Herons aren't really kin to pterodactyls

Great blue herons occupy nests along the Rogue River near Tou Velle State Park Thursday. More than 20 pairs of herons nest in the heronry each spring.Jamie Lusch

"Dinosaur!" the 5-year-old child of a friend exclaimed upon seeing a great blue heron for the first time. There is something primitive about the large heron, especially one in flight. The oversized wings flap deliberately as it slowly makes its way to new and distant fishing holes. They are affectionately referred to as "pterodactyls" by many birders.

Real pterodactyls, although not dinosaurs, were flying reptiles in the age of dinosaurs. They are usually portrayed as large, slow, flying animals with wings of skin stretched between elongated little fingers and the body. The face was long, reminiscent of the large bill of the heron, and the head of some was decorated with a crest.

While some species matched this image, pterodactyls were as diverse as modern birds, occupying many of the niches now filled by living birds. They ranged in size from a small sparrow to impressive flying machines with 50-foot wingspans. Some pterodactyls apparently plucked fish from the ocean like frigatebirds. Others caught flying insects like swallows. One species unearthed in Brazil had hundreds of fine teeth that were apparently used to filter plankton from the water just as flamingos use the comb-like projections inside their bill. But I digress.

Great blue herons are nothing like pterodactyls. Still, the ponderous flight that recalls the long-extinct reptiles is tremendously important to the heron. The wings appear to be oversized for the weight of the bird. Somewhat smaller wings would support them just fine and even allow them to fly faster. The large surface area of heron wings creates a lot of friction with the air and slows them down.

To better understand their need for large wings, consider the flight of a loon. Loons have ridiculously tiny wings. Tiny wings create little friction with the air, and loons do fly fast. They have to. Tiny wings create less lift, and to generate enough for flight, a loon must run as fast as it can over the surface before it has enough speed for its meager wings to haul it into the air. But living on big lakes and the ocean they can be forgiven. Space and grace are not issues.

Landing requires a similar expanse. A loon must touch down at high speeds, skidding over the surface of the water. If a loon tried to fly slowly, it would simply fall out of the sky.

Loon-like wings for a heron would never work. A heron's long toothpick legs — which permit them to wade into deep waters — are nearly as fragile as they look. A compromise, like the wings of a hawk or a goose, still wouldn't work. Even at moderate speeds, landing can be disastrous. The oversized wings permit a heron to land as soft as a feather, protecting the delicate legs. Better to get there safe than fast.

The oversized wings also help when it's time to nest. Great blue herons nest high in trees in colonies called "heronries." Landing on small limbs is an art form for all birds but especially for the heron with those stilt-like legs. Slow is good. You can see for yourself before the trees leaf out at a heronry along the Rogue River on Table Rock Road, just past the entrance to TouVelle State Park. Twenty pair or more nest high among the cottonwoods.

Stewart Janes is a biology professor at Southern Oregon University. He can be reached at janes@sou.edu.


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