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Articles by Wayne Bierbaum

A brilliant topic

A peacock’s tail is actually brown. But it possesses structural surface properties that create a bright rainbow of hues. The colorful display is due to iridescence.
    The simplest example of iridescence is the colorful shine of a drop of oil floating on water. When the oil film is thin enough, light gets bent as it hits the oil-water interface in a process called refraction. That light may be only one wavelength, one color, as determined by the thickness of the oil. The thinner the oil, the shorter wavelength of light that bounces back. The thicker spots are reddish and the thinner bluer.
    Animals of all sorts have created structural coloration not from pigments. In some, like a snake called the rainbow boa, it is from a thin film that changes thickness and color as the snake stretches and compresses while moving. Other colors are created by a static bio-coating or structures that create refraction of a particular wavelength, as with the peacock or the throat patch of a ruby-throated hummingbird.
    The angle of the light hitting the throat patch sometimes hits that sweet spot where the refraction amplifies the bounced light. In the photos presented here —taken within two minutes — the light was too bright for my camera’s sensor. 
    Iridescence is used for coloration by many plants and animals. It is, however, uncommon in mammals. 
    Look around and decide if the color you see is due to pigment or to light-bending iridescence.

Maybe that's because it's what this sparrow eats?

    Many animals are named by the sounds they make or the food that they eat. The grasshopper sparrow is named for both. These little birds live in grasslands from Canada to Florida, where they like to perch on any stick or fence and sing a song that sounds like a flying grasshopper. They also feed on grasshopper and other grasshopper-like insects.
    In the summer, they make nests by clumping grass near the ground. Thus their nests are at risk during hay cutting. Some farmers purposefully put off cutting while the birds are nesting. With fewer open grass fields, more grass cutting and many other reasons, the population has dropped 75 percent since 1968. The Florida sub-species is almost extinct.
    To help protect populations of grass-nesting birds and animals, most states have established large tracts of grasslands that are not cut until after nesting is finished. In Maryland, the largest tracts are at Fair Hill and Soldiers Delight, with a smaller grassland at Sands Road Park.

Don’t crowd this little bird off the beach

“The birds are taking over the beach.”     

            I heard that complaint as parts of a beach were being roped off because of nesting birds.

            The bird under protection is likely the tiny piping plover. 

            In the 1850s, piping plovers were very common along the East Coast and the shores of the Great Lakes. The population collapsed as they were hunted so their feathers could decorate women’s hats. The Migratory Bird Treaty Act of 1918 stopped the hunting, and the population stabilized.

            With human development along the coast, the population was again threatened. By 1986, just 790 breeding pairs survived on the Atlantic Coast. That is when they gained protection under the Endangered Species Act. Even with protection, the most recent surveys still place the Atlantic population at fewer than 2,000 pairs. 

            Piping plovers nest in small depressions in beach sand. They lay their speckled, sand-colored eggs in depressions about the size of a footprint. The eggs are very hard to see.

            The eggs take 25 days to hatch, emerging at about the size and shape of a miniature marshmallow. The tiny chicks hide by freezing in place, as they cannot fly for another 30 days. Eggs and young are very vulnerable to predatory animals and to being stepped on or run over by motor vehicles and bikes.

            Adults also have difficulty feeding the chicks when people are too close. After the chicks have learned to fly, they are no longer as vulnerable. By September, the plovers start their migration south along the Florida coastline to the Bahamas.

            These little birds need space to survive as a species. Four thousand birds along the hundreds of miles of Atlantic coastline is not very many. Help them out by avoiding nesting areas, and keeping your pets out, too.  

Broad-winged hawks come out en masse for migration
     The fall hawk migration is still taking place. Here is a common passerby.
Whooo is the ghost owl?
       The barn owl has developed a very interesting relationship with humans. They so commonly borrow human constructions that the habit is reflected in their name. As well as barns, they are frequently found in other buildings, including church steeples. The appearance of the pale bird near cemeteries gives them the nickname Ghost Owl.
Seals come by ocean for a lie on the sand
      In the middle of the winter, tired seals haul out of the ocean, beaching at Ocean City to rest and warm up. Mother harbor seals and pups lay together, or the pups alone while the mother waits offshore.
A bug well adapted for Halloween 
      Late at night as you turn on a light, a sudden scurry catches your eye. As it disappears into a hiding spot, you are surprised by the speed and the flurry of legs.

But vultures do have some disgusting habits

      Both black and turkey vultures, also known as buzzards, are common throughout North America, especially around the Chesapeake Bay. Even more are present during the fall migration, when they fly around the updrafts of the mountains and along the coastal shores.

         You see them circling in large groups called kettles. Many spend the winter here, so you also see them on roofs and trees trying to warm up in the sun.

The California condor’s escape from extinction
     The California condor was on the brink of extinction. How close it really was, the California Department of Fish and Wildlife describes:
Like Penelope in the story of Odysseus, she spins and undoes on a daily cycle
      The large yellow garden spider (Argiope aurantia) is a very special orb weaver spider. The females are known for nightly creating a beautiful intricate web with a zigzag pattern arranged vertically in the center of the web. The spider also positions herself in the center of the web.