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Wildlife Wonders

Today is Great Blue Heron Day!

Standing at 4 1/2 feet tall, with a wingspan of up to  6 1/2 feet the Great Blue Heron (Ardea herodias) is the largest of the North American herons.  Herons, egrets and bittern are all in the same family.  When seen flying over head they look almost prehistoric with their very slow wing beats, tucked in neck and long trailing legs.  On take-off their long necks will be outstretched, but will be tucked into a compact “S” shape during flight. 

Wading gracefully in the water, their long legs and widespread toes allow them to move with very little disturbance to the water, stopping and suddenly appearing statue-like and then like a bolt of lightning striking their prey with their long, thick dagger-like bill.  Great blue herons eat mostly fish, but will consume anything in striking distance including amphibians, reptiles, small mammals and other birds.  Herons sometimes spear large fish with their 5″ long bill and then maneuver it so it can be swallowed whole, head first.  Acidic stomach secretions soften the bones.  Similar to owls they sometimes “cast”, regurgitate, indigestible parts of prey in pellets. 

Great blue herons are blue-gray and have a wide black stripe over the eye.  Their shaggy appearance is due to long plumage on top of their head and on the chest and wings.  Males and females look the same and the only way to really tell the difference is by DNA testing or observing behavior.

Great blue herons live in both freshwater and saltwater habitats and generally breed in colonies, heron rookeries, that can consist of 500 or more individual nests.  The nest sites are chosen by the males and are highly variable.  Usually nests are found in trees 20-60 ft. above ground, but they can be on the ground or 100′ up in a tree.  Once the male selects a site he displays in the tree to attract a female.  After mating the male then collects the sticks and presents them to the female.  The female builds the nest that can be anything from a simple 20 inch platform to an elaborate nest measuring 4 ft. across and 3 1/2 ft. deep, lined with pine needles, leaves, moss or grasses. Generally 2-6 pale blue eggs are laid in the nest and incubated by both parents.  The eggs are rolled regularly to maintain an even 98-100oF temperature and so that the embryos don’t stick to the inside of the shell.  Incubation lasts about 25-30 days.  Egg shells are porous so oxygen gets into the egg through the pores. 

Through the process known as “pipping” the chick breaks through the egg with a hard projection on the bill called the egg tooth. The hole is enlarged by the chick to finish hatching. The chicks are fed by both parents.  Newly hatched chicks weigh about 1 3/4 ounces, at 1-2 weeks they are about 6 inches, 2-4 weeks at 12 inches, and in 4-6 weeks they are almost 4 feet!

Young are capable of flight at 60 days and depart the nest at 65-90 days.  The fledglings may return to the nest for the next 3 weeks.  Some birds use the same nest year after year and others build new nests each year.  The oldest known great blue heron was 23 years old, but most wild birds lifespan is much shorter. 

Great blue herons communicate in various ways.  Both males and females snap their bill tips together as part of territorial and breeding displays.  Sometimes sibling rivalry develops among nestlings and they will jab each other with their bills.  This can be a result of competition for food or just to hone their skills.  Great blue herons also use vocalizations.  At breeding grounds when a partner lands back at the nest they are greeted with squawking “roh-roh-rohs”, a disturbance will lead to clucking “go-go-gos” folled by a rapid “frawnk” squawk.

Not all great blue herons migrate great distances, but most move southward to open water.  Some northern population, east of the Rockies, migrate to the Caribbean, Central America or northern South America. They usually leave the breeding grounds in mid-September to late October and return by February or March.

Herons are protected by the Migratory Bird Treaty Act.  Great blue heron numbers have been stable or on the rise, depending on the area, since 1966 and can be found throughout North America.  Previously they were shot for “target practice” or hunted for feathers, eggs and meat in the late 19th century.  Population decline is still seen in some local areas attributed to elevated mercury  and PCB levels in waterways.  Since they depend on wetlands and relatively undisturbed sites for breeding they are vulnerable to habitat destruction and human disturbance.  Bald eagles and great horned owls are predators of great blue herons. 

Great blue heron rookeries can be found throughout Connecticut one location is along the CT River in Portland, but great blue herons can most certainly be found at Hammonasset Beach State Park. 

Resources

Great Blue Heron Identification – All About Birds

https://www.allaboutbirds.org/guide/Great_Blue_Heron

CT Audubon – Bird Finder Great Blue Heron

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