Displaced: Can Wyoming's wild moose adapt?

Wednesday, January 31, 2007

By Ben Kinkade

Imagine living outside in sub-zero temperatures where food sources shrink to a bare minimum while your bones become porous and brittle as you draw strength from them. Following a river or creek downstream to shallow snow, you slip on icy areas – that previously existed only in very late winter. Wolves, mountain lions, coyotes and ravens eye you for weakness as you navigate through the frozen wilderness looking for food and safety.

But with a Mike Tyson-like temper and long, powerful legs, you survive and leave the starkness. Entering a developed valley, you cross busy highways and heavy metal objects hurtle toward you at speeds as high as 60 mph. Avoiding injury, you quickly a clear stomach-high, compacted snow bank that edges the road. As you circumvent through a network of homes and offices, you are spooked by free roaming, barking dogs. All you seek is a safe haven and available food, if it still exists.

This scenario describes what it must be like to be a Wyoming moose. The largest member of the deer family faces extreme weather, scarcity of food sources, predation, and development – all contributing to diminishing populations in the Cowboy State.
Beginning in the 1980s, local residents noticed that moose were disappearing from the Jackson Hole region. State and federal biologists, hunters and outfitters also noticed the decline. Today, as a guide in the Jackson Hole region, residents and visitors frequently ask me: “Where are the moose?”

Though there are roughly 11,066 moose in Wyoming, fewer moose are born each year and the decline is visible. Pregnancy rates have dropped from 90 percent in the 1960s to approximately 75 percent today.

Moose populated Jackson Hole in the 1880s and were added to a protected species list in Wyoming in 1882. Moose hunting licenses were sold throughout the 20th century, with 10,000 moose harvested between 1972 and 1992.

Shrinking moose populations became noticeable in the late ‘80s and early  ‘90s, and the hunting of females with calves was banned in 1998 after it became evident that calves had a higher survival rate while in the care of mom. Last year, a record low 55 moose licenses were sold due to the declining number of moose in Wyoming.

“It’s a huge loss of revenue for Wyoming,” said Doug Brimeyer, a wildlife biologist for Wyoming Game and Fish.

Moose in the Greater Yellowstone region are smaller than other types of moose, which allows them to cope more easily with neighboring elk and dry conditions. They are light colored and have a saddle pattern on their backs that helps to keep them cool in summer.

Moose need high doses of protein and minerals to grow winter coats, recover from long winters, and restore porous bones from mineral deficit during the winter. Therefore, moose prefer relatively young vegetation habitats like burned areas where plant growth is high in mineral content. Soft, fertile soil in areas with relatively-recent glacier activity also supply nutritious plants. Researcher Valerius Geist dubbed moose “fertility junkies” because of their love for young shoots, roots and leaves from plants like willows, catkins, bitterbrush and various aquatic plants. These tender, young parts have high protein and mineral consistencies.

Dr. Joel Berger, research scientist for the Wildlife Conservation Society, surveyed moose and their habitat from 1995-2004. He said, “The perspective was that moose were in trouble.” His nine-year study showed that moose are in fact declining from various pressures: scarce food supply, climate shifts, predation and human development.
Berger discovered that food resources were over-browsed. “The willows were hammered,” he said.

Berger found that available food supply and moose density were closely linked. Areas with low moose population densities had taller and more willows – one of the chief food sources for moose – than areas such as Grand Teton National Park where densities were five times higher.  Because moose and other animals cannot be hunted inside the park, willows were shorter and fewer than on adjacent Forest Service land.

Berger’s team collared 20 female moose in the Jackson Hole area each year during the nine-year study and found that pregnancy rates dropped – a sign that food supply was lacking and that the population was reaching its carrying capacity. Berger’s study also noted a decline in twinning rates – when cows produce twin calves – in the Jackson area. Mother moose can have twins in times of good forage production and selection.

Climate and weather shifts play an enormous role in the lives of animals, affecting food availability and challenging an animal’s ability to adapt. From the late 1980s through much of the 1990s, Wyoming experienced drought, which brought about an increase in ticks, according to Wyoming Game & Fish. Thousands of ticks affected moose during this time.

“[Ticks] are a severe energy drain on moose,” said Brimeyer. Moose break their guard hairs while scratching tick bites. By March, ticks are big and abundant and blood can be seen in the snow around bed sites.

“They can’t replace enough blood that’s being lost,” said Brimeyer. They become anemic and have difficulty thermal regulating during the depths of Wyoming winters.

Late winter warming, which is normal, causes deep snow surfaces to melt during the day and freeze at night, creating a “sun crust.” Sun crusts can “handicap” moose, wrote Geist. Moose fleeing through deep, crusted snow may panic and struggle. They cannot escape quickly, nor defend themselves easily. With recent and future warming trends, earlier sun crust developments could impact moose by contributing to isolation, starvation, predation and injury during escape.

Predators also play a role in moose mortality. When wolves denned in Grand Teton in 1999, half of calf mortalities were from wolves. Moose calves are also killed by grizzly bears and cougars and are killed or scavenged by black bears.

“[One of our] goals was to understand effects that predators have on moose population dynamics and behavior,” Berger said of his study.

When prey species, like moose, elk and bison, are predator-free, they may achieve abnormally high densities. For instance, from 1940-1970, moose numbers increased dramatically in the absence of wolves and grizzlies.

To compare moose reactions to predation, Berger studied moose in Alaska where moose, bears and wolves have existed together for many years and in Wyoming where wolves and bears had been depleted from the system since the ‘20s and ‘30s. Berger was able to study moose for two years before gray wolves were reintroduced to Yellowstone in late 1995, but breeding grizzly habitat had already expanded from the original Yellowstone recovery zone during his study.

Using predator scents and sounds such as grizzly feces, wolf urine, and wolf howls, Berger tested predator-experienced moose in Alaska and “naïve” moose in Wyoming. Experienced moose reacted to these associations with predators and naïve moose did not. This implies that moose in areas where predators were absent for an extended period of time will be more susceptible to predation.

From his nine-year study, Berger concluded adult female mortality was attributable to malnourishment (60 percent), bear predation (14 percent), hunting (10 percent), vehicle collision (8 percent), unknown (6 percent), and wolf predation (less than 2 percent). These results indicated that predators were not the sole reason for the moose decline.
Gary Fralick, a wildlife biologist with Wyoming Game and Fish, has noted a decline in moose population and willow communities in Sublette County and the Greys River District of the Bridger-Teton National Forest.

Fralick oversees the largest herd of moose in Wyoming, at over 70 percent of the population. In this area, grizzly and wolf predation is minimal and Fralick instead stresses the importance of unfragmented habitat for moose populations. More and more subdivisions are popping up on winter wildlife range in areas like Star Valley, disturbing critical moose habitat.

Development poses an obstacle to wildlife, as it consumes habitat and displaces animals. Game & Fish notes that more than 5,600 building permits were issued from1990-2004 in Teton County. Animals that migrate annually from higher to lower elevations or between locations have a tough time when navigating a maze of development.

Dikes and blockages on rivers change moose habitat and food availability. Development on flood plains, along streams and in sensitive areas fragments wildlife habitat, and reduces the abundance and variety of food for moose and other wildlife.

With subdivisions and development comes increased vehicle traffic, too. Game and Fish found that more than 40 moose were killed along a seven-mile stretch of Highway 390 – the Village Road – from 1990-2003. And the stats aren’t great inside Grand Teton National Park, either.

“Six moose were hit and killed by motorists within the park in 2006 and three have been killed so far this year,” according to law enforcement ranger Kevin Albright.
Most collisions with moose inside the park are attributed to speed, which can especially be a factor on narrow, winding roads.

So, besides letting nature take its course, is there anything we can do to help moose populations?

“Slow down on highways!” exclaimed Brimeyer. More moose will be moving down to lower elevations in the next couple of weeks. Keeping dogs on leashes is important as well. The rule of thumb: give moose more than 30 yards of space during the winter. If they rise, manes erect, eying you, give them space.

“It’s tough on them,” said Brimeyer, talking about the obstacles the moose face in the coming winter months.

Brimeyer said that the public can also support the Forest Service and other agencies as they manage habitat through prescribed fires, which creates new habitat and eases access issues, hopefully helping moose

Ultimately, wildlife populations are always in flux, though human actions can certainly exacerbate these changes. “The thing that people oftentimes forget is that wildlife cycle naturally with weather, access to habitat, and climate changes,” said Franz Camenzind, Jackson Hole Conservation Alliance Executive Director. These changes can sometimes actually create or provide new habitat for wildlife according to Camenzind.

Will Wyoming moose adjust to changes in climate, development and natural predators?

We’ll have to wait and see.

Photo by K. White. Wildlife Biologist Dr. Joel Berger and three moose during studies in Alaska to understand the relationship between survival and predation.

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