Jul 15, 2010


Bald Eagle expert Bud Andress

The Frontenac Stewardship Council and the Kennebec Lake Association hosted bald eagle expert Bud Andress, who began his talk at Oso Hall on July 10 with a quiz to establish some facts about these amazing birds of prey. Who knew, for instance, that the bald eagle beat out the wild turkey to become the national animal symbol of the USA; or that their primary food source is deer carrion; or that female eagles are larger than the males and both sexes take responsibility for raising their young?

Various international groups and associations, like the St. Lawrence Bald Eagle Working Group (SLBEWG), and the Canada-U.S. Lakewide Management Plan of Lake Ontario (LaMPs ) along with the Bald Eagle Platform Partnership (BEPP) and many others, are all working in their own ways to aid in the recovery of these remarkable raptors. Andress summed up the reasons for the increase in nesting pairs of birds on the shores of Lake Ontario, specifically in the 1000 Islands, saying it is largely due to the banning of the pesticide DDT in the US and Canada in the early 1970s. The ban resulted in the decrease of the DDT by-product, DDE, which was the primary cause of thin-shelled egg production by females. These affected eggs broke during the incubation period, killing the embryos within. Ten years after the DDT ban, contaminants still present in the eco-system virtually resulted in “total reproductive failure” in the species along the shores of Lake Ontario.

That all changed in the late 1980s when levels of DDE decreased by half and PCB levels dropped by 80%, allowing reproductive rates to recover steadily. In 1999 the first nesting pair of bald eagles was spotted at the Ivy Lea area on the shores of Lake Ontario, over six decades since they were last spotted there in 1937.

It is now estimated that close to 100 bald eagles are over-wintering in the 1000 Islands, and three nests have been located, which between them have produced 35 eaglets. As a result the eagles, once listed as an endangered species in Ontario, have been recently down-listed to a “species of special concern”. According to Andress, across the border in New York State the birds remain listed as “threatened” and he believes that they will “continue to be so until their populations continue to increase on the south shore of Lake Ontario.”

Mature eagles often return to nests where they were raised and Andress has been working with scientists and volunteers with the SLBEWG and LaMPs group, who are closely monitoring the three nests in the 1000 Islands.

Collecting information on the birds is of primary concern to scientists and conservations groups since their position at the top of the food chain and their sensitivity to toxic chemicals deems them as “a bio-sentinel species” and makes them “a reliable indicator of the general health of aquatic eco-systems in the Great Lakes.”

For these reasons, between 2003 and 2009 and at a cost of $74,000, a total of six fledglings from the three existing 1000 Island nests have been fixed with transmitters, which send out signals to satellites, enabling the birds to be tracked.

With the aid of slides Andress explained the procedure of processing young fledglings.

An experienced tree climber places the young into sacks and removes them from their nests, which can be 6x9 feet in size. Once on the ground each eaglet is banded and measured. Blood and feather samples are taken and a small, lightweight, backpack-like solar-powered transmitter is strapped to its back. These transmitters have a life of four years, after which time the straps naturally rot away, releasing the transmitter from the mature eagle’s back.

To date three of the six birds that have been harnessed with transmitters, named Regal, Mary and Moose, are no longer transmitting signals. The reasons remain generally unknown although Andress said that two weeks after Regal's signal was lost in January 2006 somewhere in St. Lawrence County, New York, an adult eagle was found dead at that same location. It had been shot with a .22. Mary transmitted just one single signal before hers was lost and the third's, Moose's, was last located in Lancaster, Pennsylvania.

Andress noted that a 50% success rate was anticipated before the program began and he remains hopeful that the work of the SLBEWG and LaMPs will continue to have a positive impact on the species’ continued recovery.

He listed one of their main long term goals- the establishment of 10 new nesting territories on the perimeter of Lake Ontario and the Upper St. Lawrence by 2016.

For Andress the success of the eagles’ continued recovery is a passion. “The bald eagle is a barometer of eco-system health. If they are doing well, that's an indication of how we are doing. Is this a recovery? They definitely seem to be doing well on their own and if we can help that out-even better.”

Andress recommends anyone who happens to observe any “unusual” bald eagle sightings to report them to the Ministry of Natural Resources. By “unusual” he means any nesting activity, or unusual feeding activity as well as any obvious over-wintering roost sights.

For up to date information on the location of Hal, Phyllis and Spirit, the three bald eagles who continue to transmit signals, visit the Bird Studies Canada website at www.bsc-eoc.org and click on destination eagle/eagle tracker.

 

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