Black-crowned Night Herons: Not Your Typical Heron

When you think of a heron, you usually think of a diurnal wading bird that has long legs, a long neck and a long bill. Black-crowned Night Herons don’t possess any of these familial characteristics. Stocky and relatively short-legged and short-billed, these herons typically rest during the day and start actively hunting at dusk, continuing through the night.
Prey includes fish (half their diet) plus a wide range of other creatures including leeches, earthworms, insects, crayfish, snakes, turtles, small mammals, birds and frogs. The manner in which a Black-crowned Night Heron lures and captures its prey varies. Two of its most intriguing fishing techniques include bill vibrating (opening and closing its bill rapidly in the water to attract prey) and bait fishing – using bait to attract fish.
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Lingering Great Blue Herons
Most fish-eating birds that breed where most bodies of water freeze over in the winter migrate further south in the fall, including Great Blue Herons. Movement of this large wading bird takes place largely from September to mid-October. According to Christmas Bird Count data, the Great Blue Heron has the widest wintering distribution of any heron species in North America.
While the number of Great Blue Herons in the Northeast is greatly diminished in November and December, it’s not uncommon to spot lingering birds at this time of year. Come January, when most bodies of fresh water are inaccessible to herons, sightings become rare until they begin returning in March.
Where open water remains in the Northeast, those Great Blue Herons braving the cold continue to consume fish, insects, amphibians and crustaceans. Small mammals, especially voles, and birds remain a warm-month delicacy, when mammal hair is cast in pellets and bones are digested.
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Silver Lining to Low Water Levels
The low water level of most small ponds and streams this fall has at least one silver lining, and that is that consumers of fish and other aquatic creatures expend far less energy finding prey, for it is all concentrated in much smaller bodies of water. The few puddles of water in small streams contain a vast amount of life, as do small ponds.
The Great Blue Heron has the advantage of having a varied diet that is found in a variety of habitats, so it forages in grasslands, marshes, intertidal beaches, riverbanks and ponds. While amphibians, invertebrates, reptiles, mammals, and birds are all known to have been eaten by Great Blue Herons, fish are their mainstay. They often forage in ponds, where they typically wade or stand in wait of prey in shallow water, which has not been in short supply this summer and fall. While the low water level is wreaking havoc with beavers and muskrats, it provides bountiful fuel for herons, egrets, kingfishers and other birds that forage in small ponds and streams as they wend their way southward.
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Green Herons Migrating
Green Herons (Butorides virescens) are small, crested, wading birds that inhabit wetland thickets throughout most of North America. After breeding, most tend to wander to more favorable foraging areas before migrating south to Florida, Central and South America. Migration begins in late August/early September and by mid-October, most Green Herons have departed.
Green Herons are among the few species of birds that use tools in order to lure fish to within their striking distance. Bread, mayflies, twigs, leaves, berries, earthworms and feathers are among the lures they have been observed dropping into the water as bait. To watch a video of a persistent and successful Green Heron fishing with a lure, go to https://www.youtube.com/watch?v=Porp5v5lLKk .
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Great Blue Herons Cooling Off
Birds have a number of ways of keeping cool. They don’t sweat, nor do they pant, but birds do have several behavioral adaptations which reduce their temperature. Often nestlings that are exposed to the relentless heat of the sun for long periods of time, such as platform-nesting raptors and herons, resort to what is called gular fluttering. They open their beaks and “flutter” their neck muscles, promoting heat loss – an avian version of panting.
Another avian strategy for cooling off is demonstrated by this adult Great Blue Heron — that of arranging its wings in a certain position in order to reduce its body heat. Great Blue Herons droop their wings while standing, which allows air to circulate across their body and sweep away the excess heat.
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Great Egrets Dispersing
Although Great Egrets breed sporadically as far north as Vermont, seeing one in northern New England is always noteworthy. The likelihood of a sighting increases as summer progresses, due in large part to the phenomenon of post-breeding dispersal. After young Great Egrets have fledged, individuals wander well outside their typical breeding range, as far north as southern Canada. The northward dispersal of juvenile birds peaks in August and September. Most Great Egrets migrate in the fall, from September through December.The extent of their migration is influenced by annual fluctuations in temperature. When winters are mild, individuals may remain as far north along the Atlantic Coast as Massachusetts.
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Juvenile Green Herons Becoming Independent
Green herons are typically solitary and secretive birds, but if you find one, you often have an extended period of time to observe it, as they often slowly stalk their prey, or pose statue-like, sometimes for minutes at a time, while waiting to strike at a fish, frog or invertebrate. Three characteristics tell you that the green heron in this photograph is a juvenile: the few tufts of down that remain on its head, its streaked neck (adults have solid rufous necks) and its yellow legs (adults have orange legs).
After fledging when about three weeks old, they can soon fly. The juvenile fledglings continue to be fed by the adults for a period of time and are taught how to forage for fish. Green herons are one of very few bird species that are known to occasionally use a tool (insects, earthworms, twigs, feathers) to catch their food – they simply drop the lure and wait for small fish to appear. (A wonderful video of a green heron successfully using bread for this purpose can be seen at https://www.youtube.com/watch?v=Porp5v5lLKk.)
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Great Blue Herons Mating
Numerous displays lead up to the mating of great blue herons – neck stretching, bill clacking, wing preening, circling flights, twig shaking, crest raising, neck fluffing, to name but a few. After this elaborate courtship comes copulation, which is not nearly as showy. Copulation typically takes place on the nest. The male places one foot gently in the center of the female’s back. The female leans forward, bends her ankles and holds her wings slightly away from her sides while the male lowers himself, often flapping his wings. Once the job is done, the male flies off. If you look closely you can perhaps make out that the male is grasping the female’s head/neck while copulation takes place.
Great Egret & Post-breeding Dispersal
Although Great Egrets (Ardea alba) do breed sporadically as far north as Vermont, seeing one in northern New England is always noteworthy. The likelihood of a sighting increases as summer progresses, due in large part to the phenomenon of post-breeding dispersal. After young Great Egrets have fledged, individuals wander well outside their typical breeding range, as far north as southern Canada. The northward dispersal of juvenile birds peaks in August and September. (This Great Egret is about to dine on a crayfish.)
How Great Blue Herons Stay Cool
Birds have a number of ways of keeping cool, which is a good thing, given the number of hot days we’ve experienced this summer, and probably for summers to come. They don’t sweat, nor do they pant, but birds do have several behavioral adaptations which reduce their temperature. Often, while exposed to the relentless heat of the sun, Great Blue Heron nestlings resort to what is called gular fluttering. They open their mouths and “flutter” their neck muscles, promoting heat loss – an avian version of panting. An even easier behavior to observe is the position Great Blue Herons will often assume on a hot day. They droop their wings (see photograph) while standing, which allows air to circulate across their body and sweep away the excess heat.
Great Blue Heron Fishing
Although Great Blue Herons are colonial nesters, they forage by themselves, usually by slowly wading or standing in wait of prey in shallow water. Fish are the mainstay of their diet, but they also consume amphibians, invertebrates, reptiles, mammals, and birds. When prey is located (by sight), the heron rapidly thrusts its neck forward and grabs it with its beak. If it is small, it is sometimes tossed in the air before it is swallowed, as the photograph depicts. Most prey are swallowed whole.
Juvenile Green Heron
Green herons are typically solitary and secretive birds, but if you find one, you often have an extended period of time to observe it, as they often slowly stalk their prey, or pose statue-like, sometimes for minutes at a time, while waiting to strike at a fish, frog or invertebrate. Three characteristics tell you that the green heron in the photograph is a juvenile: the tufts of down that remain on its head, its streaked neck (adults have solid rufous necks) and its yellow legs (adults have orange legs).
Great Blue Heron Chicks Yawning
I had to laugh recently when I noticed a chain reaction going on in a Great Blue Heron nest I was watching. There were five chicks, and one of them yawned. At least I presume it was a yawn, though perhaps it could have be re-aligning its beak or perhaps cooling off. Exactly like humans, each of the remaining four birds followed suit and proceeded to stretch their beaks open wide in succession. It struck me as quite comical, especially when I discovered myself yawning as I observed the heron chicks doing the same.
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