Sunday, December 27, 2009

Great Blue Heron

Aggressive Sentries

I often see the herons along the shore of the Tennessee River, near Chickamauga Dam. They stand in ranks, sentry like, along the shoreline. When a hapless fish or frog passes nearby, they unleash their long beak, sharp as a javelin and fast as a striking snake. They cross the land or water with slow deliberate strokes of their powerful wings.
One year in February I witnessed aggressive competition among the herons. One flew with powerful strokes from under the railroad bridge near the dam. Another was close behind in hot pursuit, but broke off the chase as the lead heron flew past me. From the lead Heron's beak dangled the object of their dispute, a young striped bass.
I had heard of Bald Eagles pursuing Osprey until they dropped a fish. I had not thought it a common method of hunting among other predatory birds.
When the Heron landed high on the rocky shore, preparing to eat its dinner, another lifted off from sentry duty along the river and gave chase. The heron with the fish flew off toward the small marsh nearby, and dropped its fish just before it crossed above the access road. The pursuer quickly snatched the fish. It turned the tasty meal in its beak and swallowed it, headfirst and whole.
The heron that had caught and lost the fish uttered neither squawk nor hoarse croak against the slings and arrows of outrageous fortune. It merely continued on its flight toward the marsh.
On the previous day I had walked the Brainerd Levee, near the Chattanooga Airport, where I saw several herons sanding stately in the water, waiting for a fat fish or frog to pass by. When a heron flew in from the east and landed on the marsh, another left the shore near the levee and flew directly at the new arrival.
The new arrival lifted off and flew an overhead loop with the other in close pursuit. One of the birds made that hoarse croaking noise characteristic of their species, though I was never sure which one called. Soon the interloper was gone, back in the direction from which it came.
I looked at the colony of stick nests above South Chickamauga Creek and noticed that no herons stood on the nests or nearby branches. I knew this would soon change. Herons are early nesters. That evening I read that Herons defend feeding territories when they are not nesting.
The day I saw the heron with the fish, I noticed that the nests in the small marsh near the dam were occupied. Herons stood, singly or in pairs, on the nests and nearby branches that seemed barely able to support their weight. Nevertheless, the Herons would nest there. There they would hatch their eggs and feed their hungry young until the next generation was ready to stand sentry-like along the shores of rivers, lakes and marshes.

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