From the 1940s to the early 1970s, the heron population in the valley was extremely small. They were only seen randomly. Then in the mid-1970s their numbers surged as they moved up the valley and formed new colonies, slowly and steadily like the bird itself. Clearly the leggy, wading heron had come to terms with urbanization along the rivers. Just how some species are able to adapt to life with humans when others cannot is a mystery. It suggests that each species has its own sensitivity level.
The first colony turned up in the Tennessee Valley in Meigs County at Armstrong Bend adjacent to Chickamauga Lake, according to Charles Nicholson. T. D. Pitts reported the find in 1977.
Two years later a colony was discovered at Cotton Port, also in Meigs County, followed by rookeries at Savannah Bay in 1982; Watts Bar in 1983; and Patten Island in 1984.
Between 1977 and 1988, 15 colonies appeared along the rivers in the Tennessee Valley; clearly the birds were making their way upstream. During this time the population at these new colonies jumped from 45 to 1,056.
They reached Knox County and Looney Island in 1990.
On April 12 of that year, Steve and Rebecca Satterfield were looking for the herons that had been reported along the river off Cherokee Boulevard in Sequoyah Hills, a neighborhood just west of the University of Tennessee. They scanned Looney Island with binoculars and discovered the active nest with two fairly large nestlings being fed by their lookalike parents. The late J.B. Owen, columnist for the Knoxville News Sentinel, reported the discovery and it caused quite a stir because the island was so easy for everyone to see.
Growing up in the shadow of Mount LeConte, I had never seen one of these lordly birds until life brought me to Knoxville in the early 1980s. I still recall my initial amazement on seeing one pass. “Geez,” I’d whisper under my breath.
The woodland birds I had grown up with tended to be small and fidgety, more like winged sprites, like Tinkerbell, that were here and gone before your mind had a chance to become comfortable with their presence. But not great blue herons; their deliberateness pulls them from the vaporous existence of high-strung warblers into the world of the solid and concrete.
A great blue is decidedly substantial. Watching one as it stands in knee-high water, frozen, patiently waiting for its prey, you get a true sense of the steely resolve that a master fisherman needs. You’d swear the bird to be a statue: elongated and perfect, chiseled in blue-gray marble by some modern Michelangelo. But great blue herons are real and their presence in the valley is growing.
On warm days in February, great blues begin to show up at the rookery to stake their claims. Initially, the male arrives and with feet firmly planted he will stand erect, head high. I recall one year on Looney Island, very early in the season with most sites unclaimed, a single heron stood in an uppermost nest.
In the case of the great blues, this declaration of turf marks the beginning of courtship. As with many other species, the courtship of a pair of great blue herons is elaborate and protracted. It lasts several weeks.
Even if it’s a mated pair that have produced many successful clutches, the pair bond has to be reestablished and reaffirmed.
The male and female have been living apart prior to the onset of courtship, leading solitary lives. Once they’re back together at the rookery the display behavior begins.
For the great blue herons in the valley, egg-laying probably peaks in mid-March. After that, the female and the male take turns incubating the eggs, a process that lasts about 28 days. The average clutch size is three or four. After hatching, both parents feed the young that fly for the first time in just under two months, or mid-June.
After the fledglings disperse, their parents go their separate ways until the following year.
And those once-coveted nuptial plumes are slowly shed during summer to drift away down the river unnoticed on hats no more.
