Great blue herons are large wading birds found in wetlands across North America. They are known for their distinctive squawking call that serves several important purposes for these birds.
The great blue heron (Ardea herodias) is the largest heron in North America, standing over 4 feet tall with a wingspan of up to 6 feet. They have blue-gray feathers, long legs, and a long neck and bill that allows them to skillfully hunt for fish and other prey in shallow water environments. Great blue herons can be found year-round in wetlands, marshes, swamps, rivers, lakes, and coastal areas across much of North America.
One of the most recognizable features of the great blue heron is its loud, squawking call. This distinct vocalization serves a variety of purposes and is a key part of great blue heron communication and social behavior.
Types of Squawks
Great blue herons make a few different types of squawking calls, each with a different meaning and use:
- Alarm call – A loud, sharp “fraaank” noise that signals danger or threats.
- Chick begging call – Made by chicks in the nest to beg for food from parents.
- Contact call – A soft “keoww” used between mates or parents and young.
- Distress call – A harsh screeching noise made when stressed or threatened.
Reasons for Squawking
Here are some of the main reasons why great blue herons make their characteristic squawking sounds:
Attracting Mates
Male great blue herons make loud squawks from breeding colony sites at the start of each breeding season. This functions to attract females to potential nesting sites. The males continue squawking once females arrive to solidify pair bonds and for courtship displays.
Defending Territories
Great blue herons are territorial, especially around breeding colonies, and use squawking calls to mark and defend their territory. Loud alarm and distress calls signal trespassing to other herons and predators that may threaten nests or young.
Locating Each Other
Great blue herons nest in colonies with other pairs of the species. Squawking allows herons to locate their own nest within a busy colony site and for pairs or parents and young to regroup if separated.
Coordinate Feeding
Herons that forage together use soft contact calls to coordinate their movements and feeding. This may maximize fishing success and allow them to share information on the best feeding areas.
Begging for Food
Young herons in the nest make loud, incessant squawking and begging calls to let their parents know they are hungry. The intensity and urgency communicates how much the chicks need to be fed.
Sounding Alarm
Loud alarm squawks alert other herons to danger from predators like eagles, hawks, raccoons, or humans that may threaten eggs or chicks at the nest. This signal tells other herons to be cautious or take evasive action.
Unique Vocal Adaptations
Great blue herons have special physical adaptations to produce their wide variety of squawking calls:
- Modified Syrinx – The syrinx is the avian equivalent of the mammal larynx. Herons have an unusually well-developed syrinx with extra muscles that allow them to make diverse vocalizations.
- Long Neck – Their long necks function like a resonance chamber that allows great blue herons to amplify and project their squawks over long distances.
- Large Body Size – As the largest heron species, great blue herons have the lung capacity required to generate loud and strong squawking sounds.
When Do They Squawk?
Great blue herons squawk most frequently and loudly in the following situations:
- Breeding season from February to April
- Defending nesting territories from intruders
- Alerting to predators near colony sites
- Communicating with mates and young at nests
- Fledgling young begging for food
They are mostly quiet at night when roosting and less vocal outside of breeding seasons when not nesting in colonies.
Squawking in Flight
Great blue herons may vocalize with squawks or other calls in flight. Squawking during flight may serve to:
- Keep groups or flocks together when migrating or traveling
- Signal alarm at predators like eagles spotted from the air
- Attract other herons to feeding areas
- Defend territories from the air
Regional Dialects
Interestingly, some research indicates that great blue heron squawks have regional accents or dialects. Herons in one geographic location have calls that are slightly, but detectably, different than herons in other areas. It’s not fully clear if or how these regional vocal differences may benefit the birds.
Conservation Status
The great blue heron population declined in the early 20th century due to hunting and feather trade, but recovered and stabilized after receiving protection under the Migratory Bird Treaty Act of 1918. Their global population is estimated at around 150,000 to 500,000 birds. Great blue herons are classified as a species of Least Concern on the IUCN Red List due to their large and widespread distribution. In some regions, habitat loss remains a threat, highlighting the importance of conserving wetland areas.
Conclusion
In summary, great blue herons rely heavily on various squawking vocalizations as a core part of their communication system. Their squawks serve important functions including attracting mates, defending territories, sounding alarms, locating others, begging for food, and likely other purposes as well. The great blue heron’s large size and specialized anatomy allows it to produce loud, carryings calls adapted for its wetland environments. Understanding why these birds squawk provides insight into their behavior and the key role vocalizations play in their social structure and reproductive success.