Bald Eagles Making a Comeback

Lee McNeely, president of the Northern Kentucky Bird Club, was pleasantly surprised this past spring at the number of American Bald Eagles he spotted on the Ohio River.  One day, on an 8-mile stretch of the Ohio between Belleview and Petersburg in Boone County, he spied 7 Bald Eagles.  “That was very unusual,” said Lee.  “Usually on a good day I’ll see one, maybe two Bald Eagles.”  The sightings though are reassuring.  The Bald Eagle is finally making a comeback in Kentucky and the lower 48. 

 

“Until the 1980’s, the previous recorded nest in Kentucky was in the early 1950’s,” said Lee.  “We went a full 35 years without a single eagle nest in the state.”  The Bald Eagle, like so many other birds, had fallen victim to the effects of DDT, a now banned insecticide in the U.S. 

 

DDT, for a period of time, was a seemingly effective insecticide. It quickly killed the mosquitoes that spread malaria and the lice that carried typhus, and is credited with saving millions of lives.  Eventually though many insects developed a resistance to DDT and produced offspring that were also resistant.  DDT was also highly toxic to the fish in our waterways.  A recipe for disaster was brewing.

 

A “persistent insecticide,” the molecules in DDT stay together as a poison for a long time before breaking down into smaller, less toxic substances.  It washed deep down into the soils, our streams, and lakes.   DDT became entrenched in the food chain.  And because it does not break down easily, DDT builds up in fatty tissues where it persists for long periods of time.  It takes an animal 8 years to metabolize one-half of the DDT it consumes – more than a lifetime for many species of birds and mammals.  Birds, like the Bald Eagle and Brown Pelican, ingested DDT after eating contaminated fish.  The DDT caused their eggshells to be thin and brittle, so brittle that eggs were broken on the nest as parents sat on them during incubation.  Eagle numbers plummeted to only hundreds of nesting birds in the contiguous U.S.

 

DDT was banned in 1972.  “Eagles have been slowly re-establishing, especially in Western Kentucky,” said Lee.  “There are also a couple of nesting pairs in the Cincinnati area, one in Brown County, Ohio and another along the Great Miami River.”  According to Kentucky Fish and Wildlife, we now have a healthy population of 48 nesting pairs of eagles in the state, with another 100 to 300 over-wintering.  Having been taken off the Federally Endangered Species List, things are looking up for the Bald Eagle.  “They have recovered well and will probably continue to do so,” said Lee.

 

The United States adopted the Bald Eagle as its national emblem in 1782.  At that time there were at least 100,000 nesting eagles in the U.S.  They were at their lowest levels, about 800 nesting eagles, in 1962 when Rachel Carson raised awareness with her landmark book Silent Spring.  Now, with their numbers steadily increasing and DDT long since banned, we have approximately 20,000 nesting eagles.

  

Most would agree that the Bald Eagle is a regal bird and an appropriate national emblem, though some would beg to differ.  “Suffer me, kind reader, to say how much I grieve that it should have been selected as the Emblem of my Country,” said John James Audubon.  “He is a bird of bad moral character; he does not get his living honestly,” complained Benjamin Franklin.  Fortunately, Thomas Jefferson and John Adams disagreed with Franklin, and with the help of Philadelphia resident William Barton, the Bald Eagle was chosen as our national emblem.

 

A true American, the Bald Eagle is the only eagle unique to North America, with a range from northern Mexico to northern Alaska and Canada.  “They’re always found close to water,” said Lee.  Fish is their staple food but they’ll also eat waterfowl, turtles, rabbits, snakes and carrion.  Like other birds of prey, females are larger than males and can weigh up to 14-pounds with an 8-foot wingspan.

 

Bald Eagles mate for life and can live more than 30 years in the wild.  Their nests are an architectural marvel, which they typically enlarge yearly.  These stick nests can reach 12-feet across and weigh more than a ton.  No other bird in the world builds such a large nest.

 

Females lay one to three eggs per year, which hatch in about 35 days.  Eaglets are flying within 3 months and are no longer dependant on their parents at 4 months.  They are sexually mature and acquire their majestic looking white head and tail feathers when they are about 4 to 5 years old.

 

American Bald Eagles are more than a national emblem.  With their near extinction and successful recovery, they represent the worst and best their human counterparts can achieve.

 

Contact Gayle at her website for nest boxes at www.woodlandhabitat.com or gaylepille@yahoo.com

 

Flying Tigers

Journeyman climber Chris Bramlage of Newport was intrigued by a recent request.  A friend of his roommate’s needed someone to hang a few Great Horned Owl nest platforms in some trees, way high in the trees.  Chris can climb anywhere in just about any tree, so climbing 80-foot up a streamside sycamore was really no big deal.  He was just a little taken aback that someone would actually hang the bottom of a 55-gallon plastic drum in a tree – for an owl.

 

The bottom of a large plastic drum is actually a perfect nest for the owls.  Great Horned Owls don’t make their own nests, instead usually relying on abandoned nests of Red-tailed Hawks, squirrels or hollowed trees.  By nesting in the dead of winter, January and February, these owls don’t have to compete with the hawks and squirrels for nest sites.

 

Great Horned Owls are North America’s largest owl with ear tufts.  They are frequently referred to as the “Tiger of the Sky” for their fierce demeanor.  Get too close to nesting Great Horned Owls and you’ll likely end up in the emergency room covered with cuts from their lethal talons.  Their powerful talons have the crushing power of 500 pounds per square inch, compared with a human’s paltry 60 pounds per square inch.  Prey caught by Great Horned Owls doesn’t suffer; it is killed instantly.

 

A Great Horned Owl can easily take prey two to three times larger than itself.  They like to take the largest prey available since smaller prey costs more in energy than is benefited in food.  Common dinner fare consists of other birds, rabbits, raccoons, squirrels, mice, snakes and bats.  Since they have no sense of smell, they are one of the few animals that will readily eat skunks.  And don’t be surprised if your cat or small dog doesn’t come back home after a nightly foray.  Several Northern Kentuckians have lost small pets to this efficient and non-discriminate predator.

 

Great Horned Owls have evolved several adaptations that make them such skilled hunters.  Primarily nocturnal, they have excellent nighttime vision and can see about 100 times better than people can after dark.  Their eyes are fixed forward so when an owl wants to see something off to the side, it must move its whole head.  They have twice as many neck bones as humans, which allow them to rotate their heads 270-degrees, almost full-circle.

 

Their hearing is as good, if not better, than their eyesight.  One ear is positioned higher than the other, allowing them to hear noises from above and below.  As with other owls, their rounded face forms a facial disc, which acts as a sort of satellite dish, allowing them to receive sounds and funnel them to the ears.

 

They have up to a 5-foot wingspan, though you’ll never hear the flap of their wings.  They possess “silent flight.”  Their flight feathers are fringed in order to muffle the sound of approach.  Prey never hears them coming.

 

Now is an excellent time to hear Great Horned Owls.  They have chosen their mates and can often be heard calling to one another.  The duet is a simple call…”hoo, hoo, hoooooo, hoo, hoo.”  The male has a noticeably deeper voice than the female.

 

Soon the female will be on the nest incubating 2 to 3 eggs.  Incubation lasts about a month.  The male is always close by helping with incubation and feeding the female while she is on the nest.  Once the eggs hatch, both parents feed the ever-hungry chicks.  Young owls start branching at 6 weeks and fledge at around 2 months.  Young stay with their parents through the summer and disperse the following fall to establish territories of their own.

 

It is never wise to approach a Great Horned Owl nest.  Few birds are as aggressive in defending their nest.  They will continue to attack an intruder until it is either killed or driven off.  Their talons are formidable weapons.

 

Great Horned Owls are long-lived birds and, other than humans, have few natural enemies.  It is not uncommon for them to live close to 20 years in the wild.

 

Chris has hung 6 nest platforms for the owls in Northern Kentucky so far this year.  He’s now eager to see if any of these airborne tigers take advantage of the housing he’s afforded them. 

 

Contact Gayle at her website for nest boxes at www.woodlandhabitat.com or gaylepille@yahoo.com

 

Our Accipiters

They are the hawks that also frequent our bird feeders; only it’s not birdseed they’re looking for.  They are visiting our feeders to eat the birds we have become so attached to… our cardinals, robins, wrens, goldfinches and nuthatches.  They are Accipiters.

 

With their characteristic long tails and short rounded wing, these woodland hawks fly through the trees like fighter pilots.  Their wings allow them to quickly dodge around and between trees and branches.  The long tail aids in braking and making fast turns.  And though they’ll also eat small mammals, snakes and lizards, other birds are their primary food choice.  Our bird feeders, with dense concentrations of “feeder birds” make for easy pickins’ for these handsome and eloquent-looking hawks.  It’s a spectacle worth observing.

 

Debbie Macke of Park Hills has been watching and feeding birds for most of her 60-plus years.  She wasn’t prepared though as she watched events unfold at her home near Devou Park last winter.  At first all seemed well at her well-stocked feeders.  Then all of a sudden her birds seemingly disappeared and the few she could see were frozen in place, obviously hiding.  Above, in a tree outside her family room window was a hawk Debbie had never seen before, eyeing her feeders like a high school football player at KFC.  It wasn’t long before a wayward starling was nabbed in flight by the hawk in her side yard.  “Unbelievable,” said Debbie.  “It happened so quickly.”  A search in her Peterson Field Guide revealed the culprit, a Sharp-shinned Hawk, one of three Accipiters native to North America. 

 

Sharp-shinned Hawks (Accipiter striatus), or Sharpies, are the smallest of our Accipiters, about the size of a Blue jay.  They are the most widely distributed Accipiter in North America, inhabiting virtually all of North America into the Caribbean, Central and South America.  Mature sharpies have slate colored upper parts with a dark crown.  Their under parts are white with brown bars on the breast.  The tail is square-tipped with 3 to 5 dark stripes.

 

Sharpies are opportunistic hunters.  They’ll hunt from a perch and dart from hiding to catch prey, with birds comprising 90 percent of their diet.  They pluck their fowl before dining, and usually get sufficient miosture from their prey and drink very little water otherwise. 

 

Cooper’s Hawks (Accipiter cooperii), or Coops, are our medium sized Accipiter and are about the size of a crow.  They look very similar to Sharp-shinned Hawks and the two are easily confused.  The crown of the Coop is darker than the Sharpie, and the tail is rounded at the tip while the Sharpie’s tail is more squared.  Their diets and hunting style are similar, with birds making up the bulk of their diet.  Coops eat an extraordinary amount of food relative to their size, up to 12%of their body weight per day.  In human terms, it’s like a 200-pound person eating 24 pounds of food daily.  The Cooper’s Hawk was named after naturalist William Cooper, a founder of the New York Lyceum of Natural History in 1817, which later became the New York Academy of Sciences.

The Northern Goshawk (Accipiter gentilis) is our largest Accipiter, about the size of a Red-tail Hawk.  This bird not only inhabits North America, but is also found across Europe and Asia.   Because of its speed and fearless demeanor, it has for centuries been a favorite of falconers.  Adults are slate gray above and barred gray below with pronounced dark eye lines and crown. 

 

The common name “goshawk” is derived from “goose hawk,” and deservedly so as ducks are one of this birds favorite foods.  Goshawks though are not nearly as dependent on birds as a food source as are Coops and Sharpies.  In the Northern Boreal Forest they are so reliant on Snowshoe Hares that they will not even reproduce unless the hare population is abundant.  A more northern species, Goshawks are only rarely seen in our area.

 

All Accipiters are reverse dimorphic, meaning that females are considerably larger than males.  A female Sharp-shinned Hawk is very similar in size and coloring to a male Cooper’s Hawk.  The immature birds of all three species are brown above and lightly barred below.  Proper identification is tricky; a good pair of binoculars and field guide is almost essential. 

 

Our Accipiters are long-lived birds, and can live from 15 to 20 years in the wild.  Like so many other birds, they were severely impacted by the pesticide DDT.   Fortunately, DDT was banned in 1972 and all have made healthy comebacks.  Habitat loss is now their biggest threat.

 

Naturalist and artist John James Audubon painted and described all three of these fascinating birds.  His comments ring every bit as true now as they did in the early 1800’s…

 

“While in search of prey, the Sharp-shinned Hawk passes over the country, now at a moderate height, now close over the land, in so swift a manner that, although your eye has marked it, you feel surprised that the very next moment is has dashed off and is far away.   The food of this Hawk consists chiefly of birds of various sizes, from the smallest of our warblers to the Passenger Pigeon…”

 

“The marauder (Cooper’s Hawk) frequently attacks birds far superior to itself in weight, and sometimes possessed of courage equal to its own.  This species frequently kills and eats the Grouse commonly called the Pheasant.  Partridges and young hares are also favourite dainties.  It also follows the Wild Pigeons in their migrations, and always causes fear and confusion in their ranks.”

 

“I have found them (Northern Goshawk) rather abundant in the lower parts of Kentucky and Indiana…They caught Mallards with ease, and after killing them turned them belly upwards, and ate only the flesh of the breast, pulling the feathers with great neatness, and throwing them round the bird, as if it had been plucked by the hand of man.”

 

Contact Gayle at gaylepille@yahoo.com

 

Earth's Mass Extinctions

Extinction is nothing new to Planet Earth.  At 4.5 billion years old, the planet has endured many periods of extinctions.  There have however been a number of massive extinctions, when an overwhelming, almost unbelievable number of species were forever wiped off the face of the Earth.  They are considered mass extinctions and there have been five of them during Earth’s history.

 

“The causes are still being intensely studied,” said paleontologist Dr. Brenda Hunda of the Cincinnati Museum Center.  “Changes in climate, sea levels, sea chemistry, extensive volcanism, meteorites, and glaciations have all caused massive extinctions.”

 

“Extinction is a natural event,” continued Dr. Hunda.  “Extinction and evolution go hand in hand.    Extinction leaves open ecological space, creating a niche and is good in many ways.  Species have to go extinct for other species to evolve.”

 

And if you think Homo sapiens will rule the planet forever, think again.  “Ninety-nine point nine percent of all life that has ever lived on the planet eventually goes extinct,” said Dr. Hunda.  “Most mammals go extinct at about one million years.  Humans have large brains and can manipulate the environment.  They may last longer than many other mammals, but yes, at some point humans will go extinct.”

 

A brief description of Earth’s mass extinctions…

 

The Ordovician Mass Extinction occurred approximately 439 million years ago.  According to Dr. Richard Cowen of the University of California-Davis, this extinction occurred in two pulses.  The first happened as a big ice age began and glaciers formed causing sea levels to drop.  The second pulse occurred as the ice age ended and glaciers melted causing sea levels to rise.  Twenty-five percent of marine families were lost to this extinction event.  The fossils we so commonly see in the Cincinnati area today are from the Ordovician period. 

 

The Late Devonian Mass Extinction took place about 364 million years ago.  According to Dr. Cowen this was a major worldwide extinction of coral reefs and their associated plants and animals.  Evidence suggests an asteroid impact, or even a series of impacts on a planet that was already stressed by climatic and sea level changes.  The death toll was 22 % of marine families.  Fish were the dominant species at this time.

 

The End-Permian Extinction was about 251 million years ago and is sometimes called the Great Dying.  This was the earth’s most extensive mass extinction where 95% of all marine species of animals and 70% of land species (plants, insects and vertebrate animals) became extinct.  Dr. Cowen states that the evidence is conclusive that the cause of this mass extinction was an asteroid strike on the Earth’s surface along with the largest known volcanic eruption in Earth’s history.  A brief period of cooling was followed by a long period of intense global warming, a period of a thousand years or more, due to water vapor and carbon dioxide buildup in the atmosphere. 

 

The End-Triassic Extinction was roughly 200 million years ago.  Volcanism in what is now the Atlantic Ocean likely led to deadly global warming.  About 22% of marine families became extinct.  Dinosaurs and other vertebrates were also possibly impacted.

 

The Cretaceous-Tertiary Extinction was relatively recent, about 65 million years ago.  This mass extinction was caused by the impact of a large asteroid on the Yucatan Peninsula and beneath the Gulf of Mexico.  As with other asteroid strikes, global warming led to the extinction of numerous species of animals, including the dinosaurs.

 

According to famed Harvard biologist Dr. E. O. Wilson, after each of these mass extinctions it took more than 10 million years for evolution to replace the biodiversity lost.

 

Interestingly, global warming is associated with four of the five mass extinctions on the planet.  Politics aside, the question begs to be answered…are we in the midst of the Earth’s sixth mass extinction?

 

Dr. Hunda believes so.  “The first wave of the sixth mass extinction started 100,000 years ago when humans started migrating out of Africa,” said Dr. Hunda.  “Humans were competing with large animals causing huge mega-fauna disappearance.”

 

“The second wave started about 10,000 years ago when humans came across agriculture,” continued Dr. Hunda.  “With agriculture, humans no longer had to move around to get food.  They could stay put and build large communities.  Agriculture destroys species and ecosystems.  When monocultures are planted diversity is lost.  Humans no longer had to live as a part of nature.  Instead, they controlled nature.  Humans could take species and use them for their own purposes, and do so on a greater scale than any other species.”

 

According to Dr. Hunda, what makes this extinction different is that it is biological in nature, while previous extinctions were physical.  “This extinction is human mediated,” said Dr. Hunda.  “One species is causing the extinction of others.  Humans are a great biological agent for extinction.”

 

“We are living in a time when we can do damage to the Earth like never before seen,” said Dr. Hunda.  “We are losing species at an extraordinary rate and if it continues it could be at a level that would rival the five major mass extinction events.  It is not typical for a single species to wipe out tens of thousands of other species.  Species are going extinct before we can document them.  Things we never see will go extinct.”

 

Harvard’s Dr. Wilson estimates that we are losing 30,000 species per year, that is three species an hour.  Rain forests are thought to harbor more than half of the world’s biodiversity and are disappearing at roughly 2% annually, a yearly loss equal to the state of Florida.  Dr. Wilson estimates that for every 90% of habitat destroyed, 50% of its species disappear – often forever.  One species that is not disappearing though are Homo sapiens.  In the past 50 years humans have doubled their population.  Human population is expected to again double in the next 50 years.

 

Few scientists would argue the fact that global warming is greatly accelerating extinctions.  As the planet warms species either adapt, move north or to higher elevations.  That does not bode well for the likes of polar bears, emperor penguins, pandas and the many cold-dependant species that live on mountaintops with nowhere else to go.  More than a third of the world’s amphibian species are threatened with extinction.  “Disease is the bullet that’s killing the frogs,” said one scientist.  “But climate change is pulling the trigger.”

 

Dr. Hunda, a paleontologist who studies prehistoric life has a different take.  “Don’t worry about the planet, it will be just fine,” said Dr. Hunda.  “It’s us that won’t be okay.”

 

To learn more about our current climate change from a purely scientific point of view, listen to Dr. Richard Wolfson’s college lecture series “Earth’s Changing Climate” by the Teaching Company.  It can be found at your local library. 

Contact Gayle at her website for nest boxes at www.woodlandhabitat.com or gaylepille@yahoo.com