Do Great Blue Herons Migrate? Winter Movements Explained

A partial migrant

The great blue heron has one of the widest ranges of any North American wading bird, from Alaska and southern Canada to Central America and the Caribbean. Across this huge area its behavior in winter differs a great deal.

• Northern breeders east of the Rockies, in places such as the Great Lakes region, New England and the Canadian prairies, are mostly migratory.
• Southern populations, from the southern United States through Mexico, are mostly resident year-round.
• The Pacific coast population of the Pacific Northwest and British Columbia, the subspecies A. h. fannini, is largely non-migratory because coastal waters rarely freeze.

In between, many areas host both resident herons and wintering birds from farther north, so you may see herons all year without seeing the same individuals.

Why great blue herons migrate: food and ice

The main reason herons leave is not cold itself but ice. A great blue heron catches its food by wading in shallow water, so when ponds, marshes and lake edges freeze over, it can no longer reach fish and frogs. Snow also hides the voles and mice that herons hunt in fields.

Herons are surprisingly hardy. Many individuals stay through northern winters as long as some water stays open, especially on fast-flowing rivers and streams, below dams, at springs and in tidal areas. In a hard winter with long freezes, some of these birds may starve or move on late.

This is why winter heron sightings in the north are usually along moving water. A heron hunched on a riverbank in January is not lost; it is betting that the river will stay open.

Where do great blue herons spend the winter?

Herons that migrate move to areas where shallow water stays ice-free. Common wintering areas include:

• the Atlantic and Gulf coasts of the southern United States, including Florida and Texas;
• Mexico and Central America;
• the Caribbean islands;
• northern South America, mainly Colombia and Venezuela.

Herons from the same region do not all follow one narrow route. Bird banding records show that individuals can spread across a broad winter range, some stopping in the southern United States and others continuing to the tropics.

When and how they travel

In the north, most great blue herons leave between about September and November, depending on latitude and when freezing begins. They return to their colonies from late winter into spring: from about December in warm regions such as Florida and California to March in Canada, when nests are reoccupied.

Herons usually migrate alone or in small, loose groups rather than in big flocks. Like many members of the heron family, they often fly at night. With their slow, steady wingbeats and folded necks, they cover long distances without stopping very often, and they rest and feed in wetlands along the way.

Life on the wintering grounds

On their wintering grounds, great blue herons go back to their solitary habits. Each bird tends to use a favorite stretch of shoreline, marsh edge or mangrove channel and chases off other herons that come too close, especially where fish are scarce. Where prey is plentiful, for example at drying pools packed with fish, several herons may feed side by side without much conflict.

At night, wintering herons often roost together in trees or on sheltered islands. In Florida and along the Gulf Coast, migrants from the north share the same wetlands with local resident herons, which have already started nesting by the time the northern birds begin heading home in late winter.

Young herons wander after fledging

Before the real migration, many young herons go on a journey of their own. After they leave the colony in summer, juveniles disperse in many directions, sometimes even northward, looking for good feeding places away from crowded colony waters. This post-breeding dispersal is common across the heron family.

Young herons are less skilled at fishing than adults, catching only about half as many fish in their first months. Combined with migration and winter weather, this makes the first year the most dangerous time of a heron’s life; more than half of young herons die before their first birthday. To understand what they are trying to catch, see What do herons eat?

Rare visitors to Europe and beyond

Strong storms over the Atlantic occasionally carry great blue herons far off course. The species has been recorded as a rare vagrant in England, the Azores and Greenland, and also in Hawaii.

In Europe the familiar heron is the gray heron (Ardea cinerea), a close relative that fills the same role. It shows the same partial pattern: gray herons in Britain are mostly resident, while those from Scandinavia and other cold northern and eastern regions migrate, some to southern Europe and others across the Sahara to sub-Saharan Africa. For the bigger picture of why birds make these journeys, see Why do birds migrate?