The Tortoise and the Owl

 

Burrowing Owl (Athene cunicularia) perched above its burrow.
Florida Atlantic University, Palm Beach County, Florida.

The Gopher Tortoises (Gopherus polyphemus) and Burrowing Owls (Athene cunicularia) of Florida are on the edge.  They inhabit harsh habitats like scrub and prairie, with well-drained sandy soil. Unfortunately for them, people also covet these habitats.  First, their land was converted to farms, then to suburban housing tracts.  The tortoises and owls are being squeezed by the human population in a fast-growing state.  

Gopher Tortoise (Gopherus polyphemus).
Canaveral National Seashore, Florida. 

Burrowing Owl at the mouth of its burrow.
Florida Atlantic University,
Palm Beach County, Florida.

While Gopher Tortoises and Burrowing Owls may share the same environment, they lead very different lives.  Gopher Tortoises are found on the Coastal Plain of the southeast from eastern Louisiana to South Carolina and down the length of the Florida peninsula.  Gopher Tortoises have high domed shells and, like their namesake rodent, dig burrows. The front legs of Gopher Tortoises have large scales for protection and large claws for digging in the sand.  The rear legs are described as elephantine with large, round flat feet.  Gopher Tortoise burrows provide shelter to many other animal species ranging from Eastern Diamondback Rattlesnakes (Crotalus adamanteus) to Burrowing Owls.  Gopher Tortoises are vegetarians that may survive 60 years in the wild and over 90 years in captivity.  

A pair of Burrowing Owls.
Florida Atlantic University,
Palm Beach County, Florida.

Burrowing Owls have an even wider distribution than Gopher Tortoises, from Patagonia in South America to the high plains of Canada.  The Florida population is isolated.  Florida Burrowing Owls are over 900 miles from the western members of their species.  But during recent ice ages there was a continuous band of scrubland linking Florida to western North America and the owls inhabited it all.  Burrowing Owls are small, standing only about 10 inches tall and are active in the daytime. They have brilliant yellow eyes and their feathers are brown and white. Burrowing Owls long legged and spend much of the time standing near the mouths of their burrows. They feed mainly on insects, small mammals and reptiles. 

Gopher Tortoise.
Florida Atlantic University,
Palm Beach County, Florida.

A Burrowing Owl peering from the mouth of its burrow.
Florida Atlantic University,
Palm Beach County, Florida. 

The Burrowing Owls of western North America use the burrows of rodents like prairie dogs.  Members of the Florida population use the burrows of Gopher Tortoises but can also dig their own tunnels.  Sometimes you can see an owl tossing sand from a burrow in progress.  The burrows serve as shelter and as nest sites.  The original habitat of Florida Burrowing Owls was the Florida scrub and prairies.  As these areas were developed, the owls moved to residential areas, golf courses and airports.  

 Video of Burrowing Owl. Florida Atlantic University, Palm Beach County, Florida. 

Gopher Tortoise emerging from its burrow.
Ocala National Forest, Florida. 

Both Burrowing Owls and Gopher Tortoises are listed as threatened species in Florida.  But despite legal protection, the growth of the human population and relentless real estate development continue to push these marvelous creatures to the edge. 

Light and Water

 

A small section of a rainbow showing the
spectrum of visible light.  Otto Lake, Alaska.

The physics is well known, even simple. Reflection, refraction, absorption.  But the interaction between water and light produces spectacular effects. 

A wine glass filled with water.  The water
appears colorless. 

Look at a glass of water. It appears clear, colorless. But if you get a long enough column of water it takes on a blue hue.  Look down into a deep lake or the ocean and the blue color jumps out at you. Water absorbs the red wavelengths of light leaving the blue light and giving it the color.  

The Atlantic Ocean off Hatteras, North Carolina.
The ocean here is deep and appears deep blue because the red wavelengths
of light are absorbed by the water.  

Crater Lake fills the caldera of an ancient volcano.
The lake is nearly 2000 feet deep and is deep blue. 
Crater Lake National Park, Oregon. 

In addition to absorption, reflection also contributes to the color of water.  Reflection from the sky can change the appearance of water.  A cloudy, gray sky will be reflected from the surface and give a completely different look to water.    

Gray sky reflected on the surface of
Kachemak Bay, Alaska.

Sunrise and sunset reflected in water can produce dramatic colors.  As the sun moves, the reflections on water change with great speed.  

A beautiful sunrise reflected in Murrells Inlet,
Georgetown County, South Carolina. 

Pink morning light on Lake Norman, Mecklenburg County, North Carolina. 

Warm sunset reflected from the surface of 
Lake Norman, Mecklenburg County, North Carolina. 

Reflections of plants growing in water and animals standing in still water gives a mirror-like effect, and makes a nearly exact copy of the original. 

Snowy Egret (Egretta thula) and its reflection.
Huntington Beach State Park, South Carolina. 

Water plants reflected in still water.
Green Cay Wetlands, Palm Beach County, Florida. 

Black-necked Stilt (Himantopus mexicana) reflected
in Radicha Creek, Kleberg County, Texas. 

Blue-winged Teal (Anas discolor) and reflection.
Wakodahatchee Wetlands, Palm Beach County, Florida. 

Some of the most amazing interactions of light and water take place in the sky.  Rainbows are made by refraction of light through tiny water drops that act as prisms. The droplets divide the white light of the sun into its constituent wavelengths of red, orange, yellow, green, blue, indigo and violet.  This is the spectrum of visible light.  Many of us learned the famous mnemonic, ROYGBIV, to keep the order of the rainbow colors straight.  In a rainbow, red is on the outside of the arc and violet on the inside.  

Rainbow at Otto Lake, Alaska. 

We view rainbows with our backs to the sun. Each color, each wavelength, is refracted a different amount causing the rainbow to form.  A rainbow is really circular, but often part of the circle is below the horizon so we see it as an arc. The angle of refraction of light in a rainbow is about 42^o so the rainbow fills an 84^o section of the sky.  

Sunbow and sundogs.
Sax-Zim Bog, St. Louis County, Minnesota. 
Photo courtesy of Ms. Judy Walker. 

Another refraction-based phenomenon is a sunbow or halo.  A sunbow is a spectrum in a circle that surrounds the sun.  Sunbows are caused by refraction of sunlight through ice crystals and the angle of refraction is 22^o.  This refraction produces a halo that fills 44^o of sky, about half that of a rainbow.  Since sunbows have a smaller angle than rainbows you are much more likely to see the entire circle of a sunbow. The order of colors in a sunbow is the opposite of a rainbow with violet on the outside and red on the inside.  

Sundog. Huntington Beach State Park, South Carolina. 

Sundogs are related to sunbows and their technical name is perihelial arcs.  They are another refraction effect caused by ice crystals and are found at 22^o to the right and left of the sun.  Sundogs sometimes appear isolated and other times are associated with sunbows.  There are sundogs in the photo of the sunbow above. 

Interactions between light and water have significant cultural meaning around the world. In ancient Greek mythology, Narcissus fell in love with his own reflection in a pool of water and stared at it until he died.  This story gives us the term narcissism.  Rainbows are considered deities in diverse cultures.  Many Australian Aboriginal groups revere the Rainbow Serpent and in ancient Greece, Iris was the rainbow goddess.  Hawaii is renowned for its rainbows and there the goddess Anuenue took the form of a rainbow and served as a messenger for her immortal brothers.  In the Genesis, God sent the rainbow as a sign to Noah that the world would not destroyed again by flood.  Ancient Norse mythology has a Rainbow Bridge from Asgard to Earth.  In our time, the rainbow flag has become the banner for gay pride. On a lighter note, Ireland gave us the story of a pot of gold at the end of the rainbow, guarded by a leprechaun. In the Wizard of Oz, Dorothy longs to go over the rainbow from a monochrome Kansas.  Science and culture give us different views of water/light interactions.  This is a measure of the impact these phenomena have on all people. 

Sunset reflected in Lake Norman,
Mecklenburg County, North Carolina.