November 29, 2006
For Better or Worse, Cormorants, Pelicans Increasing on Lakes: Seldom to Never Seen on West Kentucky’s Impoundments a Few Years Ago, These Big Water Birds Are Routine Nowadays, and Big Numbers Raise the Specter of Problems.
By Steve Vantreese, The Paducah Sun, Ky.
Nov. 29--The presence of fish-eating fowl on our area's huge lakes is greatly increased nowadays.
The snaky-necked cormorants have gone from a rarity to regulars on the lakes. They are diving birds, black as adults and brownish-gray while immature, better than two feet in length with a wingspan of about four and one-half feet.
The cormorant has a yellowish bill, straight with a downward hook at the end, that it uses to seize fish that it can chase in water depths of down to 20 feet or more. Poorly waterproofed by nature (so buoyancy doesn't impair diving skills), the cormorant is often recognized at rest by its habit of sitting with its wings extended to dry its feathers. Swimming, the cormorant moves along low in the water, with mainly its longish, reptilian-like neck sticking up to be seen.
The white pelican, the largest North American water bird, has raised more than a few eyebrows on Kentucky-Barkley as a species that people more often associate with ocean coastal areas. In fact, white pelicans in interior America breed in the northern prairie pothole region and migrate southward seasonally.
This pelican is gleaming white with black primary feathers that show on outstretched wings. The bird has bright orange legs and bill (the beak that allegedly can hold more than its belly can), which develops an upright keel during the breeding season.
The white pelican is a whopper, often weighing more than 15 pounds, more than five feet in length tip to tip, and with a wingspan to nine feet.
Pelicans have become seasonal visitors in flocks that can number in the hundreds, showing up mostly from fall through early spring during migrations from northern nesting grounds.
Cormorants, too, appear in large numbers -- groups of hundreds if not more -- during fall-spring migrations, but some also are year-round residents now. There apparently are local nesting colonies where they are churning out baby cormorants that each year add to the resident flocks.
Murray State University's Dr. Steve White, an associate professor of biology, said both species of big water birds seem to be flourishing on the big lakes for a combination of reasons.
Double-crested cormorants and white pelicans both are increased continentally according to surveys, probably in large part as a recovery from the banning of DDT beginning in 1973, White said. The pesticide was blamed for depressing populations of bald eagles and other species by causing thin, weakened egg shells that virtually brought successful reproduction to a halt. Cormorants and pelicans both probably benefited from the DDT ban by a nesting success upturn.
Meanwhile, the building of major inland reservoirs like Kentucky and Barkley lakes (in the 1940s and 1960s, respectively) created new ideal habitat for both species.
"There's habitat potential now that the birds just didn't have before these reservoirs," White said. "It's better habitat than there ever was historically because man has changed the face of North America."
Related to where these birds go, conditions have changed over the past 30 or so years because of milder winters.
"We're clearly warmer than what it used to be here," White said. "And most birds will stay only as far south as they need to in order to have open (unfrozen) water in the winter."
White said another habitat factor that may have contributed to particularly the cormorant increase has been the widespread proliferation of catfish farming in the southern Mississippi River corridor.
"Cormorants find aquaculture in general and especially catfish farms to be a great feeding opportunity -- it makes great wintering habitat for them," White said. "Catfish farming and the cormorant population seem to have grown up together, and that, of course, has created an animal damage control issue."
The thus-far modest numbers of pelicans and the more seasonal nature of the big white birds on local lakes haven't raised any notable red flags in regard to the fish population just yet. There already has been some concerns stirred by the more numerous and local-nesting cormorants, however.
"Are there enough of them to represent a problem for our sport fish? Probably not, but combined with other factors, a big cormorant population is not a good thing for our fish population," said Paul Rister, the Western District fisheries biologist for the Kentucky Department of Fish and Wildlife Resources.
Rister said early concerns prompted the KDFWR to commission a cormorant food habits study here by the U.S. Department of Agriculture's Wildlife Services branch.
"The study showed that the cormorants eat mostly shad, mostly gizzard shad, and freshwater drum," Rister said. "The study of sampled cormorants' stomach contents showed that they ate a bass or two and literally one sauger, but overall they ate very few sport fish species.
"On the other hand, cormorants do feed on the same forage base, the shad, that supports game fish populations," Rister said. "I don't know if there is or will be enough cormorants out there to have an impact on the forage base, but they do compete with sport fish for the same food."
Rister said the cormorants are having a visible impact on local habitat where they have set up shop.
"They are damaging some (Kentucky Lake) islands down around Blood River and the Kentucky-Tennessee state line where they're roosting and where they've been nesting in the spring," Rister said. "They've covered up the islands, frosting the trees (with droppings) and killing trees. We've worked riprapping the islands to save them as habitat down there, and the cormorants have been killing everything on them.
"We've explored such things as noisemakers to try to run them off the islands, but that only moves them to the next island," Rister said.
While cormorants are capable of diving deep, they appear to have a preference for feeding around school of shad where the dining is concentrated and near the surface. White pelicans, meanwhile, aren't divers but rather dip their food from right at the surface. Pelicans thus also enjoy schools of shad that can be found extending to the surface for sumptuous feeding opportunities.
The near-surface, massive schools of baitfish that occur on the big sister lakes account for the mixed concentrations of cormorants and pelicans that observers often see at least fall through early spring on the reservoirs.
Pelicans aren't year-rounders to any extent so far, none being known to nest around the lakes here. But that could change.
"When you've got numbers of them coming here, from time to time you'll get a bird that's injured or for some unknown reason doesn't leave," White said. "If you ever get two that hang around like that, you can have the makings of a locally nesting population.
"If you ever get the first nest, then the birds that hatch from it tend to come back to the same area when they're mature enough to nest themselves," he said. "That's how local populations get started.
"These populations change with time, and I predict that the numbers will increase and somewhere along the way the white pelican population will begin to draw the ire of fishermen," White said. "We can take a lot more of them before they become a big factor, but some people are going to get concerned about them."
Copyright (c) 2006, The Paducah Sun, Ky.
Distributed by McClatchy-Tribune Business News.
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