Game Commission officials Wednesday announced they, along with officials from the U.S. Department of Agriculture’s Wildlife Services, have renewed a program to sustain and protect a historic nesting colony of great egrets and black-crowned night-herons - two state endangered species - on Wade Island, a three-acre isle near Harrisburg in the Susquehanna River.

This effort includes the limited culling of double-crested cormorants increasingly hoarding canopy space on this relatively unique nesting site. Culling was first used in 2006, and again in 2011.

So far, 90 cormorants have been culled from Wade Island, and there are plans to remove a few dozen more over the next few weeks. More importantly, however, great egrets and black-crowned night-herons were seen quickly making use of the recently vacated trees.

“Wade Island is home to the state’s largest nesting colony of black-crowned night-herons and great egrets, both of which are on Pennsylvania’s endangered species list,” said Dan Brauning, Game Commission Wildlife Diversity Section supervisor. “It isn’t clear what brings these colony nesting birds to Wade Island. Perhaps it is good food resources in the Susquehanna River or it’s proximity to the Chesapeake Bay. Whatever the reason, no other place in the state comes close when comparing the number of nesting sites of these magnificent birds.

“Unfortunately, double-crested cormorants - also colony nesters - have pushed their way into the night-heron and egret nesting area, and the nesting activity of the cormorants has increasingly become a concern. While cormorants were at one time rare in Pennsylvania, populations have steadily increased. In fact, populations of double-crested cormorants have been increasing rapidly in many parts of the U.S. since the mid-1970s, and their abundance has led to increased conflicts with various biological and socioeconomic resources, including recreational fisheries, other birds, vegetation, and fish hatchery and commercial aquaculture production.”

Comparing the latest survey, conducted on May 2, to the survey conducted on June 28, 2011, the number of great egret nests increased from 103 to 185, and the number of double-crested cormorant nests increased from 127 to 188. However, the number of black-crowned night-heron nests dropped from 87 to 67, during the same time period, and represents the fourth lowest number of night-heron nests in the 27 years of nest surveys on Wade Island.

Cormorants were first confirmed nesting on Wade Island in July of 1996. At that time, only a single nest was found. Since then, though, the number of cormorant nests on Wade Island has increased dramatically.

“Unfortunately, there is a limited number of nesting sites on Wade Island,” Brauning said. “This is a particular problem for great egrets, which prefer nest locations similar to those used by the cormorants. Therefore, we have initiated a culling operation by the U.S. Department of Agriculture’s Wildlife Services to remove cormorants using specialized air rifles and/or suppressed .22 caliber rifles.”

In 2006, USDA Wildlife Services removed 64 cormorants, and in 2011, the agency culled 40 cormorants.

USDA Wildlife Services has obtained all of the necessary permits from the U.S. Fish and Wildlife Service to conduct this operation under the direction of the Game Commission. The state Department of Conservation and Natural Resources owns Wade Island and has provided approval for this operation. All culled cormorants that are recovered are being turned over to the Game Commission for disposal.

Brauning noted that extreme care is taken to not disturb the endangered species nesting on the island. Culling efforts will be stopped immediately if it is perceived that activities are threatening the nesting of egrets or herons.

To ensure public safety, the Game Commission has been providing law enforcement assistance or arranging for assistance from the Pennsylvania Fish and Boat Commission throughout the operation. The equipment used is designed to reduce any risks and is used in the safest manner possible.

Brauning noted that studies have shown when nesting cormorants encroach upon colonies of other nesting birds, including both black-crowned night-herons and great egrets, they reduce the amount of nesting space for those other nesting species. In addition, cormorants have been known to take over egret nests and also kill trees as a result of their nesting activity. Several other cases found that cormorant droppings on the leaves and branches of nesting trees apparently caused egrets to abandon colonies.

Brauning stressed that culling a portion of the cormorants was not the first option explored, and has been used only twice. He noted that in 2004 and 2005, the agency attempted to encourage nesting by egrets and night-herons on neighboring islands. However, that effort was met with limited to no success.

“Trying to lure some of Wade Island’s herons and egrets to a nearby island was unsuccessful,” Brauning said. “Egret ‘decoys’ were placed on an island that neighbors Wade Island with hopes of attracting some birds away from the growing cormorant population. The use of decoys will continue, but such efforts generally provide only mixed success and may attract cormorants as well. Other methods to control the success of the cormorant nests (oiling of eggs, use of poles and high-pressure sprays) are not possible on Wade Island, because of the nest height.

“Therefore, lethal removal of the cormorants was determined to be the safest, least disruptive, most cost-efficient and promising control method.”

In support of this conclusion, USDA Wildlife Services also has considered all available management options and the adverse effects associated with those options. Wildlife Services has determined lethal control to be the most appropriate management option and does not foresee any significant negative impacts to other wildlife or the public from this option.

“The Game Commission is responsible for managing all of the Commonwealth’s wildlife species,” Brauning said. “Particular care must be taken when managing endangered species to protect them from further reduction and their possible disappearance from the state. Disturbances - or increasing competition for nest sites - can cause colony nesters to move abruptly. Wade Island is an extremely important nesting habitat for both the endangered black-crowned night-herons and great egrets, but the future use of the island by these two birds is threatened.

“While we recognize that some people will be offended by the lethal removal of cormorants on Wade Island, we believe it is the best way to ensure the continued nesting success of the great egrets and black-crowned night-herons that use this unique nesting area. In addition, the Game Commission will continue to research and look for other methods to help promote the continued existence and well-being of these two endangered species and to secure their future within our state.”

For more information, visit the Game Commission’s great egrets and black-crowned night-herons webpages.

6/18/2012