With young eagles fledged at nests in Voyageurs National Park, four of the park’s 239 developed visitor use camping and houseboat sites and four undeveloped areas that were affected by temporary closures in May to protect nesting pairs are now reopened for public use.
Twenty-eight young bald eagles fledged from 24 nests within Voyageurs National Park this year. According to park biologists the following places fledged eagles: one at Crane; 16 at Kabetogama; five at Namakan; three at Rainy; two at Sand Point; and one on an interior lake. Fifty-seven per cent of all fledged young in the park in 2011 originated from 13 nests on Kabetogama Lake.
The number of young produced per occupied breeding area for the 2011 breeding population in Voyageurs National Park was 0.74.
Sixty-three per cent of breeding pairs occupying a breeding area successfully raised at least one fledgling. Breeding success of 70 percent and productivity of 1.0 are considered characteristics of a healthy bald eagle breeding populations; long-term averages for Voyageurs National Park approach these thresholds.
Nesting failures
Nesting failures occurred at 12 territories: six of nine areas on Rainy; four of eight areas on Namakan; one of 14 areas on Kabetogama; and one of three areas on Sand Point Lake.
Rainy Lake in particular experienced an unusually high proportion — 67 percent — of nest failures in 2011. By comparison, only 7 percent of nests failed on Kabetogama Lake. It is unclear why Rainy Lake experienced relatively more nest failures this year than in previous years.
VNP biologist Lee Grim said park staff will continue to monitor the Rainy Lake nests, noting that Canadian biologists reported earlier in the year that they had witnessed a lot of nesting failures on the north side of Rainy Lake during surveys.
Grim noted that for the same period of survey, Kabetogama nests showed a 90 percent success rate. Nests on the Kabetogama side of the park are pretty well protected, he said.
“We will look around areas where the failures occurred and see if there are any new nests that are found, or check to see if birds come back,” he said.
Of the six nests on Rainy that failed, Grim said the birds were incubating eggs there in the spring.
“It was a pretty cold spring, those areas over there in park on are south side of Rainy Lake and get some pretty big blows,” he said. “When you’re 70- or 80- or 90 feet in the air and there’s a big wind or a big rain storm, it’s kind of tough.”
But if weather was a factor in the Rainy Lake failures, Grim said he’s unsure.
“It’s hard to make conclusions based on four surveys a year,” he said. In recent years a graduate student spent two years watching eagle nests from a distance to see how they responded to the elements and other disturbances. “We’d get an idea of what happened if we had something going on like that,” he added.
Voyageurs National Park biologists found 74 nests within the park boundary this breeding season. Three nests observed in 2010 were gone this year either because nest trees blew down or nests fell from nest trees. One new nest was found on Kabetogama, Rainy and Sand Point Lakes for a total of three new nests.
Two non-incubating pairs were observed by nests in known breeding territories on Kabetogama and Rainy Lake. Adults were observed incubating at 36 nests compared to 33 in 2010, 38 in 2009, 30 in 2006, 26 in 2004 and 2005, and 20 pairs in 1999. Incubation occurred at one park nest on Crane Lake, one on an interior lake, 14 on Kabetogama Lake, eight on Namakan Lake, nine on Rainy Lake and three on Sandpoint Lake.
Areas reopened
Four of the park’s 239 developed visitor use camping and houseboat sites and four undeveloped areas that were affected by closures in May have been reopened. The areas were marked with closure signs and buoys.
“We appreciate the public’s assistance in protecting the bald eagles of Voyageurs National Park,” said Superintendent Mike Ward.
The four reopened developed areas are:
• Namakan Lake — Sexton Island (N 62) campsite
• Rainy Lake — Sand Bay South (R25) houseboat site.
• Kabetogama Lake — Feedem Island (K39) and Yoder Island (K 37) houseboat sites.
The four reopened undeveloped areas are:
• Kabetogama Lake — West Sphunge Island Inlet, North Wood Duck Island and West Harris Island Point.
• Rainy Lake — North Diamond Island undesignated houseboat site.
The park is obligated to follow the conservation management actions of the Bald Eagle and Golden Eagle Management Act. Each year since 1992, the park has temporarily closed the land and water areas around active bald eagle nests to visitor use during their critical nesting periods.
