THE BALD EAGLES OF BESNARD LAKE
The world’s longest running study of a stable raptor population just celebrated its 50th season. Behind the research on these thriving eagles of boreal Saskatchewan.
Wreaches the rim of the bald eagle nest, the spruce needle-blanketed forest floor lies more than 20 metres below. For many, a healthy fear of heights might have kicked in around metre 10 of the climb, but white spruces are thick with branches and, says Gerrard, more or less like ladders. But it also helps that he’s done this repeatedly every July for 50 years. At 69, the longtime pediatrician, ornithologist, politician and, as of June 2017, contestant for leader of the Liberal Party of Manitoba, is still quick to scramble up the boreal giants that ring Besnard Lake, provided they’re home to one of the many bald eagle nests he and his team have located and collected data on since 1968. Staring back across this 1½-metrewide nest are two strapping eaglets, both hopping and grunting audaciously. No white-capped adults are in sight. At this time of year, the young are typically 50 to 60 days old — fully feathered and almost three-quarters of their eventual three- to six-kilogram weight, but a few weeks from fledging. Gerrard coaxes them forward, one by one, by nudging them from behind with a stick from the nest, grasps their legs above the talons and zips the birds into duffle bags, which he then lowers to the ground on climbing ropes. Within a few minutes, Elston Dzus, an AlbertaPacific Forest Industries ecologist who started coming to the lake in 1984 as a University of Saskatchewan undergrad, or other researchers and family members at ground level have banded, measured and determined the sex of the birds and sent them back up. Returned to their aerie, the siblings are annoyed but not agitated, and Gerrard bids them goodbye as he starts his descent. By the end of the field season, the group has tallied seven new nests, bringing the total to about 50 on the lake. With 32 young born in 25 of those nests, 2017 marks the highest number of successful
nests in the study’s 50 years, says Dzus, and among the top counts in terms of chick production. It’s been another good year for the world’s longest-running study of a stable raptor population.
IF YOU THINK A LAKE in boreal Saskatchewan, 370 kilometres north of Saskatoon, seems like an unlikely place for a thriving population of bald eagles, you’d be in good company. Even as the Besnard Lake study was taking shape in the late 1960s, the standard ornithological reference Birds of Canada described bald eagles as common on the Atlantic and Pacific coasts but little more than a rare and picturesque species in between. But in 1966, when Gerrard and his friend Doug Whitfield were canoeing the Saskatchewan side of the Churchill River, they “realized there were eagles up there.” Given that the pair had met while banding owls, it was only natural for them to plan a return to the area for four straight weekends the next year to find and band at least a couple of eagle nestlings. When they did, they managed to piggyback on helicopter and float plane rides with biologists and provincial wildlife conservation officers who were working in the region, and made wide, albeit cursory, surveys of parts of the Cumberland Marshes and more northerly lakes around the Manitoba boundary. “On those weekends we found 18 nests with 27 young, and we climbed up to and banded every one of them,” says Gerrard. “We were excited, starry-eyed. After that, the Canadian Wildlife Service gave us a grant to do aerial surveys, so in 1968 and ’69 we did a lot of flying in northern Saskatchewan and a bit of Manitoba.” At the end of those summers they had found almost 250 active and inactive eagle nests — including those at Besnard Lake. The news of flourishing eagle populations in central Canada’s remote boreal forest astonished the North American ornithological community, who had been watching birds of prey vanish at an alarming rate, especially from the eastern United States, due to the pesticide DDT (banned in Canada in 1970). An extensive aerial survey of northern Saskatchewan i n 1974 revealed more than 14,000 bald eagles in some 3,900 breeding areas. from southwest to northeast tip and — most importantly for eagles seeking sturdy, tall waterfront spruce, trembling aspen and pine for their immense nests — with more than 400 kilometres of shore including 250 islands, Besnard Lake was nearly saturated with eagle territories when Gerrard arrived. “We had a whole lot of questions about these boreal breeding grounds,” he says. “And Besnard was a perfect study area for many reasons. There were lots of eagles, but it was also a large lake without a town or city on it.” It’s also teeming with white sucker and cisco, the most common fish to spot thrashing in an eagle’s grasp, though they’ll also carry pike, walleye and even deep-dwelling burbot to their nests. What makes this l ake produce enough fish to sustain around 100 eagles, two fishing lodges and the owners of 70-odd cabins is its geography.