The Great Blue Heron is the largest and most widely distributed wading bird of North America.

Great Blue Herons have variant forms one of which is white. The white morphs are usually found only in marine habitats. Though they tend to be colonial, some Great Blue Herons are solitary. Vagrant Great Blues have been observed in such places as the Arctic, Greenland, the Azores, Spain and the West Indies.

Though varying in size, when standing with head raised, Great Blue Herons average about four feet tall. Their wingspan is about 70 inches. In flight they are easily distinguished from flamingoes and cranes which fly with heads and necks extended whereas the head of the Great Blue Heron, except on takeoff and landing, rests upon a neck which is folded back, not extended. In flight, the legs trail behind and, because of the bird’s very short tail, serve as a rudder.

Males tend to be slightly larger than females. It is not unusual to see these herons standing on one foot with the other hidden in the lower body plumage. They also, at times, fold the neck so that the head rests on the shoulders.

Adult plumage is attained in their second year. In breeding season, the plumes on the back of the Great Blue are relatively short. However, the plumes of the crest and foreneck tend to be longer and more pronounced.

The diet of Great Blue Herons is largely opportunistic. Besides fish, frogs, small turtles and crustaceans, they also eat mice and other small rodents as well as snakes, nestling birds and possibly insects. Their preferred food is fish. They have been observed swallowing fish having a length of two feet.

Great Blues breed colonially in all the 48 contiguous states. The colonies vary in size some of which include other species. However when this occurs the great Blue Heron nests are usually found higher up. Though they do tend to select the highest point of whatever tree or bush they choose to nest in, on occasion, they have been known to nest on the ground and from time to time numerous nests have been found in a single tree.

Incubation of Great blue eggs takes 28 days. Both parents brood the eggs. Once hatched the young are fed regurgitated food until able to eat small fish. Young Great Blue Herons remain in the nest until they are as large as adults. Mortality rate for nest bound young is quite high.

The literature reveals that Great Blue Herons are at times the victims of a kind of avian “piracy” which is defined as the harrasment of one bird by another to force the victim to give up food. Accordingly, Great Blue Heron nestlings have been observed under harassment by Turkey Vultures as they force the nestlings to regurgitate their most recent meal which is then ingested by the vultures to feed to their own young.

During breeding season Great Blue Herons are known to fly considerable distance (6 miles or so) in search of food for themselves and their young. Presence at a particular place in a county regularly during breeding season may, but does not therefore necessarily, indicate the presence of a rookery. No known rookeries have been found recently in either Grand Traverse or Leelanau Counties. There is however at least one in Benzie County.

Mature Great Blue Herons have few natural enemies. Its large pointed beak is a daunting weapon. Nevertheless, because of its conspicuous size, it is often the target of thoughtless humans looking for something trophy-like to shoot at.

The Great Blue Heron is partially migratory. Generally it withdraws from the northern portions of its breeding range in winter except along the coasts.

Though most Great Blue Herons migrate, a few remain in Michigan through the winter months if there are places with open water and food sources. Migratory herons return to Michigan in mid to late March with courtship and nest building occurring for the most part in April and early May. Most Lower Peninsula young Great Blue Herons are sufficiently mature to leave the nest by the end of July. Migration begins in late summer and continues through October.

~bob c.