ADFG Fish and Game biologist Thomas McDonough and Jeff Selinger prepare to collar a tranquilized moose in February 2012

Learning after the burn: Fish and Game to study moose population

The Funny River wildfire burned nearly 200,000 acres, transforming the ecology of a large portion of the northern Kenai Peninisula. Researchers from the Alaska Department of Fish and Game have planned a study of how this new ecology will affect the behavior of one particular local species — moose.

Post-wildfire ecosystems are generally favorable to moose. According to the Fish and Game publication Moose News, experts credit the increased frequency of wildfires caused by human settlement in Alaska for a rise in the Kenai’s moose population in the earlier part of the 20th century. Dan Thompson, a wildlife biologist from the Alaska Department of Fish and Game, said that Kenai’s moose thrived in the aftermath of previous wildfires.

“What happened in the recent history of the Kenai is that in 1947, then again in 1969, there were two large wildfires” on the northern Kenai Peninsula, said Thompson, “In the 15 to 20 years after those fires, because of all the forage that became available, moose numbers increased.”

The forage that Thompson spoke of consists of hardwood trees such aspen, birch, and willow, as well as shrubs such as fireweed, roses, and elderberry. These trees and shrubs are more prevalent and accessible in post-fire ecosystems.

“In areas that haven’t burned, the willows, birch, and aspen have grown out of the reach of the moose, or large enough that moose can’t break them over,” said Thompson. “Also, as the forest matures, a lot of the understory species — like fireweed and roses — start to decline because the canopy is becoming more closed and not as much light is coming down. When you have a fire coming through, those areas re-sprout in the years afterwards with a lot of things the moose consume during the summer. You also have the trees, birch, aspen and willows, either sprout or reseed back in, and then you have available winter browse at a level the moose can utilize. As those areas become mature stands of trees, less forage is available, and as a result the moose population has been in steady decline since then.”

Moose News estimated that the Kenai’s moose population peaked around 1971, and speculates that human suppression of wildfires, which decreased the frequency of moose habitat renewal, might be a factor in the population’s decline.

For a moose, the tall, old spruce forest that dominated the fire area before the burn would have been an unappetizing landscape. Spruce is not edible by moose, and its shade prevents the growth of more moose-nutritious shrubs. However, this shade is also a necessary part of a moose’s life.

“Moose are a very large animal. Being that way, they are very good at conserving internal heat,” said Thompson. “That’s why at very cold temperatures, they aren’t affected. The downside of that is that if it’s hot, they can’t get rid of that heat fast enough, and they might go into a heat-stress situation.”

When this happens, a moose must cool itself in a bog or shaded area.

“The spruce forest offers them cover,” said Fish and Game Program Coordinator Sue Rodman. “But to eat, they need things that grow outside of that.”

Because they require both young, open forest and old, shaded forest, the Funny River fire may have been especially favorable for moose.

“The 195,000 acres within the fire’s perimeter didn’t all burn completely,” said Rodman. “If you fly over it, you see that there’s lots of places that were too moist to carry fire.”

The lower-lying regions in the burn area, as well as those near streams, were better preserved because of their greater concentration of moisture. Clusters of moist-wooded birch and aspen also burnt less easily than the naturally dry black spruce that composed large swaths of the forest. This patchwork of burnt areas and preserved areas created a landscape pattern that foresters call a “mosaic,” which provides the juxtaposition of varied forest types that moose need.

The particular circumstances of the Funny River fire created other variables that could affect vegetation regrowth and the resulting moose behavior. Because the Funny River fire occurred in May, “there was still frost under the soil, only a few inches down,” said Rodman. “That means that the fire couldn’t burn really deep. It didn’t necessarily burn through the organic layers of the soil to expose the mineral soil underneath. That mineral soil is the seedbed for hard woods to grow in.”

Rodman speculated that as a result, the post-fire ecosystem might be less friendly to moose-edible hardwoods than to Calamagrostis, a grass that forms a minor part of moose diet and might out-compete young hardwoods for ecosystem resources.

“(The Funny River fire) wasn’t as hot as the other two fires (in 1947 and 1969),” said Thompson. “One of the things we’re going to look at is how it burned, and how the moose will respond.”

To study the specific effects of the Funny River Fire, Fish and Game biologists have designed a study to precisely observe the behavior of moose in the post-fire landscape.

“The Alaska Department of Fish and Game submitted a proposal to the Legislature last year to help fund moose habitat enhancement,” Rodman said. “It was approved. Then, because we had this opportunity after the Funny River fire, we decided to put some of those dollars into collaring moose so we could find out their response to this fire.”

Researchers from Fish and Game will attach collars to moose that will allow them to be tracked by GPS. Thompson said that 25 moose will be collared and monitored from the beginning of winter 2014, until January 2017, when the moose collars are programmed to automatically drop off.

Because heat control is a strong factor in moose behavior, the study will correlate the moose’s movements with their temperature via internal thermometers implanted in each collared moose. According to Thompson, the thermometers will allow researchers to study “how moose use the landscape in relation to thermal regulation.” This data will be used to understand more precisely what spacing of open and shaded land is best suited for moose.

Rodman said that a better understanding of moose habitat has practical as well as scientific value. The portion of the legislative money not spent on collaring will fund the other half of Fish and Game’s moose project: using the data from the collar-tracking study to manage moose habitat in the future. Rodman is leading this effort.

“The other dollars … will go to on-the-ground mechanical treatments to actually cut down spruce trees to help regenerate new young trees,” Rodman said. According to Rodman, the proposed cutting will serve the interest of both humans and moose by accomplishing two goals at once.

“I’m talking specifically about mitigating for wildland fire and enhancing the habitat for moose,” she said. “The site prescriptions you’d use to do both of those things is effectively the same.”

These two objectives fit together because the trees that make good wildfire fuel — dry spruces — also make poor moose food, while the trees that are good moose food — moist-wooded willows, aspens, and birches — burn poorly. Thus a forested area made into good moose habitat also becomes a good firebreak. Rodman wants to create stands of forest that serve both purposes.

“We can make them far enough off the primary road system that they would also be good moose habitat — not near a road where vehicle collisions occur,” said Rodman. “That makes sense with fire mitigation too, because you want to put fuel breaks around a community, between the fuel and the homes.”

“If we are able to do some of these mechanical treatments over the next few years to secure fuel breaks around the communities, then in the future if there are wildland fire events that occur out in that fuel zone, in the contiguous forested areas, maybe we could let them burn a little bit longer, because now we’ve got a buffer area around our communities.”

Fish and Game is currently delaying their deployment of the GPS collars due to this season’s unusually warm weather. Thompson said that moose are easier to locate from helicopters when the ground is covered in snow. Colder weather also prevents a pursued moose from overheating. According to Thompson, Fish and Game biologists will put the collaring project into action as soon as the weather is favorable.

 

Reach Ben Boettger at ben.boettger@peninsulaclarion.com.

ADGG Fish and Game biologist Thomas McDonough with a collared moose in March 2014.

ADFG Fish and Game biologist Thomas McDonough and physiologist John Crouse attach a radio collar to a moose in March 2012.

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