Great blue herons are such a familiar sight in summer that a lake, pond or waterway seems bereft without its own long-legged stalker along the shore.
North America's largest heron stands about 4 feet tall, and its 6-foot wingspan can suggest an eagle in flight. But wait — this bird has long legs trailing behind it, and a long neck tucked into an "S" shape as it swoops down to land on the edge of the water, not eagle characteristics.
They're migratory birds, and the first great blues returned to our area right on schedule this year, with several sightings reported on St. Patrick's Day. These early birds were ready to take a chance on finding open water along shoreline edges for stalking fish.
The rest of the birds followed in fits and starts. By early April, a group of six great blues was spotted huddled in adjacent trees at the Bass Ponds in the Minnesota Valley National Wildlife Refuge in Bloomington. The birds' body language, with backs to the wind and heads tucked, spoke volumes about our wintry spring weather.
We think of these big wading birds as laid-back and languid, because they're most often observed standing motionless along a shoreline. Or we see them meticulously stalking prey, lifting one long leg after the other in slow, deliberate steps.
But this approach is the genius of the heron family — they're extremely patient birds, often waiting for prey to come to them. (Think of the black-crowned night-heron, not moving a muscle for hours as it perches on a branch over the water.) Masters of stillness, herons often engage in long periods of inactivity, burning few calories as they stand and wait. And this lack of motion often helps confuse prey: When a great blue roots itself to a spot in the water, small fish may mistake its two long legs for reeds, failing to recognize the danger they pose.
They're highly successful predators, switching from stillness to lethal hunting mode in the flash of an eye, with a lightning-fast strike of that long neck and sharp beak when prey comes into range.
It's startling to think of great blue herons as carnivores, but of course they are, with a diet dominated by fish and frogs and the occasional small mammal. These herons also consume crayfish, small turtles, salamanders, snakes, dragonflies, grasshoppers and even smaller birds. Everything goes down the bird's gullet whole before passing to the stomach, where strong acids break down all but the most indigestible bits, even fish bones.
