Wet & Wild May: Great Blue Heron With more than 75 acres of open water, birds live along the river, lakes, and streams at Duke Farms are truly “lucky ducks”. One of the most majestic of all the water birds encountered on the property is the great blue heron. This long-legged wader with blue-gray plumage can often be spotted standing motionless in the shallows as it scans the water’s edge for fish, snakes, and frogs. They can pose like statues for what seems an eternity, but when a meal wanders near, the great blue heron stalks and strikes like a stealth bomber. Thanks to specialized neck vertebrae they can snatch an unsuspecting creature with lightning speed.
The great blue heron is one of our tallest birds. It stands between 4 and 5 feet with a 6-foot wingspan, but only weighs about 6 pounds! It has long gray legs, a thin neck that it can curl into an s-shape, and an orange pointy bill that it wields like a sword to catch its prey. When it flies, the heron pulls its neck into a tight s-shape close to its body while its long legs dangle out behind. It’s understandable that pterodactyl comes to mind when the bird flies overhead.
Great blues live in both freshwater and saltwater habitats and usually forage alone. They are not picky eaters and will just as soon dine on small rodents, crustaceans, and insects as much as fish. Herons swallow their prey whole and can digest almost all parts of the creatures that they swallow, including the bones. In some cases, they will cast out indigestible pellets like owls do.
The sight of a heron struggling to swallow a whole writhing snake is awfully reminiscent of a sword swallower in a circus. Only the bird doesn’t have hands to assist with the struggle. It snatches the snake with its long beak and whips the snake down its throat!
Herons are found throughout most of the United States and coastal Mexico year-round. They also breed in Canada in the summer and winter all the way through central America. Most of the year great blue herons are spotted by themselves, but not so during the breeding season. Great blues nest in colonies called heronries. Sometimes a colony consists of just a few families but in some places more than 500 individual nests make up the colony! The birds mostly nest in trees with multiple nests in each tree. In wetland habitats where trees are scarce, they have been known to nest on the ground, in shrubs, and even on structures and artificial nest platforms.
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Males arrive at the colony and settle on nest sites in early spring. Courting and mating takes places somewhere between March and May. It’s up to the male to collect much of the nest material, mostly sticks gathered from the ground, shrubs, trees, or from unguarded and abandoned nests. He presents them to the female and if satisfied with the building materials, she will weave a nest. She makes a flattened platform of sticks with a bowl-shaped nest cup which she lines with pine needles, moss, dry grass, leaves, or small twigs. Nest building can take from 3 days up to 2 weeks and the finished nest can range from a just small platform to multi-year affairs that reach 4 feet across and nearly 4 feet deep.
Great blue herons appear blue gray from a distance, with a wide black stripe over the eye and black shoulders. In flight, the upper side of the wing is pale blue on the forewing and darker on the flight feathers. They have an amazing feather system that protects them from oily water. Specially adapted feathers on their chests continually grow and fray and as they fray, they create a powdery substance called powder down. Herons comb the down with a fringed claw on their middle toes (pectinate toes). Together the claw and powder act like a scrubby sponge and cleanser to remove fish slime and oils from their bodies as they preen.
During breeding, herons have long wispy plumes on the back and neck that flutter in the wind. The birds have elaborate courtship displays that include neck stretching and twining, greeting squawks, stick transfers, and showy moves where the birds hold their plumes erect and clap their bill tips. Breeding colonies are loud! The great blue heron doesn’t have a melodic song, but they make lots of noise. Pairs greet each other with loud croaks and long grunty roh-roh-roh calls, bill snapping, and clapping. If there’s any kind of threat or disturbance, the colony will erupt with frantic squawks and groans.
Herons lay 2 to 6 slightly pale blue eggs in the nest bowl. Incubation is about 28 days. Hatchlings are tiny fuzzy balls of grey feathers and are born with their eyes open. Both adults tend to the chicks and mostly feed them bits of fish, but they will feed them other creatures if fish are in short supply. Parents carry prey in their throat pouches to the nest and then regurgitate the meal into the nest for their young to eat. Young herons may vomit over the side of the nest when alarmed to discourage predators.
The nestlings fledge when they are around 7 to 8 weeks old. Parents attend to the young through the summer when the young birds disperse for parts unknown. Juvenile birds are just as big as full adults, but their feathers are blue-grey tinged with Juvenile great blue heron has brown coloring brown. Herons usually start mating behavior in their third spring mixed with the blue-gray feathers. or when they are about 22 months old.
Most great blue herons migrate to some extent but are often seen in New Jersey in winter. If they migrate, they generally move southward and always to places with open water. Migration usually occurs
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mid-September to late October and they return to their breeding colonies by February or March. Herons may migrate on their own, but they have also been seen in groups of up to 100 during migration. The young also migrate but it is unknown if young stay with parents during migration. Parents usually stop interacting with their young in August or September, right around the time when the young leave the area.
Great blue herons defend both nesting and feeding territories from other herons with threatening physical displays. The birds go after intruders with their head thrown back, wings outstretched, and bill pointing skyward. Crows and ravens will eat heron eggs. Eagles, raccoons, bears, turkey vultures, and red-tailed hawks prey on the young birds and sometimes even the adults. Birds often abandon a rookery if they have been attacked by predators.
Nesting in rookeries is a way for great blue herons to avoid predation. By nesting within a large group, there are many more eyes and ears to keep watch for predators. Also, the chances that one particular nest will be attacked decreases significantly when there is a high density of nests. Still, mortality of young birds is high in the first two years of life, but once they are adults they often live to be 15 year or more.
Like most birds, climate change is the biggest unknown when it comes to threats facing herons. As the climate warms, wetlands will be flooded, and they may lose their breeding territories. On the other hand, they may expand their range further north to the arctic. Here is a great online visualization tool to see what happens to their range as the climate warms.
Activity: Great Blue Heron Fishing Game Great blue herons have long sword shaped beaks that are ideal for probing mud and catching fish. Their beaks are called striking beaks. In this activity you will pretend you are heron striking your long beak into water to catch your dinner. This is a fun game to play with two or more players.
Materials:
Salad or pasta tongs = Small toys or natural materials heron beak Pail of water = pond stones, leaves, pinecones, twigs = meals Directions Watch this video of great blue heron hunting for a meal in the water. Listen to the sounds that great blue herons make Fill a bucket or pail with water. If possible, bring the game outdoors Place the small toys/natural materials like pinecones, stones, twigs, and leaves into the bucket
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Pretend you are great blue heron. Practice opening and closing your “beak” (salad tongs, chopsticks or two sticks joined together with a rubber band can also work, but you will need 2 hands to operate the sticks as a beak Stand 10 to 20 feet away from the pond (bucket of water) Pretend you are a heron and stalk your way to the pond mimicking the movements of the heron in the video you watched earlier. Move like a heron towards the bucket/”pond” When you reach the “pond” open your “beak” and stab it into the water. See if you can “catch” a “meal” on your first try. If not, how many tries does it take you to catch a meal? See if you can catch all the food in the bucket If playing with other people, take turns being the heron and sharing the materials See who catches the most meals or who takes the shortest time to catch a meal Make heron sounds together as if you were a colony of great blue herons!
Additional Resources All About Birds; Great Blue Heron Audubon; Great Blue Heron EBird; Great Blue Heron
*Photos courtesy of Macaulay Library, Cornell University, Ithaca NY.
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