Birds
Great Blue Heron
Ardea herodias · also called great blue heron
The great blue heron is the tall grey-blue statue standing in the shallows of nearly every North American wetland — motionless for minutes at a time, then, without warning, spearing a fish with a strike almost too fast to see. It is the continent’s largest heron, and its patience is its main weapon.
Overview
Great blue herons live in wetlands, lake and river edges, estuaries, and coasts across most of North and Central America, from Alaska to Panama and the Galápagos. Northern birds migrate; many are year-round residents. Despite standing well over a metre tall with a two-metre wingspan, a great blue heron weighs only 2–3.5 kilograms — hollow bones and feathers — and flies with slow, deep wingbeats, neck folded into an S.
The ambush
The heron hunts by standing still or wading slowly, then firing its head forward on a neck built around a modified sixth vertebra that works like a spring. Small fish are grabbed; large ones speared and then flipped to go down head-first. It also stalks voles, gophers, snakes, and frogs on land, and hunts by day and night.
Powder-down grooming
Instead of relying only on preen oil, herons have patches of powder down — feathers whose tips crumble to a fine powder that the bird works through its plumage with a serrated comb claw to absorb fish slime and oil, then combs out.
Nesting
Great blue herons nest colonially in heronries — stick platforms high in trees, often on islands or over water — from a few pairs to several hundred.
Status
The great blue heron is Least Concern and stable to increasing, helped by beaver ponds, reservoirs, and legal protection of colonies. It can be a nuisance at garden ponds and fish farms, where only non-lethal deterrents are permitted.
Great Blue Heron: common questions
How does the great blue heron catch fish?
By patience and a very fast strike. The heron takes up a position in shallow water or at the edge and either stands completely still or wades forward at a glacial pace, watching the water. When a fish comes within range, it uncoils its neck and drives its bill forward almost too quickly to see — a movement made possible by a modified sixth neck vertebra that acts like a spring-loaded hinge. Small fish are simply grabbed; larger ones are speared, then juggled around and swallowed head-first so the fins fold back. Herons hunt day and night and adjust their technique to the prey, sometimes standing over deep water from a log or dock, sometimes stalking voles across a dry meadow.
Can a great blue heron choke on a fish that's too big?
Yes, and it happens. Great blue herons are ambitious swallowers and will attempt fish that look far too large for their slender necks, working them down over many minutes. Usually this succeeds, but there are documented cases of herons dying with a fish lodged in the throat, unable to swallow it or bring it back up. The behaviour persists because taking a large fish when the opportunity arises is usually worth the risk — a single big catch can feed the bird for a day.
What is "powder down" and why does the heron have it?
Herons and their relatives have special patches of feathers on the chest and rump that grow continuously and never moult; instead, their tips disintegrate into a fine, talc-like powder. The heron works this powder through the rest of its plumage using its bill and a comb-like serrated claw on the middle toe of each foot. The powder absorbs fish slime, oils, and grime picked up while wading and feeding, and the bird then combs out the soiled powder, keeping its feathers clean and water-repellent. Most birds do this job with preen oil from a gland; herons largely use powder instead.
Are great blue herons a problem at garden ponds and fish farms?
They can be. A great blue heron will readily take ornamental koi and goldfish from a backyard pond and can clear a small pond in a few visits, usually at dawn. At commercial fish farms and hatcheries they are a recognised cause of stock loss. Because the birds are protected under the Migratory Bird Treaty Act in the US and similar laws elsewhere, control is limited to non-lethal deterrents — netting over the pond, motion-activated sprinklers, decoys (of limited effect, as real herons may just join them), and providing deep, steep-sided areas where a wading heron cannot stand.