The brown bears living near Malaspina Glacier in Southeast Alaska's Wrangell St. Elias National Park are a unique breed of bruin. They live in a constantly changing landscape, eat an unusual diet and have developed a one-of-a-kind genetic structure. Recently, the bears were the subject of a four-year study, part of a larger effort to help give Alaska Department of Fish and Game resource managers adequate information to help develop management strategies for bears in that region.
But regional Fish and Game biologist Anthony Crupi said the study also points to "the potential implications of changing climate conditions on bear-salmon ecosystems" as Malaspina Glacier is subject to environmental variations like glacial movements, changes in the area's streams due to movement and runoff, and climate change.
Over the course of the study, Fish and Game captured 18 brown bears living near Malaspina Glacier and equipped them with GPS radio collars. They studied the bears' movement patterns and size of their home range, which ultimately shows how far a bear will travel.
After collecting more than 64,000 locations visited by the brown bears, biologists determined that a male Malaspina Glacier brown bear's home range of 178 square miles is two and a half times larger than a female's home range of 71 square miles.
"Malaspina brown bear home ranges were among the largest of salmon-dependent bears, potentially the result of dispersed salmon spawning streams with inadequate fishing locations, leading to increased movements necessary to track the morphological variation of spawning salmon," said Crupi.
Currently, the region's sockeye, pink and coho salmon, which Crupi describes as among the "strongest runs in the world," are key ingredients of the brown bear diet.
But as the glacier recedes, Crupi expects stream habitats available to spawning salmon will change. As salmon occupy and spawn in those re-routed and newly created habitats, Crupi expects that bear movements will also change in order to sustain their diets.
Crupi used Glacier Bay National Park, also in Southeast Alaska, as a prime example of stream succession following glacier recession. "Vegetation began to grow after 30 years, and salmon colonization ensued after 40 years," said Crupi.
The research and data collected from 2009 to 2013 also indicated a rather unusual, but prominent, ingredient of the brown bears' diet in that region: strawberries.
From mid-July to mid-September, while an abundance of wild strawberries were blooming and ripening in the area around the glacier, the bears moved the most.
"They're avoiding ice and snow and have concentrated their activity along the shoreline. But what is really interesting is the beach environment that they use, and through some of our resource selection models we found they are heavily reliant on herbaceous habitat," said Crupi, adding that grass and strawberries are mostly what is found in the bears' scat during the summer months.
He later explained in an email that some bears do munch on domesticated strawberries from human gardens, but he knows of no other bear population eating wild strawberries in the abundance that the Malaspina brown bears do.
Crupi describes the bears living on the beaches near the glacier as "relatively healthy." There is a low mortality rate and adequate evidence of reproduction. But he also believes that their population exists at a low density and individual bears add less mass in the summer months than bears residing across Yakutat Bay, on the Yakutat Forelands, where a similar study took place.
The bears are also isolated from human predators and other bear populations by 30 kilometers -- or about 19 miles -- of saltwater and ice, which has kept them separated from other Southeast Alaska bears long enough to give them a genetic structure different than any other bear living in the region.
"Because of that remote location, there is very little genetic inflow," said Crupi.
Crupi told the story of bear 722, which was captured near the Yakutat landfill and collared in 2010. The bear spent the fall foraging, but the following spring swam in the 33-degree water from Latouche Point to the Malaspina Forelands, across Yakutat Bay -- a distance of about 3 miles.
"It is very unusual for them to swim that far," said Crupi.
Bear 722 spent just over two months near Malaspina Glacier before swimming back across. Biologists found him dead from an unknown cause shortly after he returned to Yakutat. Crupi said there is no sign that he successfully mated with a bear at the glacier, and because their genes are so different, Crupi said, there would have been obvious signs.
Malaspina Glacier is shrinking, but not in the way that many think of. In the last 125 years, USGS research geologist Bruce Molnia, estimates the glacier has only lost about 5 percent of its area. Where it's quickly losing ice is in its volume because its actually thinning.
Malaspina is a unique type of glacier. It is scientifically referred to as a "piedmont glacier," which is the result of a steep valley glacier spilling into flat plains. The Alaska Department of Fish and Game calls it "the largest piedmont glacier in the world."
"If you look at the perimeter, it is covered by glacier reduced sediment," said Molnia. According to Molnia at some places, the glacier is supporting vegetation which he said acts as an insulator and slows the rate of melting.
In some areas, Molnia said, the glacier is thinning at least 6 feet a year.
But despite its loss of volume, Crupi said he expects the Malaspina brown bears to maintain their isolated location and their unique genetic structure.
"I believe that the expanse of the Hubbard Glacier, between Yakutat and the Malaspina, will continue to isolate bears demographically as well as genetically," said Crupi.
Crupi's findings will be published later this month. He added that future studies could explore the "impacts of climate change, particularly projected variation in temperature and snowfall, on spawning habitat as well as brown bear denning chronology."