these in flying with their necks retracted, not outstretched. They are also one of the bird groups that have powder down.

The members of this family are mostly associated with wetlands, and prey on fish, frogs and other aquatic species. Some, like the Cattle Egret and Black-headed Heron, also take large insects, and are less tied to watery environments. Some members of this group nest colonially in trees, others, notably the bitterns, use reed beds.

The Great White Heron, which was long thought to be a separate species, is a white morph of Great Blue which occurs in southern Florida. It is mainly found near salt water. Wurdemann’s Heron is an intermediate morph, in which only the head is white. The Great White Heron could be confused with Great Egret but is larger, with yellow legs as opposed to black. The Reddish Egret and Little Blue Heron could be mistaken for the Great Blue Heron, but are smaller, and lack white on the head and yellow in the bill.