Featured Birds: Great Blue Herons
The Great Blue Heron, America’s largest heron, is a master at catching fish. It can hold still for many minutes waiting for a hapless fish to swim by, and then strike like lightning, spearing or snapping up the fish in a split second. Great Blue Herons don’t restrict their diet to fish: they may also become adept at catching small muskrats and other rodents, and rails, ducklings, frogs, and other small birds.
Heron feet are designed for standing on soft muddy or wet sand or soil, and their bill for spearing fairly hard-bodied fish, but they lack the tools for holding and tearing apart their prey. Instead, they swallow fish whole, first using their forward-facing eyes to determine which end of the fish is the head and which the tail. They always swallow the fish headfirst, so the fish will slide down their throat and esophagus smoothly. If a fish went down tail first, its spiny tail and rough body scales would scrape along this delicate tissue.
Herons also lack the equipment to carry fish back to the nest to feed their young, so they swallow their catch and bring it back to the nest in their own stomach. They regurgitate the food onto the nest floor for their young to eat.
Heron nestlings probably figure out that they should swallow fish headfirst when eating the fish their parents regurgitated. The adult herons’ stomach juices soften the scales, so any scraping if one goes down backward won’t be severe, but will teach the young birds to be careful.
Great Blue Herons have a long back toe that helps them to grab onto branches to sit in trees and to nest in them. They build sturdy stick nests. Most of them nest in colonies of a few to hundreds of pairs, but some Great Blue Herons are more territorial and nest far from others. No one understands why some are so much more solitary than others.
Because nests are far up in trees or snags, a young heron falling from the nest would be doomed. So baby heron legs stay bent for many days after hatching so they will stay securely in the middle of the nest. When they do start taking tentative steps after the first couple of weeks, they stay in the middle, and when they do start venturing near the edge of the nest, they hang onto the sticks very tightly.
In Florida, many herons and egrets choose nest trees in standing water where alligators are most abundant. If a chick does fall out of the nest, it will be eaten, but this happens very rarely, and the alligators protect the nest from raccoons and other predators that might otherwise swim to the nest tree, climb up, and eat all their young.
After Great Blue Heron chicks finally fledge, usually when about 10 or 11 weeks of age, they return to the nest for feedings for a few days to a few weeks more. This way they can be certain of getting good food even as they develop their skills at catching their own. The first year of life is treacherous as they learn all the tricks of surviving each season, but once they make it to their first birthday, their life expectancy goes up. At least one individual lived to be more than 24 years old.