Squirrels and Blue Jays vs Acorn Tannins

For over 10,000 years acorns were the most important source of food for Native Americans wherever oak trees were common.  Acorns are an important source of food for animals too for everything from mice to bison.  However, acorns contain tannins, a substance difficult to digest and even toxic for some animals.  For example horses that eat too many acorns may die. Oak trees rely on animals to spread their seed, but if too much of their seed is consumed, their populations will decline.  The nutritional value in acorns attracts hungry animals, but the tannins act as a semi-deterrent.  Acorns from species in the white oak family evolved a different strategy for coping with acorn predation than species in the red oak family.  White oak acorns contain less tannins and are more palatable, so squirrels and jays prefer these and spread them throughout the landscape, but they germinate as soon as they are buried in the fall.  When a squirrel or jay tries to retrieve them later, it is too late.  White oaks only lose acorns that are consumed immediately.  Acorns from oaks in the red oak family are high in tannins, but the tannins are concentrated in the bottom half of the acorn.  Squirrels gnaw on the top half and abandon the bottom half.  If enough of the bottom half is left, the acorn can still germinate, though red oak acorns don’t need to germinate until spring because squirrels and other animals don’t want to eat the part of the acorn with such an high concentration of tannins. This year the sand laurel oaks (Quercus hemispherica), the most common oak species in my neighborhood, are producing a bumper crop of acorns, and the squirrels are gnawing the tops of them but leaving the bottoms.

Squirrels eat the tops of acorns from oak trees in the red oak family.  These acorns, found in my backyard, are from a sand laurel oak. also known as Darlington oak.  The top part of acorns have less tannins which are hard for most animals to digest.  Nevertheless, squirrels risk death from the 8 cats that live in my backyard to exploit this food source.  Oaks can germinate from acorns with the tops gnawed off.

Squirrels fed a diet of just red oak acorns in an experiment ate less.  Blue jays fed a diet of red oak acorns in an experiment actually lost weight.  Squirrels living in a location with mostly red oaks must vary their diet with other foods such as white oak acorns, nuts, fungi, berries, and insects.  Blue jays fed a diet of red oak acorns and acorn weevil larva maintained their weight, showing how blue jays can survive in the wild on a diet of mostly red oak acorns because the infestation rates of acorns by weevil larva are high.  Incidentally, oak trees were able to quickly colonize New England and southern Canada following deglaciation at the end of the Ice Age because of the acorns that were spread by blue jays.

Tannins posed an obstacle for hungry Native Americans as well.  According to Euell Gibbons, Native Americans processed the acorns by boiling them in water to leech out the tannins.  It’s necessary to periodically change the water–a tedious process.  I tried this years ago with the sand laurel oak acorns in my yard.  After dumping the water out and replacing it 8 times, I got tired of the process and gave up.  The acorns were becoming less bitter, but still not palatable enough to eat in a satisfying quantity.  Native Americans with no modern day supermarkets were most persistent from necessity.

References:

Chang-Macoubrey, A;  A.E. Hagerman, and R. L. Kirkpatrick

“Effects of Tannins on Digestion and Detoxification Activity in Gray Squirrel (Sciurus carolinensis)”

Physiological Zoology 20 (3) 1997

Johnson, W., Libby Thomas, and Curtis Adkinson

“Dietary Circumvention of Acorn Tannins by Blue Jays: Implications for Oak Demography”

Oecologia 99 (2) 1993

 

 

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Pleistocene Blue Jays (Cyanocitta cristata)

When I was attending 3rd grade during the 1970/1971 school year, Perry Harvey came home with me everyday after school.  On occasion he could be reckless.  One unfortunate day he swung a baseball bat at an oak tree, and the bat rebounded, struck him in the head, and knocked him out cold; taking the old cliché “knock yourself out” to a literal reality.  Another day he made the mistake of picking up a baby blue jay that had fallen out of its nest.  Every blue jay in the neighborhood screeched and dive-bombed us.  He put the blue jay down, and the birds chased us into the house in a scene reminiscent of the Alfred Hitchcock classic The Birds. Like some other species of birds, blue jays practice communal defense.

YouTube video of a blue jay attacking a gardener.

Blue jays are intelligent birds from the corvid family which also includes crows and magpies.  They are well adapted for living in the temperate deciduous woods of eastern North America and have probably occupied that habitat for many millions of years.  However, I have been unable to find any studies of blue jay genetics, and I don’t know how long they have existed as a distinct species.  It seems likely they diverged from the common ancestor of the gray, Florida scrub, and Stellar’s jays before the beginning of the Pliocene over 5 million years ago.  Fossil remains of blue jays dating to the Pleistocene have been found at 3 sites in Florida, 1 site in Georgia, 1 site in Alabama, 1 site in Tennessee, and 3 sites in Virginia.

Blue jays played an important role in the spread of oak, beech, and chestnut trees north following the ends of Ice Ages.  Nuts and acorns are a major part of a blue jay’s diet, and they often carry excess food to distant locations where they hide them for later use.  A scientific study concluded blue jays were the sole reason oaks, beech, and chestnut were able to colonize deglaciated territory so rapidly after the end of the last Ice Age.  Squirrels invariably bury acorns and nuts so near the roots of the parent tree that they could not have been the agent of dispersal.  But blue jays carry nuts as much as an half a mile away.  Without blue jays there would be no oak or beech trees in eastern Canada and northern New England today.

Reference:

Johnson and Webb

“The Role of Blue Jays (Cyanocitta cristata) in the Post Glacial Dispersal of Fagaceous Trees in Eastern North America”

Journal of Biogeography 16 1989

The Red Bat (Lasiurus borealis)–Another Pleistocene Survivor

When I was about 10 years old, I woke up one night and heard something flying around my bedroom.  The creature kept clumsily hitting the walls and from the sound of leathery wings smacking into plaster I knew it was a bat and not a bird.  I walked down the hall to my parents bedroom.

“There’s a bat in my bedroom,” I told my mom.

My mom’s not a girly type of woman who freaks out at the sight of a bug, so her reaction really surprised me.  She later told me she thought I was dreaming, and she did not expect to actually see a bat.  But as soon as she turned on the hall light, a big bat, looking just like a prop from a vampire movie, came flying straight toward us.  My mom slammed her bedroom door in my face, and I ducked under the bat which proceeded to fly down the stairs.  A few minutes later, my mom opened the bedroom door a crack and told me to round up my sisters.  She wanted us to sleep in her room that night because she was afraid the bat might carry rabies.

My mom refused to cook breakfast the next morning.  We went to eat at IHOP instead.  My dad owned a private medical practice at the time, and  one of his patients was in the pest control business, so my dad sent him to our house to look for the bat.  He did examine the living room curtain, but evidentally didn’t see the roosting bat.  That night, we watched a war movie on television, and the explosions from World War II artillery awoke the bat.  The bat crawled down the curtain and started flying around the room.  My dad grabbed his tennis racquet, I opened the front door, and he backhanded the bat out the doorway.

Big brown bat (Eptesicus fuscus).  I believe this is the species that startled my mom into slamming her door in my face.

Based on my memory of its wingspan, I believe the bat that invaded our home on Hogarth Avenue in Niles, Ohio circa 1972 was a big brown bat.  They commonly crawl down chimneys and get inside houses.

There are  9 species of bats that range into Georgia today.  During the Pleistocene there were at least an additional 2 species.  The extinct Pleistocene vampire bat (Desmodus stocki) must have lived in what’s now Georgia then.  And prior to the Last Glacial Maximum, Brazilian free-tailed bats (Tadadira brasiliensis) probably lived here as well, but this species has yet to recolonize its former range, since the climate has warmed following the end of the Ice Age.  Fossils dating to ~40,000 BP of this species have been excavated from Mammoth Cave, Kentucky which is far outside its present day range.  Fossil evidence of bats in Georgia is limited to cave dwelling species–gray myotises (Myotis grisescens), big brown bats, and pipistrelles (Pipistrellus subflavus).  The latter species has a wingspan of only 3 inches–a pipsqueak–and can be confused with a large moth when viewed from a distance.  There are several interesting species of bats that roost in Georgia’s forests, and therefore are not as likely as cave dwelling species to be represented in the fossil record.  Rafinesque’s big-eared bat (Plecotus rafinesquii) roosts in hollow cypress trees, and yellow bats (Lasiurus intermedia) exclusively spend days hidden in Spanish moss.  Perhaps the bat best adapted to the climatic fluctuations of the Pleistocene is the still abundant red bat.

The Red Bat (Lasiurus borealis), still extant, is well adapted to climatic fluctuations and is a real survivor of the Pleistocene when climate fluctuations were drastic compared to those of the most recent 11,000 years. 

Unlike most bats, this species is covered in fur and has short ears.  It’s capable of surviving at lower temperatures than any other species of bat, though it does become inactive below 68 degrees F.  They migrate south during the winter but spread as far north as Canada during the summer. They can also hibernate, if necessary.  They roost in trees, shrubs, and even within leaf litter on the ground.  They become active 90 minutes after sunset when they begin hunting for moths (26% of their diet), flies, mosquitoes, crickets, bugs, beetles, and cicadas.  They use echolocation to catch flying insects on the wing and to pounce on crawling arthropods.  Most species of bats give birth to 1 or 2 young, but red bats have litters as large as 5.  The mother bats leave the baby bats at the roost while foraging.  They will transport them to new roosts, however.  7% of the red bat population carries the rabies virus.  A predator such as a house cat or possum could easily become infected, if they find a red bat in the leaf litter.  Surprisingly though, blue jays are the top predator of red bats, mostly attacking the young.

Red bats have been excavated from fossil sites in Missouri, West Virginia, Virginia, Florida, and even Bermuda.  Apparently, a red bat washed up on a Bermuda beach 400,000 years ago and became fossilized.  Red bats are an ancient species and will probably survive the scourge of white nose syndrome, the disease that is wiping out all cave dwelling bats in eastern North America.  Because red bats are a solitary forest dwelling species, they are less likely to become infected with the communicable disease.  They’ll still be with us when, sadly, most other species of North America’s eastern bats are probably going to become extinct–an ecological disaster.

Tornado Damage at Black Rock Mountain State Park

A greater variety of trees grow in the southern Appalachians than in any other region of the United States.  The temperate forests in North America are more diverse than those of Europe because the mountains run from north to south instead of east to west.  The ranges of European trees couldn’t retreat south when Ice Ages began–the Alps blocked their way.  Late in the Pliocene many plant species disappeared from northern Europe, never to return there.  But in North America, plant species ranges were able to expand and contract in correlation with the retreat and advance of glaciers.

I visited Black Rock Mountain State Park near Clayton, Georgia on my vacation last week and enjoyed seeing the diversity of trees.  I found white oak, black oak, red oak, sycamore, sweetgum, river or sugar birch?, elm, shagbark hickory, black walnut saplings (no mature trees), tulip, locust (Gleditsia sp.?), red maple, southern sugar maple, hemlock, white pine, Virginia pine, and shortleaf pine.  I also found a single chestnut but couldn’t locate the tree it came from.  It’s likely from a sprout that will eventually succomb to the blight.  The forests in north Georgia differ greatly from what I saw in the Great Smoky Mountains National Park last year (see “Gatlinburg Tennessee: Tale of a Tourist Trap Nightmare”).  I barely saw any oaks in that park, but I noticed in north Georgia that white oak is one of the most common trees from Hiawassee to Clayton and black and red oak are abundant as well.  The forests in north Georgia must be younger than those around the Great Smoky Mountains National Park.  Oaks are fire tolerant/shade intolerant.  Tulip and maple shade out oaks in old growth forests.  The National Park trees are also much larger in diameter.  In north Georgia I couldn’t find a single tree greater than 3 feet in diameter.  Black Rock Mountain State Park was purchased from private landowners in 1939, so the forest here is only 72 years old.  I prefer the younger oak forest over old growth tulip and maple forests because they support more game.

View from Black Rock Mountain

White oak in Black Rock Mountain State Park.  White oaks are one of the most common trees in northeast Georgia but are declining in much of their former range in the midwest.

White oaks are declining in abundance throughout much of their range due to fire suppression.  In the midwest maples are replacing them, and oaks can’t grow in their shade.  Fire destroys maple trees and opens up the forest canopy for oaks.

I didn’t see any bird species in north Georgia that I don’t normally encounter in Augusta.  However, blue jays were very abundant–they go hand-in-hand with white oak forests.  Some scientists believe it was blue jays that helped facilitate the return of oak forests to the midwest and New England following the retreat of the Laurentide glacier at the end of the last Ice Age.  In the region about 100-200 miles south of the ice sheet, oaks persisted in small thermal refuges alongside rivers, but these oak woodland relics were surrounded by boreal forests and prairies.  Blue jays carried acorns for miles, storing them for future use in hidden caches.  Acorns never retrieved sprouted in sunny meadows and dying spruce forests that were failing due to a warming climate.

A tornado wrecked this tree.

When a tornado felled this tree, the roots ripped a big cavern into the earth.  This would make an excellent bear den with a fallen tree as a natural roof.  The bear might dig making it a  little deeper.  Bears are unlikely to use this one though because it’s next to a trail.

Earlier this summer, a tornado destroyed many of the trees on Black Rock Mountain.  Roofers were repairing all the houses bordering the park.

Many different kinds of flowers abound in sunny areas of the southern Appalachians.  This one looks like some type of aster but I’m not sure.  Maybe somebody can help me out with the ID.  I also saw orchids, field daisies, and many I couldn’t identify.

A chipmunk hole?  I saw a chipmunk not too far from this hole.  The park provides perfect habitat for chipmunks.  They like to tunnel under tree roots and boulders, and there are lots of acorns.  This is 1 of 2 species of mammals I observed in north Georgia that I don’t get to see in Augusta.

Hiawassee, Georgia

We stayed at the Ramada Inn across from Lake Chatuge (pronounced Chatoo as in Achoo…bless you for sneezing), an artificial reservoir created by a dam that backflows the Hiawassee River.  They have a handsome living room.

Bear skin rug and other trophies decorate the living room at the Ramada Inn in Hiawasee.

The lake meanders in front and in back of the hotel, but to get to the swimming beach it’s necessary to cross a fairly busy road.  The lake abounds with green bream which swarmed around me while I swam.

View of Lake Chatuge from the Ramada Inn.

Swimming beach at Lake Chatuge.  The good looking woman in the foreground was marred with tattoos.  What is it with tattoos these days?  It used to be just bikers and sailors had tattoos and they were small and tasteful.  Now wimps and women have big ole ugly tattoos all over their bodies.

The Cherokee Indians originally settled Hiawasee which was a major village on an Indian trail through a pass between the mountains, and they lived here until 1836 when greedy white crooks kicked them to Oklahoma.

A small patch of clover behind the hotel attracted a pair of fat woodchucks every afternoon.  Woodchucks are close to the present southern limit of their range here, so I got to see another animal that doesn’t live in Augusta.  During the Ice Age woodchucks occurred as far south as Brunswick–their fossil remains having been excavated from Clark Quarry.

This is the best photo I could get of the woodchucks that live behind the Ramada Inn.  I just missed getting a closer image.  It went down the hill, eating like a little hog all the while.  Click on the photo to enlarge and look to the left of the white pvc pipe.

There are no restaurants to get excited about in Hiawasee.  The people who live in north Georgia must not believe in seasoning their food.

We didn’t get to eat at the Smoky Rings Barbecue.  They had no handicapped access–the first with no wheelchair ramp I’ve ever seen anywhere.

At Daniel’s Steakhouse my daughter ordered a sirloin steak which was grilled to perfection but unseasoned.  They didn’t season my trout either.  The average age of their customers is 70.  Perhaps that’s why the restaurant served such bland food.  Older people are supposed to watch their sodium consumption, and they probably complain if food is too spicy. I regard bland food as an abomination. 

Here’s my recipe for steak seasoning salt: 2 tsp salt, 1 tsp ground black pepper, 1 tsp celery salt, 1 tsp garlic salt, 1 tsp onion salt, 1 tsp ground coriander, a few scant drops of soy sauce.  Mix all the salts and spices on a plate.  Be careful with the soy sauce–too much and the mixture will clump up and won’t go through a salt shaker.  Pour this mixture into a salt shaker.  Sprinkle liberally over steaks and chops, or in ground sirloin for chopped steaks and gravy.

Here’s my recipe for fish coating: 1/2 cup flour, 1/2 cup cornmeal, 1 tsp ground black pepper and lots of freshly ground black pepper, 1 tsp garlic salt.  Dip the fish filets in beaten egg, then in the flour and spice mixture before frying.  Adding egg, buttermilk, and minced onion to the above recipe makes an excellent hushpuppy batter.  Cut fish fillet into fingers and dip it in the batter before frying and use the leftover batter for hushpuppies.

All-you-can-eat buffets are popular in Hiawasee.  It’s hilarious to watch how much food some of these old folks can put away.  I guess they think they’re making a profit, if their stomach capacity surpasses the restaurant’s cost of the food.

The other local restaurant we tried was called Georgia Mountain Country.  Again, bland food rules here. On the buffet blackeyed peas were served separate from ham.  The peas were unsalted, but mixing them with the ham made it acceptable.  Pole beans mixed with fatback were cooked to smithereens.  I think this recipe is based on an old pioneer dish.  The pioneers used to store pole beans by stringing them together and drying them, creating something called leather breeches beans.  To make them palatable, it was necessary to stew them with salted pork for hours.  In modern times it’s no longer necessary to cook them this way. To produce a similar taste, steam pole beans until just tender and drizzle a little warm bacon grease on them.  The cornmeal muffins served were dry as a desert and not a pat of butter in sight.  I did enjoy the baby beets, despite the lack of seasoning, because they were fresh and naturally sweet.

The best meal I ate was in a bar in Helen where we stopped for lunch on the way home.  Helen is a tourist trap–everything is more expensive because the town is built to look like a German country village.  I ate a bratwurst served on a fresh baked herb roll and smothered with sauerkraut and cheese.  Too bad I was driving and couldn’t wash it down with a beer or three.

On the way home I stopped and took a photo of the approximate location of the Great Buffalo Lick, according to Dr. Devorsey.

Approximate correct location of the Great Buffalo Lick, according to Dr. Devorsey’s research.  It’s ~.5 miles south of Buffalo Creek on Highway 22.  Today, it’s just nondescript second growth.