Clockwise Vines, Counterclockwise Vines

 

Coral Honeysuckle (Lonicera sempervirens) flowers.
Rowan County, North Carolina. 

Charles Darwin was fascinated by the growth of vines.  In 1865 he published his research in a book called On the Movement and Habits of Climbing Plants.  Among the many topics Darwin addressed was twining, how vines wrap around a support or each other to climb. He reviewed a well know observation that for a given species, the vine twines in only one direction, either clockwise or counterclockwise.   

 About 90% of twining vines grow counterclockwise but a significant minority go the other way.  A few plants can twine in either direction.  The reason for this interesting observation has been a topic of debate and research for centuries.  Many explanations have been proposed, including the movement of the sun across the sky and the Coriolis effect.  The latter is caused by the rotation of the Earth and causes hurricanes to spin counterclockwise in the northern hemisphere and clockwise in the southern.  Neither of these ideas is correct. It turns out that the twining direction of plants is genetically determined.

There are about 180 species of honeysuckles (Lonicera  sp.) and they are native to North America, Europe and Asia. All honeysuckles twine clockwise, that is, when you look at a honeysuckle vine it grows up from right to left, spiraling clockwise up its support. Coral Honeysuckle (Lonicera sempervirens) is a native of eastern North America.  With its opposite leaves and pink, tubular flowers, this striking vine is a magnet for pollinating insects and Ruby-throated Hummingbirds (Archilochus colubris).  All this pollination leads to large red fruits of Coral Honeysuckle that are a prized food for birds. 

Coral Honeysuckle flowers.
Rowan County, North Carolina.

Coral Honeysuckle Fruits.
Rowan County, North Carolina. 

Coral Honeysuckle vines twining clockwise.
Rowan County, North Carolina. 

Carolina Jessamine (Gelsemium sempervirens), is a vine found in the southern United States and down into Mexico and Central America. It has glossy evergreen leaves and brilliant yellow tubular flowers. Carolina Jessamine twines in a counterclockwise direction when growing up trees in a forest or on an arbor in a garden.  This beautiful vine has a darker side, it produces the alkaloid gelsemine.  This neurotoxin is found in all parts of the plant including the nectar.  Although many insects collect the nectar there are cases on record of Carolina Jessamine poisoning honeybees.  This usually happens when no other nectar sources are available. People can also be affected by ingesting Carolina Jessamine.  Symptoms of human poisoning include nausea, diarrhea, blindness and death.  This toxin is so notorious that Agatha Christie had a character use gelsemine in one of her books to commit murder.   

Carolina Jessamine (Gelsemium sempervirens) in flower. 
A Clouded Sulphur (Colias philodice) is drinking nectar. 
Rowan County North Carolina. 

Carolina Jessamine vines twining counterclockwise.
Rowan County, North Carolina. 

Asymmetry abounds in nature.  People can be left-handed or right handed, male fiddler crabs have one giant and one small front claw, even some organic molecules come in mirror image forms.  So, take a look at some vines and see which direction they turn.

 

 

A Flock of Seagulls

 

Ring-billed Gull (Larus delawarensis).
Lake Norman, North Carolina. 

Seagull.  The word causes birders to cringe.  Birders will tell you, that while the sea has many gulls, not all gulls are at sea.  Gulls can be found just about anywhere there is water. Oceans, lakes, rivers, marshes, bays.  Speaking of bays, if seagulls fly over the sea, what flies over a bay?  Bay gulls… bagels… get it? 

A mixed flock of  gulls.
Horry County Landfill, South Carolina. 

Gulls thrive all over the world.  You can find them from the Arctic Ocean to the fringes of Antarctica and most spots in between.  They range in size from the aptly named Little Gull (Hydrocoloeus minutus) with their 24-inch wingspan, to the gigantic Great Black-backed Gull (Larus marinus) that is a whopping 5-feet from wing tip to wing tip. Gulls are omnivorous taking whatever food is at hand.  They are equally at home snatching fish from the surface of the ocean to rummaging around a landfill eating discarded pizza crusts.  Some gulls make their living stealing food from other birds like terns.  

Immature Ring-billed Gulls.
Lake Norman, North Carolina. 

Gulls are generally white in color.  Many have gray or black on their backs and upper wing surface, the mantle. As adults, larger gulls usually have white heads, but many species of small gulls have black heads, at least during the breeding season.   Gulls generally have a heavy beak, and all have webbed feet. They can happily paddle on the surface of the water but they do not dive. The plumage of immature gulls often differs widely from the adults.  Large gulls generally take four years to reach the adult plumage, and each year have a different appearance.  Smaller gulls reach maturity in two or three years with a distinct plumage at each stage.  Gulls have a fierce look in their eyes and are graceful, elegant flyers. 

Great Black-backed Gull (Larus marinus).
Pea Island National Wildlife Refuge, North Carolina. 

The Great Black-backed Gull is the largest gull in the world.  This gull is found from northwestern Europe across the northern Atlantic including Iceland and Greenland and down the east coast of North America. In the adult form this four-year gull has a black mantle, white body and pink legs.  Adult Great Black-backed Gulls have yellow beaks with a red spot on the lower mandible. We will return to the red spot in a couple of minutes. Great Black-backed Gulls are expanding their range south along the Atlantic coast of the United States and into the Great Lakes.  They now breed on the Outer Banks of North Carolina.

Lesser Black-backed Gull (Larus fuscus).
Palm Beach County, Florida. 

Lesser Black-backed Gulls (Larus fuscus) are slightly smaller than Great Black-backed Gulls.  They are also a four-year gull, but their mantle is dark gray rather than rich black and their legs are yellow.   Lesser Black-backed Gulls are abundant in Eurasia and have recently become more common in North America, particularly in winter.  

Adult Herring Gull (Larus argentatus).
Dare County, North Carolina. 

Immature Herring Gull.
Lake Norman, North Carolina. 

Herring Gulls (Larus argentatus) are slightly smaller than Lesser Black-backed Gulls.  These white-headed, gray-mantled, yellow-legged gulls mature in four years and also have a yellow beak with a red spot.  This spot plays an important role in four-year gulls raising their chicks. The young gulls peck at the red spot on the parent's beak and this stimulates the adult to feed their baby.  The Dutch ornithologist Niko Tinbergen did important experiments with Herring Gulls in the 1940s and demonstrated this behavior is instinctual rather than learned.  For this and other research, Tinbergen shared the 1973 Nobel Prize in Physiology or Medicine.   

Adult Ring-billed Gull.
Palm Beach County, Florida. 

Ring-billed Gull in flight.
Lake Norman, North Carolina.

Ring-billed Gulls in a Walmart parking lot.
Rowan County, North Carolina. 

Ring-billed Gulls (Larus delawarensis) are the most common gulls in our area. They are three-year gulls and adults have a gray mantle, yellow legs and a yellow beak with a black ring near the tip.  Ring-billed Gulls breed in Canada and the northern United States and winter in the south from coast to coast.  Every fall around Thanksgiving Ring-billed Gulls show up in our local Walmart parking lot and feed on scraps left by shoppers.   

Laughing Gull (Leucophaeus atricilla) in breeding plumage.
Palm Beach County, Florida. 

Laughing Gull in winter plumage.
Palm Beach County, Florida. 

Laughing Gulls (Leucophaeus atricilla) are three -year gulls and are smaller than Ring-billed Gulls.  They have a black head, gray mantle, broken white eye ring and red beak during the breeding season. In winter Laughing Gulls have a mostly white head with gray at the back.  The name Laughing Gull comes from their maniacal laugh-like call.  They are found on the Atlantic and Gulf Coast of the United States and further south into Mexico, Central America, northern South America and the Caribbean. 

Bonaparte's Gull (Chroicocephalus philadelphia)
in winter plumage. This species has a white wedge on the wing.
Rowan County, North Carolina.  

Bonaparte's Gull in winter.
Lake Norman, North Carolina. 

Bonaparte's Gulls looking for a meal stirred
 up by a Common Loon (Gavia immer).
Lake Norman, North Carolina. 

Bonaparte’s Gulls (Chroicocephalus philadelphia) are small two-year gulls with a black head and light gray mantle. They have a buoyant, tern-like flight and show a white wedge on the wing in flight. These gulls breed in Canada and winter in the southern United States.  In winter they lack the black head but have a dark smudge behind the eye. Gulls are unable to dive in beneath the surface of the water, but Bonaparte’s Gulls have an interesting feeding strategy that gets around this limitation.  Small flocks of Bonaparte’s Gulls often follow Common Loons (Gavia immer) which are excellent divers.  When Loons dive, they can chase small fish to the surface where the opportunistic Bonaparte’s Gulls can scoop them up. 

Little gull (Hydrocoloeus minutus).
Lake Norman, North Carolina. 

The Little Gull is the smallest gull in the world and is native to Eurasia and North America.  They breed on freshwater lakes and winter at sea. Little gulls have a black head in summer, but in winter, like Bonaparte’s Gull, they have a white head with a black smudge behind the eye.  The most striking thing about Little Gulls, besides their size, is the underside of the wings are black.  A Little Gull showed up in December on Lake Norman in North Carolina.  This rarity was around for the Christmas Bird Count and stayed a few days so quite a few local birders got to see it.    

This rare Slaty-backed Gull (Larus schistisagus) put in an
appearance at the Horry County Landfill in South Carolina.

Slaty-backed Gull and Ring-billed Gull.
Horry County Landfill, South Carolina. 

Sometimes a vagrant gull makes an appearance in our area.  Slaty-backed Gulls (Larus schistisagus) are native to northeastern Asia but often stray to Alaska and other spots in North America.  It is a four-year gull with a white head, a slate-gray mantle and pink legs.  A couple of years ago a Slaty-backed Gull showed up at the Horry County Landfill near Myrtle Beach, South Carolina. We traveled to the landfill with friends seeking this rare gull.  It seemed unlikely we could pick the Slaty-backed Gull out among the thousands of other gulls, but we followed directions from friendly dump employees and within 10 minutes we saw the Slaty-backed Gull perched on the trash heaps with other gulls.  It may seem odd to say, but the Slaty-backed Gull looked quite elegant standing in that dump.

Immature Heermann's Gull (Larus heermanni).
Palm Beach County, Florida.

Heermann’s Gulls (Larus heermanni) are three-year gulls normally found along the west coast of North America, from southern British Columbia to Mexico.   Most of the Heermann’s Gulls breed on islands in the Gulf of California with a small colony near Monterey, California.  Adult Heermann’s Gulls are gray with a white head and a red beak.  Immature Heermann’s Gulls are dark gray, brown with a black-tipped beak.  These west coast specialties sometimes stray east.  We found an immature Heermann’s Gulls on the beach at Lake Worth, Florida one New Year’s Eve. This bird was 2500 miles from home but doing quite well among the gulls on a Florida beach.     

A flock Ring-billed Gulls and a single Herring Gull
preparing to roost on the water.
Lake Norman, North Carolina. 

Gulls have a bad reputation among some people.  Less appreciative folks call them “rats with wings”.  This name may come from their habit of hanging around dumps.  However, it is people who have given gulls an endless supply of food with our landfills as well as artificial beaches in the form of parking lots where they can congregate.  On the positive side gulls, like many scavengers, perform essential ecosystem services by eating what humans consider waste.  Another thing that has contributed to the poor perception of gulls is Alfred Hitchcock’s film The Birds. In this well know story, birds including shrieking flocks of gulls, begin to attack and kill people in a coastal California town. While I don’t really root for the birds in that movie, I think I understand their motivation.

Gulls at sunset.
Lake Norman, North Carolina.