A foul fowl on Swift Creek Reservoir
Double-crested cormorants, loon-like birds with an insatiable appetite for fish, have taken a liking to a small island in Swift Creek Reservoir and along a small section of shoreline in the Woodlake community.
Fortunately, the birds are not nesting there. For now, they are just roosting during the non-breeding season.
“They weren’t really a problem until this past spring when the numbers got up to over 400 to 500. They are very gregarious . . .,” said David Faulkner, Woodlake resident and Woodlake Community board member.
Faulkner said the birds initially roosted high in the trees on an island near the Hull Street entrance to Woodlake. As the population grew, the cormorants expanded to trees along the shoreline near the Woodlake Condominiums.
“The adult birds eat a pound a fish a day,” explained Faulkner. While most fishermen may abhor the birds because of their voracious appetite, Woodlake residents and other lakeside residents are more concerned about the aftermath of eating that much fish – the excessive excrement that is produced by 400 cormorants.
The trees on the island still bear signs of the roosting cormorants. Many branches are bare either from the excessive guano or from the birds’ habit of pruning leaves from the trees.
“We don’t want our trees killed,” Faulkner added. “We don’t want the acidic waste which can damage boats and the docks and help break them down more quickly. And it also stinks. It’s really bad odor.”
The guano not only kills the trees, but it can adversely affect other wildlife that would naturally inhabit the trees or island. Furthermore, if the trees and other plant life die on the island and nearby shoreline, the result could mean more erosion and siltation for the lake.
“Animal and Plant Health Inspection Service [APHIS], an agency of the United States Department of Agriculture, thinks that these [cormorants] came to us probably from a colony down on the James River close to Hopewell,” Faulkner explained. They believe the birds “recruit and bring in others” from other sites.
Cormorants have been observed feeding on the lake in past years, but their population was small.
“According to a report I got from the water authority back in the spring, they were telling me that they’ve had cormorants on the reservoir for years, smaller populations that were moving about the lake,” said David Allaben, district supervisor and wildlife biologist with APHIS. “I’m not sure why they chose that island, but it looks like a pretty good spot to me.”
While there are no other cormorant roosts in Chesterfield that are causing a similar problem, Allaben said there are two known nesting sites in Virginia, one on the James River near Hopewell and one in the Chesapeake Bay.
According to Allaben, cormorants could always be found along the eastern United States. But their numbers plummeted between the 1950s and the 1970s due to DDT, a pesticide used to control agricultural pests.
The DDT accumulated in the fish that the cormorants ate. The more fish they ate, the more the DDT accumulated in the cormorants. The chemical didn’t kill the birds, but it made their eggshells so thin that they cracked during incubation.
A ban on DDT in the mid-1970s, enactment of state and federal laws that protected the birds and abundant food supplies helped the cormorant population to rebound.
This fall, the adult and juvenile birds will probably return to the island and Swift Creek Reservoir. APHIS will be ready.
“We have plans to basically wait until the birds start to come in. We don’t want them all to get here,” said Allaben. “But when we have enough to make it worth our while, we are going back in there and probably do three- to five-nights-worth of dispersal where we’ll have three boats on the lake with our employees on each boat. They will be patrolling the lake making sure they [the birds] don’t move to another portion of the lake.”
A combination of lasers and noise (pyrotechnics) will be employed to scare the birds off the island and the nearby shoreline.
“The intent of the dispersal will be to try to drive them back to big, natural areas where they can do their thing and not be in conflict with humans and human resources and values such as our trees and our boats and dock. Their wastes are very acidic and can be very damaging,” said Faulkner.
A trial was conducted on Sept. 12 on a small flock of juvenile cormorants roosting on the island. After the first salvo of lasers and pyrotechnics, the birds promptly dispersed. Later, smaller groups of the birds returned cautiously to the island. Another round was issued, and the birds left for good.
Late October or early November will be the real test. Once the cold weather grips the Great Lakes, flocks of cormorants will migrate south. For some, their winter retreat could be the island and shorelines of Woodlake.
Meanwhile, Faulkner and Allaben will be eyeing the horizon awaiting the flocks of cormorants that may descend on the lake.
The double-crested cormorant
The double-crested cormorant is a large, aquatic bird about 31 inches in length and with a wingspan of 54 inches. The birds weigh about 4 to 6 pounds.
Its common name describes the two tufts of feathers that appear on the heads of adult birds during the breeding season. The scientific name, Phalacrocorax auritus, translates into “eared sea crow.”
The adult birds are black, have a long neck and a long, slender bill with a hooked tip. They have a noticeable orange throat patch and have large, black webbed feet that propel them underwater when they hunt for fish. Juvenile birds are the same size, but have a gray or gray-white plumage on their necks and bellies.
In the eastern United States, cormorants are vilified for the amount of fish they consume and because their nest and roosting sites cause environmental and property damage.
In contrast, some Asian cultures revere the bird as a pet, setting up pens for them to live in and using the birds to catch fish. They collar the bird and secure it with a leash. When fishing, the cormorants swallow the smaller fish, but not the larger ones because of the collar. The fishermen haul in the birds and disgorge the larger fish which they keep for their catch.