The great blue bird is big, beautiful and deadly.
Illustration by Robert Meganck
"Right through your eye into your brain.”
This arresting image is offered by biologist Bryan Watts, director of Virginia’s Center for Conservation Biology in Williamsburg, in answer to a question you’ve probably never thought to ask: Why should I fear the great blue heron?
You know this bird—the tall, gray-blue wader with the s-curve neck you’ll see cruising easily above a river’s surface or stalking the shallows of ponds, streams and other wetlands of the Commonwealth. Direct your attention now to its long, sharply pointed bill. For the great blue heron’s prey—mostly fish, but also a wide range of other creatures, from frogs, snakes and rodents to ducklings and other smaller birds—that bill is a rapid-strike, death-dealing weapon. A heron will sometimes snatch, and sometimes impale, its next meal, before swallowing it whole and, as often as not, still alive, wriggling, and protesting all the way down the heron’s long gullet. A heron’s esophagus can expand impressively to accommodate what it’s eating, though it is also true that, on occasion, a big meal can be a heron’s last; sometimes, they do actually choke to death.
To return to the matter of that pointy bill, though: For the unwary nature lover, who might have in mind to rescue an ill or injured great blue heron or one tangled in fishing line, “Great blue herons can be very dangerous,” says Watts. “They have an incredibly fast strike rate, and they can strike you in the face faster than you can move.”
Apparently they like to aim for the eyes. You can see—or rather you won’t see—where this is going.
Assuming you keep your distance and prevent an unanticipated lobotomy, however, the great blue heron can be appreciated as an inspiring example of one of Virginia’s ecological-comeback stories. Once devastated by DDT, great blue populations have recovered from a mere five known pairs in Virginia’s coastal plain in the 1960s to some 7,800 pairs by 2013. And the birds have been spreading west into the Piedmont and beyond as well. That “we see them all over today,” says Watts, is a case of a true recovery success.
Interestingly, the herons you see in winter might not be the same ones you’ll observe in the same place come summer. Virginia is located at a “migratory transitional latitude,” explains Watts, where at least some of “our” birds migrate south in winter while at the same time other birds migrate into the state from more northern latitudes. “It is an open question whether the birds we see in the winter are actually the same birds that are breeding here,” says Watts.
That we do see great blue herons in Virginia waters in all seasons brings up a more prosaic question—don’t their feet get cold? In human beings, frostbite to hands and feet occurs because when exposed to cold, the body shuts down blood circulation to extremities to conserve heat for the vital core organs. But the great blue heron has an adaptation called “countercurrent circulation,” says Watts. It’s a complex and remarkable heat-exchange system that keeps the legs and feet warm enough while also preventing loss of core heat, and explains why a great blue can stand patiently in icy, burbling river waters in January.
In early spring, these birds gather in nesting colonies that can host a handful of breeding pairs in a single tree, or hundreds spread across acres, according to Watts. They prefer very tall older trees like loblolly pines that have sufficient “scaffolding limbs” to support the herons’ large nests. They also prefer trees that “extend up above surrounding landscape,” says Watts, “because they are large birds with wide wingspan and they don’t fly through tight spaces well.”
As it happens, that particular kind of arboreal real estate is also preferred nesting territory for bald eagles, and in an ironic case of unexpected consequences, the success of efforts to restore Virginia’s eagle populations has resulted in some competition between the two species. An eagle family setting up housekeeping right in the heart of a great blue heron colony tends to cast a pall over the neighborhood, breaking it up. Watts says the presence of eagles is considered a possible explanation for both an increase in the number of great blue heron colonies and a small decline in the number of heron pairs found between population surveys conducted in 2003 and 2013.
Still, great blue herons seem to be thriving in the state, and this time of year is good for bird-watchers interested in observing a colony. Visit the “mapping portal” at the Center for Conservation Biology’s website (CCBBirds.org) for a guide to heron populations, then grab your binoculars and go. Just, for their sake and yours, keep in mind—best viewed from a distance.
This article originally appeared in our April 2016 issue.
