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Great Blue Heron
Herons & Egrets · Partial migrant

Great Blue Heron

Great Blue, Blue Heron · Ardea herodias

Least Concern91–137 cm · 1820–2700 g

By the Birdfact teamChecked byNathan Cope

Poised to strike, this large heron stalks along American waterways in search of fish and other small animals. These widespread waterbirds are among the tallest of North America’s birds.
On this page13 sections
  1. How to recognise it
  2. Its size
  3. Its song and calls
  4. When and where to see it
  5. What it eats
  6. Nesting and breeding
  7. Behaviour
  8. Lifespan and predators
  9. Conservation
  10. More photos
  11. Great Blue Heron guides
  12. Quick facts
  13. Sources

How to recognise it

Great Blue Herons are large, distinctive American waterbirds. Continue reading to learn their most important identifying features.

What do Great Blue Herons look like?

Great Blue Herons vary in appearance across their range. All are tall, upright birds with long legs and a long, S-shaped neck and head. They have large, dagger-like bills and a long, thin crest at the back of their head.

Most Great Blue Herons are blue-gray overall, with a white crown, prominent black stripes across the top of the head, a white face, and a yellow bill and eye. However, several subspecies are recognized, and interestingly, the birds from Florida, the Caribbean, and southeast Mexico have all-white plumage.

Male and female Great Blue Herons look alike, although males develop longer plumes in the breeding season. Look for these attractive, elongated feathers on the chest/lower neck and back. Juvenile and immature birds resemble adults but have shorter, duller plumage and dark gray rather than white crowns.

Great Blue Heron flying low of a Florida bay
Great Blue Heron flying low of a Florida bay

The Great Blue Heron is one of America’s tallest birds and one of the largest species in its family. Males are typically larger than females.

Length

Great Blue Herons stand about 4 feet (1.2 m) tall. They have a total body length of 38 to 54 inches (97 - 137 cm). The biggest individuals occur in the Southeast of their range.

Weight

Great Blue Herons weigh 4 ½ to 5 ½ pounds (2 - 2.5 kg). The males are significantly heavier than the females.

Wingspan

These birds have a wingspan of 5 ½ to 6 ½ feet (1.7 - 2 m).

Great Blue Heron fishing in the sea
Great Blue Heron fishing in the sea

Its size

Adults
Length
91–137 cm
Wingspan
167–201 cm
Weight
1820–2700 g

Its song and calls

Birds from the Heron family are not known for their singing abilities, and the Great Blue Heron is no exception. Keep reading to learn more about their vocalizations.

What sound does a Great Blue Heron make?

Great Blue Herons produce a variety of raucous calls, ranging from a series of brief squawks to more prolonged low-pitched grunts. These birds tend to vocalize most frequently in the breeding season when greeting their partner or when disturbed.

When and where to see it

North America

OctoberIn season

Last month in 4 places

Most recorded in October

  1. 1. Oklahoma2.4%
  2. 2. Mississippi2.0%
  3. 3. Arkansas1.9%
  4. 4. Kansas1.8%
  5. 5. Washington1.8%

Each dot is a county, state or province: the bigger and darker, the larger the bird’s share of that place’s bird records that month. Grey dots: no regular records. The ringed point is the centre of the bird’s records this month; the arrow shows how it moved since last month, and the dashed loop its path through the year. “Arrivals” colours places where it becomes regular this month (orange) or is in its last regular month (grey). GBIF eBird Observation Dataset, 2019–2024. Map data: Natural Earth, US Census Bureau; place centres © OpenStreetMap contributors.

In your area

See when the Great Blue Heron is recorded in your county, state or province.

or

How often the Great Blue Heron turns up in the United States and Canada through the year, from birdwatchers' records.

United States

Resident · all year · most records in August

Canada

Resident · all year · most records in August

Regularly recordedOccasionalBar height: share of all bird records that month
Show as a table
MonthUnited StatesCanada
January1.2% (regular)0.46% (regular)
February0.97% (regular)0.42% (regular)
March0.96% (regular)0.49% (regular)
April0.96% (regular)0.78% (regular)
May0.86% (regular)0.72% (regular)
June0.92% (regular)0.81% (regular)
July1.2% (regular)1.2% (regular)
August1.5% (regular)1.6% (regular)
September1.4% (regular)1.6% (regular)
October1.3% (regular)1.3% (regular)
November1.3% (regular)0.86% (regular)
December1.2% (regular)0.50% (regular)

Worldwide: recorded regularly in 44 countries

Countries where it was recorded in at least 3 of the 6 years 2019–2024. Linked countries have their own bird list.

Europe (1)
North America (40)
South America (3)

Great Blue Herons are one of the most widespread waterbirds in North America. Read on to learn more about where they live.

What is the habitat of a Great Blue Heron?

Great Blue Herons are aquatic birds that occur wherever shallow water and fish are available. They hunt along streams, rivers, marshes, swamps, ponds, lakes, mangroves, and coastal areas.

It's not unusual to find them hunting away from water in pastures, grassy areas, and prairie.

What is the range of a Great Blue Heron?

Great Blue Herons occur from Central America and the north coast of South America to the south Coast of Alaska. Birdwatchers in the US can spot these birds in each of the Lower 48 states, although they are absent in the winter in some parts of the Midwest and Northeast.

They visit the South of Canada to nest, but resident populations occur along the west coast of British Columbia.

Great Blue Heron wading through the water, in its natural habitat
Great Blue Heron wading through the water, in its natural habitat

Where do Great Blue Herons live?

Great Blue Herons spend their time standing motionless or stalking along the shore of water bodies. They usually fly up to the safety of tall trees to sleep at night. In the nesting season, both sexes spend most of their time at the nest when not out hunting.

How rare are Great Blue Herons?

Great Blue Herons are not a rare species. Birdwatchers have a good chance of spotting these impressive birds in just about any aquatic habitat in North America.

Blue Heron flying low over a swamp, with prey in beak
Blue Heron flying low over a swamp, with prey in beak

Migration

Birds are mobile creatures that can move long distances in response to changing seasons. Great Blue Herons have varying strategies for dealing with the winter cold.

Do Great Blue Herons migrate?

Great Blue Herons are partial migrants. In areas where waterways remain ice-free, these birds can make a living throughout the year since their food source remains relatively abundant.

For example, individuals that nest in Canada must head south for warmer climates. However, those that live along the Pacific coast as far as Alaska can persist since the coastal waters provide year-long hunting opportunities.

Birds that migrate south may overwinter in the Lower 48 or travel as far south as the Caribbean and the north coast of South America.

Tips for seeing it

  • Look for them in wetlands, along shorelines, and in shallow waters
  • Observe early morning or late afternoon when they're most active
  • Listen for their distinctive harsh squawk
  • In flight, note their large size and S-curved neck
  • Check for nesting colonies in tall trees near water bodies

What it eats

Great Blue Herons are carnivores that are capable of swallowing surprisingly large animals. These fierce birds use stealth, speed, and an impressive spear-shaped bill to catch their prey.

What do Great Blue Herons eat?

The Great Blue heron is, first and foremost, a fishing bird. They prefer to wade in shallow waters, poised to strike at fish up to about two feet long. However, these birds will not pass up the opportunity to hunt other prey like rodents, frogs, invertebrates, and smaller birds.

What do baby Great Blue Herons eat?

Baby Great Blue herons eat the same food as their parents - primarily fish. They are fed by regurgitation when the parent bird inserts its bill into the chick's open mouth, but they will also pick up food items deposited on the floor of the nest. Both parents feed the chicks.

Great Blue Heron catching a large fish
Great Blue Heron catching a large fish

Nesting and breeding

Great Blue Herons nest in the spring and summer, sometimes starting in the late winter. Both parents work together, usually producing a single clutch of two to six eggs, although second clutches have been recorded.

Where do Great Blue Herons nest?

Great Blue Herons nest across most of the Lower 48 states, southern Canada, and up to the south coast of Alaska. Pairs usually build their nests in trees, although they will nest on the ground on islands where they are safe from predators.

They typically nest in large colonies of up to 1000 pairs, although they will also nest alone.

What do Great Blue Heron eggs look like?

Great Blue Herons lay two to six pale blue eggs. Most eggs measure 61 to 65 mm (about 2 ½ inches) long and 45 to 46 mm (about 1¾ inches) wide.

Do Great Blue Herons mate for life?

Great Blue Herons do not mate for life, although they are monogamous during the nesting season. Pairs work together to raise their young but pair up with new partners in successive years.

Nesting neighbors - Great Blue Herons nesting next to each other high up a tree
Nesting neighbors - Great Blue Herons nesting next to each other high up a tree

Behaviour

Great Blue Herons are fascinating birds to observe, especially when hunting and during the nesting season. These birds may have an intimidating appearance, but bird watchers have little to fear from them.

Are Great Blue Herons aggressive?

Great Blue Herons are not aggressive toward humans, although they may strike out in self-defense if captured or cornered. They are generally peaceful towards their own species, although fights have been recorded on rare occasions.

Great Blue Herons may claim small territories in prime hunting areas, although they defend these areas with displays and chases, rarely engaging in physical combat.

Great Blue Heron wading through marshland swamp
Great Blue Heron wading through marshland swamp

Lifespan and predators

Despite their large size, Great Blue Herons do not have a particularly long life expectancy and are not immune to predation.

How long do Great Blue Herons live?

Great Blue herons can live for over twenty years. The oldest known individual lived to be 24 years and six months old. However, most will not live to see their first birthday, and those that reach maturity probably survive about five years on average.

What are the predators of Great Blue Herons?

Despite their large size and weapons, Great Blue Herons are vulnerable to some predators, including Bald Eagles. Their eggs and nestlings are eaten by a greater variety of birds and mammals, including Crows, Ravens, Turkey Vultures, Bears, and Raccoons.

Are Great Blue Herons protected?

Great Blue Herons are protected in the United States by the Migratory Bird Treaty Act of 1918. As such, it is a crime to harm, trap, or kill these magnificent waterbirds.

Are Great Blue Herons endangered?

Great Blue Herons are not endangered. This common and widespread species is considered to be increasing and the IUCN (International Union for Conservation of Nature) lists them as a ‘Least Concern’ species.

Great Blue Heron hunting for fish
Great Blue Heron hunting for fish

Conservation

While the Great Blue Heron is currently listed as Least Concern, it faces threats from habitat loss and degradation of wetlands. Conservation efforts focus on protecting and restoring wetland habitats, as well as reducing pollution in aquatic ecosystems where these birds feed and breed.

More photos

3 photos

Great Blue Heron guides

5 guides

Quick facts

Length
91–137 cm
Wingspan
167–201 cm
Weight
1820–2700 g
Lifespan
15–20 years
Migration
Partial migrant
Global status (IUCN)
Least Concern
World population
500,000 - 4,999,999 mature individuals
Population trend
Increasing
Also called
Great Blue, Blue Heron
Scientific name
Ardea herodias

Sources

3
  1. 1BirdLife International. 2020. Ardea herodias. The IUCN Red List of Threatened Species 2020: e.T181500967A181565357. Source (opens in a new tab)
  2. 2Partners in Flight (2019)
  3. 3Partners in Flight (2019)
Spotted a mistake?Tell usHow we write and checkBy the Birdfact team · Updated

Checked by

Nathan Cope, founder and editor

Nathan founded Birdfact and leads its writers and contributors in the UK, the US and Canada. He has watched and studied birds for more than ten years, and checks every article and species guide before it’s published.

How we write and checkAbout Nathan