Deer Herbivory Alters Plant and Bird Species Composition

Cades Cove, located within Great Smoky Mountains National Park, is 1 of my favorite places in the world. I visited Cades Cove during June of 2017 and saw lots of deer, a few black bears, a turkey, and an herd of tame horses. It’s 1 of the best places to see wildlife east of the Mississippi. Cades Cove is known for its high density of white-tailed deer and is 1 of many areas where deer herbivory and its effect on plant species diversity and abundance has been studied. High density deer populations reduce tree regeneration and alter plant species composition and forest successional patterns. Areas where deer are abundant can also see a shift in natural communities to an alternate state, while plant species diversity becomes reduced, influencing other species of wildlife. Results of studies on the interaction between deer and plant community vary, depending upon geographical location. Some species thrive or can at least survive in high density deer locations, while these same species in a different geographical location my suffer. I’ll review some of these studies below.

Plant growth inside and outside a deer exclosure in Wisconsin.

Cades Cove, located within the Great Smoky Mountains National Park, is an area considered to have an high density of deer.

Deer in Cades Cover are not hunted, and they have little fear of people.

Look at how close these stupid asses got to this bear in Cades Cove. That bear could be mauling them in about 2 seconds.

Scientists studying the effect of deer herbivory on plant species composition use exclosures, or in other words they construct deer proof fences on certain plots to prevent deer from feeding on the plants inside the fence. They then compare plant composition and abundance inside and outside the fence. A study at the Clemson Experimental Forest found that after 2 years the difference between inside and outside exclosures was negligible. The differences aren’t noticeable until 5-20 years after the exclosure is constructed. At Callaway Gardens near Columbus, Georgia deer exclosures were in use for 20 years. Here, there were significant differences between the inside and outside of the enclosures. Inside the exclosures strawberry bush (Eunonymous americanus not to be confused with the strawberry people eat–Fragaria virginianus) and greenbriar, 2 favorite deer foods, grew taller and more dense than outside the exclosure. There was also an increase in red maple, black cherry, white oak, and sassafras inside the exclosure. Outside the exclosures there was an increase in sweetgum, wax myrtle, hop hornbeam, shining sumac, water oak, and willow oak. Black cherry benefitted from the absence of deer at this location, but at a site in northwest Pennsylvania, this species was found to be resistant to deer browsing.

Violet responds differently to deer herbivory at different locations as well. Scientists studying deer herbivory on the upper peninsula of Michigan found deer eradicated violets, but at Cades Code, though it is often eaten by deer, violet still regenerates. The scientists in Michigan identified “winners” and “losers” among plants in high density deer sites. “Winners included wind pollinated sedges and grasses in the Poa genus, along with hazelnut, blueberry, wood anemone, and wood fern. “Losers” in addition to violets were forbs such as big leaf aster, blue beard lily, strawberry, and thimbleberry. In some areas of Wisconsin deer can reduce tree sapling abundance by 90%, and they can eliminate white cedar and red oak. Oddly enough, yellow birch trees require moderate deer population densities. This species didn’t regenerate if deer populations were too low or too high.

The effects of deer herbivory were studied in a forest located in northwest Pennsylvania. The forest consisted of sugar maple, striped maple, black cherry, fire cherry, beech, and sweet birch. Tree regeneration failed in 25%-40% of clear cut plots. Species of trees that were browse resistant included beech, black cherry, striped maple, ash, and hackberry. A number of common bird species were absent from Pennsylvania forests with high deer population densities. This list includes wood peewees, cerulean warblers, yellow-billed cuckoos, and indigo buntings.

Ironically, heavy deer populations can accelerate forest successional patterns. By feeding upon pioneer species of plants, deer reduce competition for space with species that normally don’t dominate until later stages of forest succession.

References:

Thrift, J.

“Effects of White-Tailed Deer Herbivory on Forest Plant Communities”

Clemson University Thesis 2007

Wiegmann, S.; and D. Waller

“Fifty Years of Change in Northern Upland Forest Understory. Identity and Traits of “Winner” and “Loser Plant Species”

Biological Conservation 129 2006

Advertisement

Cades Cove

Most of the Great Smoky Mountains National Park is heavily wooded, and wildlife usually stays hidden in thick vegetation.  Cades Cove is 1 of the few areas in the park where tourists can reliably see wildlife because it is an open beautiful valley of fields and thin fingers of forest, resembling what many southeastern landscapes looked like until the mid-19th century.  Indians set fire to the valley annually to improve habitat for game animals, and white settlers maintained the open nature of the valley by using it as pasture and by planting row crops.  The valley remained open when the National Park Service took over the site 90 years ago.  Today, a 1-way loop road encircles the valley, making for the best accessible wildlife watching in the park.  I rode my car on the Cades Cove loop road last Saturday evening with my wife and daughter.  We saw >50 horses, 20 deer, 2 black bears, 1 squirrel, 1 turkey, and lots of crows and chimney swifts.

The herd of tame horses is located near the beginning of the loop road.  Many different breeds are represented including spotted palominos, Clydesdales, and solid black and brown horses.  I saw cowbirds foraging between the horses.  Fossil evidence shows horses did inhabit this region during the Pleistocene.  I would like to see the park service allow horses to go wild here.  Wild horses belong in North America.

There’s an herd of over 50 horses near the entrance to the Cades Cove loop road.

Black bear sightings caused several traffic jams on the loop road.  There are hundreds of signs telling tourists to pull over when they want to stop and see the wildlife, and other signs constantly warn to stay at least 50 yards away from bears and deer.  Most tourists ignore these signs.  They stop their cars in the middle of the road, rush toward the bear, and get as close as they can to photograph the bruin.  We were stuck in 1 traffic jam for 20 minutes.  At least I did get to see wild black bears for the first time in my life.  I’d rather live in a world where bears outnumber people.  It has been thousands of years since bears outnumbered the entire population of Homo sapiens on earth but before the development of agriculture they did.

We saw 20 deer.  This buck snuck behind me.

This was the only turkey I saw in Cades Cove.  I expected to see more.  While driving through the park the following day I saw an hen with 2 chicks cross the road.  Why did the turkey cross the road? 

There are 4 deer in this photo.  2 are laying down but their antlers are visible.

This was the only live squirrel I saw in Great Smoky Mountains National Park.  I was surprised I didn’t see more.

We saw 2 black bears on the Cades Cove loop road.  Look at how close these 2 stupid asses got to the bear.  They are underestimating how dangerous this situation is.  There must be at least 100 signs telling people to stay at least 50 yards away from the bears and deer.  Instead, people rush in and try to get as close as possible to take a photo.  That bear could be mauling them in about 2 seconds.

These are the rare and extirpated species that used to live in the Great Smoky Mountains National Park. Spotted skunks are rare, Indiana bats are endangered, northern flying squirrels are probably extirpated here, fox squirrels haven’t been seen for decades in the park, and northern water shrews are uncommon.

I was surprised I didn’t see more turkeys or squirrels.  The latter probably stay in the tree tops for much of the day.  I also expected to see woodchucks, rabbits, and maybe wild boars.  Woodchucks are more active in the morning, and I did see 4 of them while driving through the North Carolina mountains on the way home the following day.  I can’t explain the absence of rabbits because there is plenty of excellent habitat for them in Cades Cove.  Perhaps they were hidden in the tall grass.  Ironically, I saw a road-killed wild pig 5 miles from my house on the drive home the next day as if the wildlife watching Gods wanted to reward me with a kind of epilogue to my trip.  Despite how common wild pigs are supposed to be, this was the first road-killed specimen I’ve seen in the Augusta, Georgia area.

The National Park Service should introduce bison, elk, and cougars to Cades Cove.  I know the addition of cougars would be controversial, but the park service should be inspired to come as close to possible to establishing a complete ecosystem here.  More open areas should be created as well so that wildlife populations could increase.

The National Park Service should introduce bison and elk to this side of the park to fill up this empty space.

Bird watching at Cades Cove was not as good as in Townsend, Tennessee where our hotel was located.  I saw 5 species of birds in Cades Cove compared to 11 species in town.  However, I did encounter 1 unexpected species outside of Cades Cove but inside Great Smoky Mountains National Park.  I saw a raven while driving in the higher elevations, then saw another raven on the way to Cades Cove at a lower elevation.  This was the first time I’d ever seen live ravens in the wild.  I mistakenly thought ravens were rare here because there is only 1 raven nesting site in the entire state of Georgia.  But according to the National Park Service, the raven is a fairly common year round resident in the park.  Ravens look like humongous crows.  The birds I saw were far too large to be crows.  They were about the size of a red-shouldered hawk.  Crows are more common here, however. In addition to the 5 species of birds I saw at Cades Cove, I heard the constant song of the field sparrow.  Eastern meadowlarks are also supposed to be common here, but I didn’t see any.  I have never seen an eastern meadowlark.

Night fell by the time we left the Cades Cove loop road.  I was surprised at the abundance of lightning bugs.  Special tour buses take tourists through the park at night to see the amazing light show displayed by the synchronous firefly (Photinus carolinus) during late May and early June.  We probably saw some of the other 18 species of lightning bugs found in the park because it was too late in the season for P. carolinus. Lightning bugs are not bugs, nor are they flies.  They are beetles.  Their larva prey upon snails, slugs, and insects for a year or 2 before they transform into flying adults for the final few weeks of their lives.  Different species flash at different intervals and that is how males and females of the same species recognize each other.  Lightning bugs are only seen occasionally in Augusta, Georgia.  They are abundant in the Great Smoky Mountains because the moist forests support a large population of their favorite food–escargot.

Video from you tube of the synchronous fireflies.

Gatlinburg, Tennessee–A Tale of a Tourist Trap Nightmare

I’m taking a break this week from my usual essays about Pleistocene Georgia to write a travelogue of a vacation my family forced upon me.  For my daughter’s 15th birthday my wife promised her a trip to Gatlinburg, Tennessee, a crowded tourist trap, bordering the north end of the Great Smoky Mountains National Park, which is itself an overhyped haven for wildlife.

Gatlinburg, Tennessee

The sidewalks are jammed with tourists from early morning till midnight, and they come from all over the world, including Ohio, Louisiana, Iowa, Florida, Texas, Missouri, Japan, and Germany.  Little shops and stores, like cigars crammed inside a tin can, stand in line on both sides of the confusing winding streets, beckoning the tourists to throw money their way.  There’s a Ben and Jerry’s Ice Cream Store, a Guinness Book of World Records Museum, a wax museum, a celebrity car museum, a hat and cowboy boot outlet, a country western bar, pancake houses and barbecue restaurants, a McDonalds, and untold other high, low, and middle end stores.  All this exists but with precious little parking.   There are no alleys in between the stores and no parking lots in front or to the sides of the businesses.  We found a parking lot in back of one museum that cost us $10.  My wife is disabled and I didn’t want to have to wheel her chair across town.  Gatlinburg’s not that big–I recommend (if tourist traps are your cup of tea) to hike downtown from your motel, or you can take one of the trolleys.  The streets are interspersed with rights of way for walking tourists, but out-of-town motorists don’t realize this, creating a dangerous hazard.  Other motorists disregarded the pedestrian rights of way, until they saw me stopping.

My daughter chose to throw our money away at the Ripley’s Believe it or Not Museum.

Ripley’s Believe It or Not Museum

I found this freak show rather lame and outdated, but I guess it’s ok for kids.  There’s nothing here surprising to a person well versed in science and history.

This is a hairball from a pig.  The poor animal must have coughed its lungs up to get this out.

This is a photo of me next to a replica of Robert Wadlow, the tallest man to ever live.  In a boxing match between us it would’ve been hard for me to land punches above the belt.

This poster of spiderman is made out of real spider webs.  Amazing!

This is a medieval chastity belt.  I bet men found a way to overcome this.  Where there’s a will, there’s a way.

Mark Gelbart Eats an Eyeball–Believe it…or Not

We ate supper one night at the Smoky Mountain Trout House, an overpriced tourist trap restaurant.  They serve trout 13 different ways.  The sides were nothing special–frozen crinkle cut french fries, the driest hushpuppies I ever ate, and bottled salad dressing.  The trout was good–I wolfed down a whole crispy fried one.  This was the first time I’d ever eaten a fish with the head left on.  I made Andrew Zimmern of the Travel Channel series Bizarre Foods proud when I dared to eat a fish’s eyeball.  It tasted strong, much fishier than the flesh, and I could feel the solid texture of the lens on my tongue.  I didn’t eat the other eyeball and don’t recommend eating them, unless starvation is imminent.

We ate lunch at the Flying Pig Smokehouse.  The prices here were more family friendly, and the barbecue genuine.  The apple cinnamon barbecue sauce went well with smoky pork.

Great Smoky Mountains National Park

I highly recommend this park for those interested in botany.  Situated as it is in the middle of eastern North America and with varying elevations, plant species diversity is high.  There are plants that prefer warm climate growing next to species with cold climate affinities, much like what grew further south in Georgia during the Ice Age.  I found hemlock, white pine, loblolly pine, white oak, chestnut oak, northern red oak, beech, birch, elm, tulip, red maple, box elder, buckeye, sweetgum, sycamore, hickory, bigleaf magnolia, and black walnut.  The large numbers of black walnut within the park boundaries surprised me.  This tree’s wood is prized by furniture makers.  It’s rare outside the park, though it formerly was a common species of our eastern deciduous forest.  Rhodadendron was common in the understory.

This is the view from Newfound Gap.  The mountains are literally smoking.

Meigs Falls

Rhodadendron in the center of the photo.

This is a potential bear den next to the Appalachian trail.  When large mature trees fall, the roots rip up caverns, making it easy for bears and other critters to dig deeper tunnels.  This part of the trail was busy and noisy.  We were sandwiched between a motorcycle convention in the parking lot and a hiker playing loud music.

I do not recommend Great Smoky Mountains National Park for tourists interested in wildlife viewing.  By far the most common large mammal species in the park is Homo sapiens–the park is badly overcrowded.  The main highway #441 that bisects the park has bumper-to-bumper traffic.  I even got stuck in a traffic jam.  Supposedly, the park holds 6,000 white tail deer, 1600 black bear, 600 wild boar, and 100 elk.  The only mammals I saw were an estimated 40,000 people and one gray squirrel–a bitter disappointment.  Supposedly, 200 species of birds reside in the park.  I saw 5, and they were species commonly seen in Augusta, Georgia where I live.

95% of the park is a closed canopy forest; the balance is meadow.  Some of the forested area is old growth.  Large mammal populations are low in old growth forests, and what little lives there is hidden in the trees.  No timbering is allowed so mast-producing trees, such as oaks,  are being shaded out by less productive trees.  Coupled with the loss of the chestnuts to the blight in the last century, this means there is little food available for large mammals.  Moreover, most of the areas in the park that are favorable for wildlife viewing were closed. Cades Cove, Roaring Fork, and Clingman’s Dome were all closed either for maintenance or due to rock slides.  Cataloochee Valley, on the eastern side of the park where the elk were re-introduced, is remote and difficult to access.  It’s at the end of a long, winding, unpaved road that’s steep and has a speed limit of 5 mph.  Because my wife’s disabled, I was nervous about continuing on this road.  If our car broke down, it would’ve been a disaster because she couldn’t walk back to civilization.  So I turned back.

I didn’t even see any interesting small mammals.  Red squirrels, also known as chickarees, inhabit the park as well as chipmunks and woodchucks.  None of these species live near Augusta, but alas I didn’t see them here either.

I did see lots of butterflies, especially eastern tiger swallowtails.  Their larvae feed on many of the tree species so common here.  I also saw two different kinds of butterflies from the Pieridae family.

The museum at the park welcome center had many fine stuffed specimens.  The museum affords about the only opportunity for a visitor ot see animals in the park.

I did catch a whiff of a nearby skunk at Newfound Gap.  It didn’t smell as bad as our hotel room which I nicknamed the Armpit Motel.

This is a tulip tree trunk.  Large, mature tulip trees are a dominant tree in the park.  None I saw approached this is circumference.  Most people don’t realize that much of the original forest in this area was leveled by 1910.   The forest now consists of second growth.

This is the biggest bald faced hornets next I’ve ever seen.  They’re a marvel of insect engineering.

Supposedly, this is a trout stream.  The waters are clear but I saw no fish, turtles, frogs, or fish-eating birds.  Don’t expect to catch trout here.  The only trout left in the area are grown on fish farms.

Admittedly, I’m a cynic.  I suspected the park administration exaggerated mammal population estimates to encourage tourism.  So to prove to myself that animals actually live in the park, I looked for tourist videos of wildlife in the park on youtube as evidence that they weren’t just making these figures up.   I don’t have direct links but do a search at www.youtube.com for “Bear breaks into car at Clingman’s Dome,” “Cades Cove black bear,” and “Elk in the Cataloochee Valley.”  Note how incredibly ignorant some of the tourists act around bears.  The footage of bears tearing up logs while looking for termites, and another of one digging up a yellow jacket nest is interesting.  The video of a bull elk bugling, while the rest of the herd rests behind a flock of turkeys is the kind of scene I had hoped to see.

Overall, I think the park is poorly managed and underfunded.  The current ratio of closed canopy forest to meadow limits quality wildlife habitat and viewing.  Selective tree cutting, as practiced by native Americans, would improve both.  Bison, wild horses, cougars, and wolves should be re-introduced.