Great Blue Herons
Facts about Great Blue Herons
Great Blue Herons (Area herodias) are one of our most common, year-round resident waterbirds and as a result have become our city bird. As large birds they attract our attention and they nest in various places in or near Seattle.
Adult Great Blue Herons can stand nearly four feet tall and with a six foot wingspan appear immense in the air. They are mostly a slate-gray, with chestnut and black accents, and very long legs and neck. Adults sport a shaggy ruff at the base of their necks. Young birds are less colorful and have streaked necks.
They inhabitat both salt and freshwater throughout the state and are tied to water for their food, a variety of fish, frogs, small mammals, insects, and reptiles.
Unlike many of Washington’s heron species, Great Blue Herons do not leave our region in the winter. This is in part due to their flexible diet.
Herons are typically solitary in their feeding habits and will territorially protect their feeding grounds. In places of great abundance however, they tend to be more flexible in their spacing.
Great blue herons nest in colonies called rookeries or heronries that are established near readily available food. Their nests are typically built high in trees, near the top and are mainly constructed of sticks.
While adult birds have few natural predators, young birds have high mortality. Many larger birds and raccoons are common predators of eggs and young. In some cases herons will abandon colonies when disturbed, particularly during the early phases of nesting behavior. This has become an issue in Washington State where Bald Eagle numbers have increased, negatively impacting heronries with higher regularity.
Viewing Great Blue Herons
- Our abundance of water and their affinity for it means that throughout Washington they are common, even in areas that we typically consider dryer regions. Even in dryer Eastern Washington, they are quite common where there are rivers and lakes.
- One of the most common ways to see them is flying overhead, but they are easy to watch as they hunt because they are quite stationary, often in the open.
- They hunt along mudflats, lakes, and river and are often found standing still or slowly walking along the shore.
- Heronries should be viewed from a good distance but are a great opportunity to see a lot of unique behaviors and their young. Some urban colonies are easily accessible with the majority of activity beginning in Februrary and ending in late July.
- Typically problems with herons arise in relation to backyard water features that have fish in them. An adult heron will eat about 13 ounces of fish in a day, approximately three six-inch koi or 10 two-inch goldfish but can double this when feeding their young.
- An easy food source like a backyard pond will be visited frequently and while some may appreciate these awesome birds in their backyards, some many want to preserve their fish. Providing hiding places for fish and overhead barriers of grid netting over the water are the most effective means of deterring hungry herons.
Public Health Concerns
- Great Blue Herons do not pose any serious concerns to public health as they are not common zoonotic vectors.
- Great Blue Herons are protected under state and federal law. Only licensed wildlife specialists can facilitate their removal and only in the most extreme of circumstances.
- Several heronries exist in the Greater Seattle Area and Washington State. One of the more easily observed ones is located near on the Magnolia (south) side of the Ballard Locks in and around the Kiwanis Ravine. Other prominent rookeries can be found on Samish Island between Samish Bay and Padilla Bay (Skagit County); at the Dumas Bay Sanctuary in Tacoma (Pierce County); at Lake Sammamish State Park (in King County); on Vancouver Lake (Clark County); and at Potholes WRA (Grant County).