Great Blue Heron
Timmi Claveria (2001)

The Great Blue Heron, Ardea herodias, is the largest heron in North America. A member of the Ciconiiforme Order and the Ardeidae Family, the Great Blue Heron has between 4 and 8 subspecies. The one found along the northwest corner of North America is A. herodias fannini. Because of their long legs and neck and their grey body, Great Blue Herons are often miscalled cranes. However, Great Blue Herons, and other herons for that matter, have longer bills than cranes and fly with their neck folded back on their shoulder. Herons extend their necks only when they are about to take to the air or when they are under attack.

Other distinguishing characteristics of the Great Blue Heron are that it is about 48” tall, 38” in length, and has a wingspan of 70”. Their back and wings are a blue-green-grey color, and they have a white crown and face. Their foreneck and chest are black and white. Their undersides are whitish with black streaking on the belly. They have black shoulders and black plumes extending from above and behind the eyes to beyond the back of their head. There is no sexual dimorphism between the sexes, but males are generally larger than females. Immature Great Blue Herons have a black cap, a brownish-grey back, brownish-grey upperwings, and no black plume behind the eye.

With their long lets, herons are adapted for walking in the water. It’s habitats include marshes, streams, lakes, rivers, lagoons, mangroves, swamps, seacoasts, and sometimes even dry upland fields where they will catch small rodents. They can usually be found in any type of wetland where tall trees, rocky ledges, or dense reeds form safe havens for heronries. Their range includes all of North America except the northern tundra and forest belts, and extends to northern South America, the West Indies, and the Galapagos Islands. Great Blue Herons can be found throughout Oregon, and I have even spotted one standing in Willamette University’s Quad.

In it’s habitats, the Great Blue Heron eats a wide range of aquatic animals and insects, including fish, frogs, salamanders, lizards, snakes, shrimp, crab, crayfish, dragonflies, grasshoppers, and others. Great Blue Herons are patient predators and will sit motionless while waiting for their prey, their long necks drawn back into an “s” shape. It wades through the water on its long legs and in addition to waiting for their prey, they will stalk their prey, too. Prey are usually grasped by the Great Blue Heron, but sometimes are impaled by their sharp beak. Great Blue Herons feed during the both the day and the night, but are most active at dawn and dusk.

Although the Great Blue Heron tends to be a solitary feeder (except where food is very abundant, and then a number of herons can be found together), it congregates with other Great Blue Herons to nest. Choosing areas that are protected from strong wind and human disturbance, the herons usually nest in the tops of trees, in reeds, or on the ground. The female builds the nest out of sticks that the male has collected. Several hundred pairs may build nests in one popular heronry, or 1-2 pairs may be found in a less desirable location. The heronries are used year after year until human disturbance drives the birds away or the tree or nesting site falls or naturally degrades. Great Blue Herons breed between March and May in the northern hemisphere, and just before breeding season, males will strut their stuff for the ladyfolk, trying to impress them with so-called “dignified” postures that challenge their rivals. Sometimes attacks will ensue between males in which they seem to fence each other with their beaks. At the end of such displays, each male will leave in a pair with their mate after which they become fairly peaceful. Such displays are generally limited to coastal populations of the birds.

Once the honeymoon is over and parenthood sets in, both parents incubate the clutch of 3-7 bluish-green eggs for roughly 28 days. After birth, the chicks are fed a diet of regurgitated food. After 2 months, the chicks are no longer dependent on their parents for food. However, they will still call home for money when they are broke.

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Great Blue Heron, [Online] Available: http://www.mbr-pwrc.usgs.gov/id/fram1st/Idtips/h1940id.html [April 16, 2001]

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