Pond and Lake Wildlife: Great Blue Herons

A call is made by a pond owner to their pond guy or Penn State Extension about a Great Blue Heron hanging around their pond. At that point, customer pond vigilance against the heron usually begins. And it should, because if the heron knows that a quick meal can be had at your pond (aka the Great Blue Sushi Bar) they will come back, and that possibility of an easy meal is when a pond owner will first see this long-legged bird hanging around their pond.

Great Blue Herons are the largest member of the heron family, approximately 38-53 inches in length, with a 70-inch wingspan. A Great Blue Heron is largely white (with a thick black stripe over the eye and feathery black crest) with dark gray underparts and grayish-blue back & wings. Great blue herons are mainly fish-eaters; however, they will eat a variety of other food items they can successfully catch. Their favorite foods include fish (up to a foot in length), water snakes, frogs, crayfish, mice, shrews, and insects such as dragonflies, grasshoppers, and aquatic insects. Individuals are generally solitary except in breeding season, although small groups may be seen foraging in an area that has an abundant food source.

Great blue herons inhabit saltwater or freshwater areas near trees suitable for nesting. They often nest in remote and inaccessible places. They may travel far (more than 10 miles in some cases) to forage and sometimes choose foraging sites close to human activity, such as urban waterways or the marshy drain field adjacent to a shopping mall. Great blue herons can nest either singly or in colonies, but usually in colonies and sometimes among the nests of other heron species.

What Problems Can Great Blue Herons Cause in a Pond or Lake?

For most pond owners their first experience with the heron is indirect, when their pond fish start to disappear in part or in whole. Typically, the heron will wade into the pond or stay pond side in a crouching position and wait patiently for a curious fish to come to investigate. These huge herons can crouch into a surprisingly small size. If the fish are small enough, the heron will continue this until there is nothing left in the pond, or it cannot physically fit anything more into its body, whichever comes first. The great blue heron knows that a quick meal can be had at your pond and will come back.

How to Keep Great Blue Herons out of your Pond or Lake

Use pond netting to create a protective barrier between your backyard fishpond and predatory birds. Ensure that the netting is taught, at a distance between 6 inches to 12 inches above the pond surface. This method is one of the most successful ways of preventing herons from eating your fish.

Remember that herons are territorial birds? A useful device that works well and is also low cost, is a great blue heron animal decoy. The theory is that herons often hunt alone and do not want to fight for their fishing spot so if they see a heron decoy near the pond, they will seek an alternative body of water. Herons are very intelligent and will catch on quickly if a decoy stays in one spot for too long so keep it moving to keep the real birds guessing. However, there is a downside to this heron deterrent; mating season may cause your plastic heron to become another heron’s cupid.

The Great Blue Heron is a majestic bird apart from its desire to eat our pond fish. It is very intelligent and capable of figuring out deterrents that are meant to scare it away. With a life span of up to 15 years, they can get lots of experience with our methods of trying to keep them away. They seem to have "routes" and will visit the same pond again and again with each visit being a learning experience about that pond. Typically, Great Blue Herons hunt in the early morning or early evening but can be seen at any time of day. The best means to keep the bird away is to use multiple methods of deterrent. Do not rely on any one form of deterrent because a heron will eventually figure them out.

This way you can get to learn how to enjoy this truly amazing, adaptable animal back in Mother Nature's waters, not yours!