Episode 13
Copyright © John Page Williams Jr. All rights reserved.
This is John Page Williams reading from "The Chesapeake Almanac." The month is June and the title is "The Stalkers: The Great Blue Heron and Their Kin."
The great blue heron is one of the Chesapeake's best-loved birds. People who live on the Bay's rivers, creeks, and coves talk of "our herons" who fish the shores outside living room or kitchen windows. Many a cruising family has spent a happy hour at anchor in the Wye River or the Corrotoman watching a solitary great blue stalking the edge of the marsh. Canoeists feel their spines tingle as they round a bend in a stream to see one of the big birds taking flight with a squawk. Great blue herons are stirring sights at any time. There are large numbers of them in this region, and many stay year-round unless driven south by winter ice.
The great blue stands 50 inches tall, with a wing span of 70 inches. The species is widely distributed, breeding in spring from coast to coast across Canada and from there south and east to South Carolina and Bermuda. The birds winter from the northern United States down into Central America. The Chesapeake is in the overlap between the breeding and winter ranges.
The great blue heron's bill is a most lethal device. Six-and-ahalf inches long, sharp and strong, it ranks up there with the osprey's talons and the angler's hook for tonnage of fish caught on the Chesapeake each year. The osprey has powerful wings and good distance vision to go with its talons, a superb combination for catching fish on the surface of open waters. The angler has a rod and reel, and often a boat and a depth-sounder, for catching fish on the Bay bottom.
The great blue heron is at least as well equipped. That bill is attached to a long neck which can be curled to strike like a snake. To guide its lightning like dart, the bird has excellent close-range binocular vision with keen distance judgment. Four-toed feet six to eight inches long allow the animal to walk on almost any sort of river bottom from hard sand to soft muck, as well as on dense beds of underwater grasses. Long legs allow it to hunt in water up to 18 inches deep and give it a high vantage point for locating prey. The bird coils its long neck, stands motionless, peers into the water, and then strikes quickly and powerfully. There is no predator on the Chesapeake better designed for catching fish in shallow water.
The Chesapeake provides lots of habitat for herons. The main-stem, tidal tributaries, and small feeder streams have over 8,000 miles of shoreline. Most of it offers water less than two feet deep, and some areas like Tangier Sound and the flats at the mouth of the Poquoson River have broad expanses of shallow water. Even the fresh and low-salinity portions of the tidal rivers, which normally have deep waters on the outsides of their sweeping meander curves, build large marshes with extensive flats on the insides of those curves.
These edges are rich, fueled by thousands of acres of fresh, brackish, or tidal marshes, and, when the Bay is healthy, thousands of acres of submerged grasses. The shallows are havens for all the small creatures that make up the heron's diet. In low-salinity waters of the Bay system, these include banded killifish, shiners, and young pickerel. In higher salinity waters, they include mummichogs, striped killifish, silversides, bay anchovies, and juvenile menhaden. The birds feed also on crayfish, small crabs, frogs, young snakes, mice, and even grasshoppers. Like most widely distributed animals, they are opportunists.
The fact that the fish they catch are small works in the herons' favor: they are best equipped to handle prey under six inches long (though they do occasionally take larger food), and what the fish in the shallows give away in size, they more than make up for in numbers and overall tonnage. So the herons have a great deal of food available to them.
In the air, the heron's flight is slow (about 30 miles an hour) and deliberate, with the neck coiled up for balance and the long legs trailing behind. The coiled neck has an interesting feature. In most birds, such a curve would collapse the trachea (the windpipe). The herons and their kin have S-shaped joints that allow their tracheae to be folded without collapsing. The joints are visible when the birds are wading or roosting.
The heron's large wings provide great lift. The bird may glide for short distances, but most of the time the wing-beat is steady. Apparently this system allows those herons that migrate to make their long trips successfully. It also gives them great maneuverability. They are particularly impressive coming into or taking off from the tall trees in which they often roost. They are adept at breaking their flight and can climb almost vertically from one limb to another in the same tree.
Great blue herons change their habits in February and March to travel to their rookeries. Relatively tolerant of people during the rest of the year, they retire until early summer to a few well-isolated locations where they congregate in large numbers. This is the nesting season, and only unmated or subadult birds remain in their usual haunts. The rookeries are always places with mature, tall forests, generally pines or tulip poplars, and they always offer the birds privacy. A number of the rookeries, each with 15 to 200 nests, are on the islands that stretch down the Eastern Shore, from Poplar Island in Talbot County, Maryland, to Watts Island in Accomack County, Virginia. There are also a number of rookeries in the wooded, upper tidal sections of the western shore's big rivers.
The largest rookery on the Bay, in fact, with over 700 nests, is at the head of one arm of Nanjemoy Creek, on the Potomac in Charles County, Maryland, just above the Route 301 bridge at Morgantown. There are indications that great blues come from considerable distances outside the Bay region to join local herons here. The Maryland Chapter of The Nature Conservancy deserves a great deal of credit for preserving this invaluable piece of heron habitat.
Great blues are relatively quiet most of the year, but their rookeries are noisy with the cries of both young and old. Nests are platforms in trees, 30 feet or more off the ground. Occasionally a young bird falls out of the nest, to get caught in a tree branch or drop to the ground. Either way, it is left to die and rot. The results of such accidents, added to decaying scraps of fish left around the nests, give these places a characteristic stench.
A rookery may seem to be a chaos of loud squawks and unpleasant smells, often surrounded by poison ivy and thorny green-brier. But somehow, out of it all come beautiful, graceful birds that disperse around the Chesapeake and to points beyond. We are fortunate to have so many of them here.
In fact, we are more than fortunate. The Chesapeake has enough habitat for stalkers that it supports eight other species of heron besides the great blue, though most of them are warm weather residents, and they include the great egret, the snowy egret, the cattle egret, the little green heron, the little blue heron, the Louisiana heron, the black-crowned night heron, and the yellow-crowned night heron.
Of these "others," the egrets are the most obvious. They are pure white. The great egret is nearly as large as the great blue, with black legs and a yellow bill. It is more a bird of open marsh country and higher salinities than the great blue, though there are exceptions, especially in spring and fall. (All three egrets winter south of the Chesapeake, so at times of migration, large numbers of them move through our region.)
The snowy egret is much smaller than the great egret and is distinguished by a black bill and bright yellow feet. In Victorian times, it was hunted nearly to extinction so that its white plumes could grace ladies' hats. Protection since the first part of this century has brought it back. The snowy occasionally forages in the wash along open beaches.
The cattle egret is a recent arrival, having spread across the Atlantic from Africa to Brazil and then up through Central America. This species, as its name implies, tends to stay with large herds of cattle, eating insects and field seeds. It is often seen around farms on the rivers, like Wye Plantation on Maryland's Eastern Shore.
The little green heron is the smallest of the group and has the shortest legs. It perches on fallen trees and other shoreline objects, stalking or waiting as appropriate, then making a lightning strike with its lethal bill. This strategy actually gives it an advantage over the others, because by relying on perches like tree limbs, it can fish deeper water than others can reach by wading. Due to its dependence on trees and the like, it prefers rivers and creeks. After the great blue, it is probably the Chesapeake's most widespread heron, but because of its size, it is usually unnoticed by humans. It's a beautiful bird and a delight to watch.
The little blue and the Louisiana herons (the Louisiana, I should note, is occasionally known as the tri-color) they frequent the marshes of the lower Bay. They and the yellow-crowned night heron are the least common in the area, but they are well worth keeping an eye out for. The little blue, as its name implies, is half the size of a great blue, and is colored a deep cerulean sky blue, in keeping with its Latin name. The Louisiana is easily recognizable for its very slender build and its white breast under a slate-blue body. The two night herons are, as the name implies, most active from dusk till dawn. They are stockier than the others and again, are primarily birds of the open marshes and hammocks of trees.
A point worth noting about the Bay's herons is that while their niches (or lifestyles) are basically the same, they are not exactly the same. This diversity allows all nine species to coexist while minimizing direct competition. The diversity lets them as a group take maximum advantage of all the stalking niches that the Chesapeake offers.
Thus we have a rich community of herons here. If there is any threat to them, it is their need for isolated, protected, mature woodlands for breeding. Like the great blue, the others all require trees for their nests, and in a few stands, all nine species nest together, sorting themselves out by height of nest from the ground. Disturbance from humans drives them away, so protection of heronries is an important part of land conservation efforts. We all owe a debt of gratitude to the private and government landowners who have heron rookeries and protect them. A Bay without its stalkers would be a poor place.
For more happenings around the Bay in June see our other Chesapeake Almanac podcasts and read our blog post "Worms in Love in June."
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