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What's Bill Seeing in the Field: Opportunistic Eagles

For more than 30 years, CBF Educator and photographer Bill Portlock has been exploring, documenting, and teaching the wonders of the Chesapeake and its rivers and streams. With his vast, intimate knowledge and experience with the watershed, we thought who better to check in with about what he's seeing in the field right now . . .

Bill
On a recent spring morning, I was fortunate to be in my skiff on Cat Point Creek, a tidal tributary of the Rappahannock River in Richmond County, Virginia.

Eagle-rich Fones Cliffs, just four miles upstream from Cat Point Creek, is a unique Bald Eagle concentration zone, with thousands of eagles from Labrador to Florida as well as native Virginia birds using the area for nocturnal roosts, foraging, and (for residents) nesting. Many eagles spill over into Cat Point to forage on its abundant fish, primarily blue catfish and gizzard shad, but at this time of year there are migratory river herring and shad in the river. That the herring spring run to spawn is tied to bald eagle reproduction is yet another interwoven cycle of nature. It is a cornucopia of protein for a couple of months.

Bill1One eagle caught my attention that day by successfully capturing an alewife, a river herring just in from the ocean to spawn, in an oxbow of the creek. After the successful catch, he flew to a low branch over the water to eat his catch. Males are about 20 percent smaller than females, and when females are incubating eggs, males do most of the fishing. I allowed the ebbing tide to quietly drift me toward the scene. Today, this eagle was more focused on consuming his meal than paying attention to me.

Alewives and blueback herring are related to hickory and american shad and are members of the herring family (Clupeidae). These are anadromous fish, meaning they spend the majority of their adult lives at sea and migrate up coastal rivers in the spring to spawn in freshwater.

Bald eagles reproduce earlier than most birds in the Bay region, starting nest construction or repair in December and January. Egg laying and incubation takes place as early as December (and can run until March) in the Chesapeake Bay region. The hatching and rearing of young eagles takes place from March to June. Thus, the spawning run of herring and shad feed young eagles and the parents.

There were dozens of Wilson's snipe feeding on insect larvae, worms, and other invertebrates in the arrow arum marshes. These medium-sized shorebirds frequent the creek during winter before migrating north in April. Two pairs of blue-winged teal and a handsome pair of common mergansers were the only ducks present. But the main show on Cat Point that morning was this adult Bald Eagle capturing and eating this 12-inch river herring right in front of me.

4At one time in the not-too-distant past, coastal rivers supported thriving herring and shad industries, with millions of fish harvested each year. However, populations of these fishes declined dramatically in the last century due to dam obstructions, overharvesting, and pollution. The river herring fishery (which includes the alewife and the blueback herring) has been one of the most valuable in the Bay, with annual catches once exceeding 8 million pounds in Maryland and 30 million pounds in Virginia.

Opportunistic feeders, bald eagles also catch ducks, turtles, and small mammals (muskrat size). But fish make up the bulk of their diet, especially in warmer months. Availability of non-migratory gizzard shad and the introduced blue catfish make up the majority of prey captured now.

But on this day, a migratory alewife was the prey of this hungry eagle. Drifting slowly in my skiff to within 30 feet of the perched eagle, I was able to quietly watch and photograph the eagle. I  felt privileged to be there.   

—Photographs and Text by Bill Portlock, CBF Senior Educator

What else is Bill seeing in the field these days? Click here to see.

 

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