The green heron (Butorides virescens) is a small heron that is found throughout much of North and Central America. It is a somewhat uncommon bird over much of its range, leading many birders to wonder – is the green heron rare?
Quick Facts on the Green Heron
- The green heron is a small heron species, measuring approximately 33-38 cm (13-15 inches) in length with a wingspan of around 58 cm (23 inches).
- It has a greenish-black cap and back, with a chestnut neck and wing plumes. The underparts are grayish with fine streaks and bars.
- Green herons are found from southern Canada through the United States, Mexico, Central America, and into northern South America.
- They inhabit wetlands, ponds, streams, and shorelines, often perching motionless to wait for prey.
- Their diet consists mainly of small fish, frogs, insects, rodents, and other small animals.
- Green herons are solitary nesters, with breeding pairs defending a small territory.
- Clutch sizes are usually 3-5 eggs. Incubation takes around 3 weeks and the young fledge in about 3 weeks.
- They are a migratory species, with northern populations migrating south for the winter.
Green Heron Population and Status
The green heron has an extremely large range across most of North America, and a global population estimated at 1.2 to 3.9 million birds. They are considered to be of ‘Least Concern’ on the IUCN Red List of Threatened Species. Their numbers did decline somewhat from the late 1800s to mid 1900s due to hunting pressure and wetland habitat loss, but populations rebounded after protective legislation was enacted.
Overall, the green heron remains a common to fairly common species over much of its range. However, its relatively secretive nature means it is not frequently observed by most casual bird watchers. Seeing or hearing one is often a special event for a birder. So while not rare from a conservation standpoint, the green heron is uncommon enough to create excitement when encountered.
Relative Abundance Across the Green Heron’s Range
The green heron’s abundance varies across different regions:
Canada
Green herons are found across southern Canada, north to southern British Columbia, Alberta, Saskatchewan, Manitoba, Ontario, Quebec, and the Maritime provinces. They are uncommon and local across this region, occurring only around wetlands. Breeding Bird Survey (BBS) data shows insignificant declines from 1970 to 2014 in Canada.
United States
In the United States, green herons breed north to Washington, Montana, North Dakota, Minnesota, Wisconsin, Michigan, New York, and Massachusetts. They are a summer resident and uncommon in the Northwest, scarce in the Southwest, and rare in the northern Great Plains. BBS data shows a 0.81% annual decline per year in the US from 1966 to 2015. However the North American Breeding Bird Survey (BBS) is inadequate to effectively track population trends for this secretive wetland species. Breeding populations are considered stable overall in most regions, with declines in scattered parts of the range such as the Southwest.
Mexico through Central America
The green heron is a year-round resident from Mexico through Central America. It occupies a variety of wet and aquatic habitats. Relative abundance here is not well quantified, but the species appears to be fairly common.
Caribbean
In the Caribbean, the green heron is mostly a winter visitor and passage migrant. It is considered generally uncommon in this region, though likely more common on larger islands with more wetland habitat.
South America
The green heron’s South American range extends into Colombia, Venezuela, the Guianas, Ecuador, Brazil, Peru, Bolivia, Paraguay, Uruguay, and northwestern Argentina. Here it is categorized as an uncommon species, though likely under-recorded in many areas.
Why Green Herons Can Seem Rare
While green herons have a large range and are considered common in many regions from a conservation standpoint, there are some reasons why they may subjectively seem rare to birders:
- Secretive nature – Green herons are shy, solitary birds that spend a lot of time motionless waiting to ambush prey. This makes them easy to overlook.
- Habitat – Since they inhabit wetlands, shorelines and small waterbodies, they have a very patchy distribution on the landscape.
- Breeding dispersion – They defend breeding territories, so even where present each pair needs a certain amount of space. This limits densities.
- Migration – Northern populations vacate much of the United States and southern Canada in winter.
- Identification challenge – Their mostly green plumage can make them surprisingly cryptic in vegetation by water’s edge. Beginner birders often struggle to recognize them.
Due to these reasons, seeing a green heron often creates excitement for a birder because they are not nearly as conspicuous as the more gregarious great blue heron or green-backed heron. Hearing their distinctive skeletal call or seeing them fly with neck retracted can be the highlight of a birding day.
Ideal Habitat for Green Herons
Green herons occupy a variety of wetland habitats, but are most likely to be found in certain situations:
- On wooded ponds, lakes, slow rivers – they favor areas with trees and shrubs at water’s edge to provide cover.
- Along vegetated shorelines and in wetlands with reeds, grasses and shrubs.
- Near sources of small fish such as minnows, sunfish, or shiners.
- In the vicinity of amphibian breeding areas.
- Along creeks, drainage ditches, flooded fields.
- Near rice fields and irrigation canals.
- Around wetlands with muskrat houses and beaver lodges, which they often nest on top of.
Many wetlands lack the combination of shallow, calm water and ample shoreline vegetation that green herons prefer. This further contributes to their patchy distribution.
Best Locations for Seeing Green Herons
Some of the best places in North America to spot green herons include:
Cheyenne Bottoms Preserve – Kansas
This vast 41,000 acre wetland complex hosts thousands of shorebirds and waders. Green herons nest here and can be seen stealthily stalking the shallow wetlands.
Corkscrew Swamp Sanctuary – Florida
The boardwalk trail here provides close views of alligators, wood storks, and green herons quietly hunting from cypress knees in the swamp forest.
Reelfoot Lake – Tennessee
The shallow lake margins with abundant shoreline vegetation make this a green heron hotspot. They are common sights here in spring through fall.
Horicon Marsh – Wisconsin
This shallow 32,000 acre wetland is excellent for finding green herons among the cattails, reeds and woody vegetation.
Audubon Corkscrew Swamp Sanctuary – Louisiana
This iconic swamp is home to breeding green herons. They can be seen stalking prey or returning to nests with their characteristically retracted necks.
Green Heron Nesting Behavior
One reason green herons can be challenging to find is due to their dispersed nesting behavior:
- They nest as solitary pairs, not in colonies like many heron species.
- Each nesting pair defends a territory, spacing themselves out.
- They often place nests in secluded spots in trees, on stumps in water, or on muskrat houses.
- Their platform nests are well-concealed in vegetation, not readily visible.
- They will nest singly or in loose groups, but nothing like the dense heron colonies seen with great blue herons or egrets.
This behavior means that even where green herons are common, they can be sparsely distributed across the landscape when breeding rather than condensed in obvious colonies.
Appearance and Identification
Green herons can be overlooked by beginner birders, so it helps to become familiar with their appearance:
- Small size, about 1/3 the size of a great blue heron at 13-15 inches long.
- Dark cap and back contrast with chestnut-colored neck.
- Streaked underparts in grayish green.
- Rich chestnut-colored wing plumes are distinctive in flight.
- Bright yellow legs unlike the dark legs of night-herons.
- Short dark bill unlike the longer bill of a bittern.
- Fly with neck retracted unlike great blue herons and egrets that fly with neck extended.
Learning the green heron’s appearance helps birders distinguish them from more common wading birds. Their all green color can make them surprisingly cryptic along vegetated shorelines.
Behavior and Habits
Some interesting behaviors and habits of green herons help explain why they can be tricky to find:
- Walk slowly along shorelines or perch perfectly still, waiting to ambush prey.
- Often crouch down with neck flattened to conceal themselves.
- Frequent stirring of the water draws in small fish and frogs.
- Will drop objects on the water’s surface to attract curious prey.
- Feed early in morning and again in evening when prey are active.
- Sudden short flight on rounded wings when disturbed.
- Have a wide variety of calls including a distinctive skeletal “kyow” flight call.
Their ability to stay perfectly still for prolonged periods and suddenly strike helps them hunt successfully. But it also makes them easy to overlook by casual observers.
Conclusion
In summary, the green heron is not a globally rare or threatened species, but many factors make them less than common from a birdwatcher’s perspective:
- They occupy highly specific wetland habitats.
- Each nesting pair requires a certain amount of space.
- They are solitary, dispersed nesters.
- Their cryptic green plumage provides camouflage.
- They tend to be motionless and secretive.
- Their behaviors make them easy to overlook.
So while green herons have a large range and are common in certain habitats, their evasive nature means that they always provide a special treat for birders when one is sighted. With some knowledge of their preferred habitats, appearance and habits, birdwatchers can increase their chances of observing one of these shy herons. Any fleeting glimpse or call note immediately identifies the presence of a green heron, confirming they occupy an area even if they remain hidden most of the time.