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Wednesday, 21 March 2007 00:00

Ice age relics

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Chris Kelly didn’t seem fazed by the frigid February temperatures as she rock-hopped an icy stream and plunged down a trail into the Middle Prong Wilderness for another daily adventure into the world of flying squirrels.

 

Specifically, Kelly’s mission was tracking the endangered Carolina Northern Flying Squirrel. There’re 950 flying squirrel nest boxes tacked up to trees throughout the Southern Appalachians. It’s Kelly’s job to check each box one time during the winter field season.

It’s a hit or miss affair — mostly miss. Last year only 50 boxes out of the 950 she checked had squirrels burrowed in them. The boxes emulate hollow tree cavities the flying squirrels normally nest in.

The Carolina Northern Flying Squirrel is a tricky critter to catch. For starters, there’s not many of them. The endangered species is sequestered to high-elevation mountaintops where spruce-fir forests grow. Both the squirrels and forests are remnants of the last ice age. They moved higher and higher up the mountain in search of the last vestiges of a cold climate and are now trapped there.

There’s only eight high-elevation pockets across the Southern Appalachians where the flying squirrels live, mostly in Western North Carolina but there are also a couple in East Tennessee.

“The spruce-fir habitat this animal is tied to is restricted to the extreme high mountain top islands,” said Kelly, a biologist with the N.C. Wildlife Resources Commission. “It is so isolated by miles and miles from other suitable patches of habitat they can’t intermix. They can’t disperse from the Great Balsams to the Black Mountains, from Grandfather to Roan Mountain.”

If global warming plays out like scientists predict, the flying squirrels could be pushed off the top of the mountain as their high-elevation islands warm up.

“The spruce trees like it cold and the flying squirrel lives in a cold microclimate, so exactly how that’s going to impact them, we’re not really sure,” Kelly said.

The North Carolina Wildlife Resources Commission is currently revamping its Wildlife Action Plan to reflect the impacts of global warming on various species.

“We are thinking about it, and we are trying to figure out what might happen,” said Jeff Schwierjohann, also a biologist with the N.C. Wildlife Resources Commission.

In the meantime, there are plenty of other threats to the flying squirrel: second-home growth, logging, road building, acid rain, and recreation. Anything that potentially alters the spruce-fir forests can hurt the flying squirrel. That’s one reason the biologists study these squirrels — it’s not just the endangered squirrels they care about, but the forest they inhabit.

“It’s what that species says about the habitat and what’s going on with the ecosystem,” Schwierjohann said. “Most people in North Carolina will never see a Carolina Northern Flying Squirrel. It’s not that big of a deal to them. But the habitat and what it means for our streams is very, very important.”

 

Strike one

For today at least, our mission was to get lucky and see some flying squirrels. Kelly corralled the group of visitors along for the expedition and gave us our marching orders. When we reached the site of a nesting box, Kelly would venture off the trail first. She would creep up on the box and plug its exit hole to keep the flying squirrels from escaping. Then she’d give us the signal to move in.

Kelly is the latest biologist to carry the torch in the flying squirrel survey — now in its 11th year.

“We know a little more than we used to,” Kelly said. “It is something we pick away at slowly. We could really get into it with a lot more money and a lot more time.”

When Kelly catches a flying squirrel, she puts it through the paces of a physical exam similar to what it would get at the vet’s office: weight, measurements, gender check. They also get a nifty piercing on the ear, complete with a serial number.

“If we catch them again, we’ll know who it was and when we caught it. Over time if we catch that individual again we can get an idea of population size and trend,” Kelly said.

It was unpleasantly cold, but winter is when the flying squirrels are more likely to be in their nests, burrowed down inside a mass of shredded bark and leaves.

“This is a very cold hardy animal, but they also like to snuggle up and stay warm,” Kelly said. “The flying squirrel nest traps warm air, like down fibers in a coat, and is an incredibly warm little place for them to cuddle up.”

The same squirrels will make nests in a host of boxes and tree trunks in their territory, taking up residence in which ever one strikes their fancy that day.

“They use many, many den sites,” Kelly said. “That’s why we have so much trouble tracking populations.”

Kelly then took a sharp turn off the trail and disappeared behind a rhododendron patch. We waited dutifully for the signal, but Kelly reappeared momentarily holding the splintered remnants of a box, possibly mauled by a black bear. This was a first, Kelly said. The nest boxes do wear out and need replacing, but mostly due to the elements.

The flying squirrels have predators, namely owls and other birds of prey. They know every tree hole, escape route and hiding place in their territory, which can be up to 70 acres. The squirrels are nocturnal and venture out for food mostly at night. Their favorite delicacy is truffles, but they eat all sorts of mushrooms, nuts and insects — when they can get to them.

“This time of year if you came out here and this was covered with a foot of snow, you’d kind of wonder what they can eat,” Kelly said. “But you’ll notice all these trees are encrusted with lichen. Some of the lichens contain oils and other nutrients.”

 

Foiled again

We hit the trail again in search of the next box. Remembering where 950 boxes are from one winter to the next isn’t feasible, so she consulted the directions handed down by previous biologists on the project. Still, it’s not that easy.

“It’ll say ‘45 meters from box five in a small birch opening in a rhododendron thicket upslope 20 meters’ and tell you to turn at a stump next to a spruce tree,” Kelly said.

Not too intuitive in a forest full of spruce trees, so Kelly counts her steps to mark off the meters between boxes.

“It all depends on your stride length and how in shape you are,” Kelly said. “I calibrated my stride length 10 years ago. Usually I’m fairly on.”

Soon Kelly had veered off into the woods once more. Too anxious to wait for her “all clear” call, the group quietly began picking their way through the forest in Kelly’s direction until we were clustered around the tree with her. This box seemed to be a good candidate. The sides of the box are wood, but the bottom is made of chicken wire. One glance from below tells you whether there’s a nest inside or not.

Kelly propped her thin aluminum ladder against the tree, bounced on the bottom rung to tamp it down and climbed about 10 feet up to the box. Her first move was to jam a leather glove in the entrance hole to keep any sleeping squirrels from clamoring out before her net was in place to catch them.

She passed a rope around the tree and clipped it to her climbing harness. Now it was show time. She removed the leather glove and fit a net bag over the opening. She whacked on the side of the box with her other hand, creating such a racket anyone inside would surely be rousted out. But nothing did.

Kelly moved onto step two: poking a shiskabob skewer through the chicken wire in the bottom of the box to rattle the nest and prompt the stubborn squirrels to flee — hopefully right into her bag. But again, nothing. A few more whacks on the outside of the box for good measure, and Kelly concluded this nest was empty.

Sometimes all that work results in a bag full of squirrels, but the wrong kind. The Southern flying squirrel — a non-endangered flying squirrel — will also take up residence in the boxes. The Southern flying squirrel is a more common species, the kind that gets in your attic, Kelly said. They live at lower elevations, but will venture up the slopes into the spruce-fir forests of the Northern Carolina flying squirrel and snag a box knowing a good nest when they see one.

 

Eureka

Sometimes Kelly spend days at a time in the blistering cold scaling trees and whacking boxes with only a few squirrels to show for it. But she didn’t seem daunted. At the next box, Kelly repeated the routine. This time a flying squirrel came shooting out and landed in the net. A few more whacks produced another squirrel, then another.

“Bag o’squirrels,” observed Chris North, a wildlife advocate with the N.C. Wildlife Federation.

“Squirrels in-coming,” Kelly said, handing the bag down the ladder.

Once back on the ground, Kelly set up a make-shift processing station: clipboard, scales, calipers, a log to sit on and a handful of white cloth bags. She transferred each squirrel from the net into their own baggies. She nestled two of the bags down in her backpack and kept one out to work up.

“We put them in a place where there’s no wind and no chance they will get stepped on,” Kelly said. “If it’s a really, really cold day and we have several squirrels to work up, we put the squirrels in our jacket so they can stay warm.”

None of the squirrels had tags in their ears, a good sign.

“You are looking at the ratio of animals that you are catching that are marked previously versus animals that aren’t marked. It gives you an idea there are more out there,” Kelly said.

Each flying squirrel was poked and prodded for about 10 minutes in what seemed like a terribly traumatic predicament for them. The stress apparently doesn’t have lasting impacts. One tagged female was caught five years in a row — a year longer than the average life expectancy for flying squirrels. The recurring trauma of being caught didn’t appear to cut her life short.

With the ear tags secure, it was time to release the squirrels. The group gathered around the base of the tree where they were captured. Kelly took one bag at a time and shook the squirrel out onto the trunk.

Flying squirrels, or more accurately gliding squirrels, are equipped with a thin flap of skin that runs from their wrist to their ankle. The skin flap looked like a furry cape as the squirrels scurried up the tree.

“Their tails are flattened kind of like a rudder. It doesn’t actually help them steer, it just helps them with braking when they are landing and it helps them with balance.”

When the reached the top, they posed for a moment and then leapt into the air. Their wings stretched out like magnificent hang gliders and they soared swiftly out of sight down the side of the mountain.

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