Friday, Jun 2, 2006
Voyageurs National Park biologists found 65 bald eagle nests within the park boundary this April while conducting aerial surveys to determine the number and location of nesting pairs. Adult pairs were observed at 29 of the nests. Twenty-eight of the 29 breeding pairs were actively involved in incubating-compared to 29 in 2005, 27 pairs in 2003 and 2004, 28 pairs in 2002 and 2001, 25 pairs in 2000 and 22 pairs in 1999.
Each year since 1992, the park has temporarily closed the land and water areas within ¼ mile of active bald eagle nests to visitor use during their critical nesting periods. The closures have been based on recommendations of bald eagle researchers from across the U.S. to land management agencies. After the young leave the nest, which usually occurs by the middle of August, these temporarily closed park areas will be reopened for public use.
This year, specific management recommendations from a two year research study on the effects of watercraft on bald eagles nesting in VNP (Wildlife Society Bulletin 2002) are being applied for the second year. Therefore watercraft users, both motorized and non-motorized, should not approach on the water within 200 yards of bald eagle nesting sites and adjacent land areas.
This summer, areas around four of the park’s 29 nesting sites occupied by breeding pairs are temporarily closed to camping and other human activities. Three of the park’s 225 developed visitor use sites are affected by the temporary closures.
The closed areas are: Kabetogama Lake -Yoder Island (K37) houseboat site; Rainy Lake-Skipper Rock Island (R45) and Sand Bay South (R25) houseboat sites. Undeveloped areas that visitors might use where active breeding pairs are nesting are also closed to human activity and marked with signs. Only one such area on Kabetogama Lake is closed at North Wood Duck Island Beach.
According to Clemson University research biologist Dr. William Bowerman, who conducts ongoing studies of bald eagles in the park, people play a very important role in protecting nesting eagles and other birds. “May and June are particularly sensitive periods for nesting eagles. Eagles may still be incubating eggs until late May, and if flushed off the nest for too long a period, the eggs will become cold and the embryo can die. Or if the adults are continuously threatened, they may abandon their nesting efforts,’’ said Dr. Bowerman.
“Once hatched, it is during the first four weeks of life that the eaglets are most vulnerable,” Bowerman explained. “During this time eaglets are unable to regulate their body temperatures and need almost constant attention from an adult to protect them from cold winds and rain, or hot sunshine.”
Natural factors can also influence eagle breeding success during critical phases of their reproductive cycle. The Shoepack Lake fire burned the nest and nest tree of an actively nesting pair on an island in Shoepack Lake in late July of 2004. The young and the adults survived the fire because it occurred late in the breeding cycle. One immature and one adult bird were perched on snags of the island that burned near the old nest site after the fire. Last season the birds built a new nest near the island that burned and an adult was observed incubating there. They are present again this year.
Individual eagles differ in temperament and tolerance to human and natural activities at different times in the reproductive cycle. Some are easily displaced by human/eagle interactions early in the cycle and may abandon a nest site, whereas others are more accustomed to close interactions with humans. Overall, reducing the adverse potential of human/eagle interactions has allowed greater nesting success of eagles throughout the United States. “Our management goal is to help ensure the continued reproductive success and recovery of this population of bald eagles, our nation’s symbol,” said Superintendent Kate Miller.
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