Great Blue Heron Nesting (All You Need To Know)

The Blue Heron (aka. the Great Blue heron) is a large wading bird of North and Central America. This large, majestic bird can grow to a height of 138cm and has a wingspan of up 200cm!

Blue herons can make themselves at home in practically any wetlands habitat, but what about their nests?

Blue Herons’ preferred habitats range from ponds, lakes, and rivers to urban areas and artificial reservoirs. They’re flexible with their nests and will nest on both the ground and in trees at heights of 30m or more, but they will only nest on the ground if there are no land predators nearby, i.e., on islands in the middle of a body of water.

Herons construct their nests from medium to large twigs and line the interior with moss, leaves, grass, and other softer materials. If possible, herons reuse their nesting grounds for many years and maintain them carefully throughout the breeding season.

Blue herons are colonial nesters, and some of the larger colonies can feature some 500 nests or more! Heron colonies are called heronries - herons flock together close to essential feeding grounds and generally return to the same spot every year.

Read on to discover more about the nesting habits of this majestic wading bird!

Two blue heron nests

Where do Blue herons nest?

Blue herons nest as far north as Alaska and winter as far south as the northern coasts of South America. In the north, their habitats span British Columbia, Ontario, Quebec, Alberta, and Alaska.

In the south, Blue herons breed in Florida, Texas, California, and much of Central America, extending to Belize and Guatemala. Blue herons nest in practically every US state. Some populations stay all year round, whereas others migrate throughout much of Central America.

Habitat

Blue herons are highly adaptable to their wetland habitats. Overall, most colonies of Blue herons prefer untouched, pristine lakes, rivers, and mangroves located in the wilderness, but some even build their nests in urban areas. Blue herons generally prefer to nest in tall trees or platforms at the height of 30m or so. If not, they’re more than willing to nest on the ground, provided they can find an island protected from land predators.

Blue herons are pretty nonchalant regarding the presence of other birds and have been observed nesting near eagles, vultures, and various other predatory birds.

A great blue heron leaving the nest

What do Blue heron nests look like?

Blue heron nests vary and can either look bulky, strong and stable or precarious, shallow and thin, almost like a saucer. Herons often use large sticks measuring some 0.5m and above to build their nests, which results in a somewhat spiky external appearance!

Their nests are pretty large, usually measuring around 1m across, and have a central cavity that is around 30m deep.

The central cavity is typically well-structured and lined with softer and finer materials; moss, leaves, and softer foliage. Sturdy nests are usually well-maintained and developed over multiple breeding seasons. Some of the largest examples can reach 1m deep, and 2m or more across and typically weigh around 3 to 5kg.

Great blue heron nest with young chicks inside

What time of year do Blue herons nest?

Blue herons typically breed from February until May, with northern populations usually breeding later in the season. The colder the environment, the longer Blue herons will wait to breed until around May, when the breeding season begins to wind down.

Some populations of Blue herons distributed in south North American and Central America breed all year round. However, the hotter it is all year round, the more fragmented the typical spring breeding season becomes.

How do Blue herons build their nests?

When building a new nest, the Blue heron male usually transports sticks to the nest, which the female assembles. This takes between 2 days and 2 weeks, but once built, both the male and female will seek to upgrade and maintain the nest.

Herons typically return to the same breeding sites each year, but they don’t normally return to the nest they built. Instead, they’ll return to any nest at the breeding site and upgrade it throughout the season. Studies have revealed that while herons aren’t particularly bothered about whose nest they return to, they tend to stick to nests built in the same species of tree as their original nest!

Great Blue Herons (Ardea herodias) exchanging nesting material

How long do Blue herons take to build their nests?

Blue herons can build their nests quickly in as little as two days, but most take a couple of weeks to complete.

Once the initial structure is erected, Blue herons tend to keep adding to the nest throughout the breeding season. Blue heron nests are very much a work in progress, and new nests don’t look particularly sturdy the first season they’re built!

Over time, heron nests can become very large and much sturdier, expanding from some 20cm deep and 60cm across to over 1m deep and 2m across!

When do baby Blue herons leave the nest?

Baby blue herons remain in the nest for some 49 to 81 days before they fledge.

After that, they may periodically return to the nest to feed for some 2 to 3 weeks. Blue herons have a relatively slow lifecycle, and many don’t breed until they’re around 1.5 to 2 years old.

Great Blue Heron nest high in a tree containing a mother and her young

How many broods do Blue herons have?

Blue herons raise just one brood per year in the vast majority of cases.

Some Blue herons have two broods if one fails early in the season. Studies have shown that some 25% of failed nests are reused by the same pair of herons, or a different pair if they go elsewhere.

Some Blue heron pairs raise two broods a year in Central America, but this is thought to be rare.

Do Blue herons nest in the same place every year?

Once Blue herons establish heronries, migratory populations usually return to them every year, whereas non-migratory populations remain near to the colony all year round.

While researchers formerly believed that Blue herons returned to the same nests each year, it seems like they aren’t too fussed about what nest they return to at the site - on one condition - the new nest is built in the same species of tree as their original nest.

A breeding couple of blue herons. One heron is placing down a nesting stick

What do Blue heron eggs look like?

Blue herons are a pale bluish color and measure around 2 x 3in. During incubation, the eggs fade to white. They lay between 2 and 6 eggs, but three is the most common.

What month do Blue herons lay eggs?

Blue heron eggs are usually laid in their typical breeding season, which extends from March to May.

Northerly populations in colder regions breed later, whereas southern populations in Central America breed throughout the year in some cases (though still usually only raise one brood per year).

Great Blue Herons are the largest North American heron

Do Blue herons use nest boxes?

Herons aren’t too fussy about where they build their nest, so long as they’re within 2 to 5km of a waterway or fishing ground.

Conservationists support herons and other large nesting birds by building nesting platforms. These should ideally be around 5m+ in height. You can find DIY plans to build heron nesting platforms.

Where do Blue herons nest at night?

Blue herons are usually communal roosters, meaning that they’re happy to flock together and huddle at night if they’re cold. They typically form groups of around 5 to 20 birds and usually rest on the branches of tall, strong trees.

Do Blue herons nest in backyards?

If your backyard is close to a body of water, then yes, Blue herons may well nest there.

You can attract Blue herons by providing elevated nesting platforms - but bear in mind that if you have a fish pond, then the fish won't be safe for long!