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Author Topic: Bald Eagles Fact of the Day  (Read 18012 times)

glogdog

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Re: Bald Eagles Fact of the Day
« Reply #45 on: May 09, 2020, 07:06:08 AM »

The Gull Wail. That's what author Gary Bortolotti describes in his book with Jon Gerrard, The Haunts and Habits of a Wilderness Monarch. It is one of the female's response to the male bringing food to the nest. He describes it as a "loud, long, drown-out cry, like some calls of large gulls, a vocalization I call a gull wail."  He goes on to say that the female will lean forward, lower her head, fluff out her feathers, and begin to call.  Does that remind you of anyone we know?  Like Mom Decorah?  :)
« Last Edit: May 09, 2020, 07:07:48 AM by glogdog »
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Iriscats

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Re: Bald Eagles Fact of the Day
« Reply #46 on: May 09, 2020, 06:10:30 PM »

More on Feet and toes

Researchers believe a bald eagle's grasp is 10 times stronger than that of an adult human hand and can exert upwards of 400 psi (pounds per square inch) depending on the size of the eagle and its talons. The average person purportedly has grip strength of about 20 psi, based on their size and gender. Bald eagle feet are covered in yellowish scaly skin. The yellowish coloration is due to carotenoids which are organic pigments. The underside of the toe is covered with fleshy knobs called (spicules) that aid in gripping limbs for perching, and also in gripping prey in flight. Eagles can open and close or unlock their feet and talons at will. If they are dragged into the water by a fish too large to lift, it is because the eagle refuses to release it, not because it is unable to let go of the prey.
« Last Edit: May 10, 2020, 11:49:24 AM by Iriscats »

pyrmum1

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Re: Bald Eagles Fact of the Day
« Reply #47 on: May 10, 2020, 07:54:26 AM »

The feet of a bald eagle are resistant to cold due to their being mainly consisting of tendons. Leg muscles, tendons & bones are what give the eagle the power to grip. Leg muscles anchored on the leg bones, close the toes & talons by contracting the tendons. Tendons are inside tendon sheaths and both have tiny ridges.  As contraction of the tendon occurs, the ridges in both tendon & sheath interlock creating, what might be called, a "ratchet" effect. This effect enables the eagle to maintain great amounts of pressure on the talons without having to use the muscle. This action enables the eagle to keep talons closed over long periods while catching or carrying large prey or perching on a branch while sleeping. The large flexor muscle or Achilles tendon automatically curls the toes inward to tighten the grip as the eagle lowers its body into a resting position.
 

« Last Edit: May 10, 2020, 07:56:06 AM by pyrmum1 »

jfrancl

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Re: Bald Eagles Fact of the Day
« Reply #48 on: May 11, 2020, 07:53:13 AM »

We are now seeing the eaglets moving around the nest more and flapping their wings. The downward wing flapping strengthens their pectoral muscles and provides the thrust for flight. Moving wings up strengthens the supracoracoideus muscles to lift the wing back up.

https://www.youtube.com/watch?v=aFdvkopOmw0
Please join us in our campaign to GET THE LEAD OUT. Together we can make the world a safer place for Bald Eagles and all wild life. We need you, THEY need you!
http://raptorresource.org/forum/index.php/topic,765.0.html

Pansie

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Re: Bald Eagles Fact of the Day
« Reply #49 on: May 11, 2020, 01:55:07 PM »

Take a breath and imagine flying like an Eagle.

An Eagle's lungs have a larger *vital capacity than an human's. Air flows in only one direction, and with the help of 9 air sacs, the Eagle takes in breath while exhaling at the same time.

The Eagle breathes in oxygen-poor blood and gives it a super boost! The air is breathed into the Eagle's nostrils (naris/nares), sent first into the lungs then into the air sacs and hollow bones. It's back into the lungs, onward to the tubules, capillaries and eventually to the heart. The oxygen-rich air goes again into the lungs, which then pours into the air sacs located in the front and back of the body. The air sacs are connected to the air spaces in the hollow spaces or *pneumatic holes in Eagle's bones.

It is the air in the hollow bones that allow the Eagle more buoyancy during flight! The Eagle may soar upwards towards 10,000 feet. Can you imagine gliding lightly on the thermals, drifting towards the ground, then soaring up again to repeat!  Effortlessly and free!


*vital capacity - the measurement of the maximum amount of air that can be inhaled or exhaled during respiratory circulation.
*pneumatic - containing or operated by air or gas under pressure.
http://animalrespriation.weebly.com/eagle.html




Iriscats

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Re: Bald Eagles Fact of the Day
« Reply #50 on: May 12, 2020, 07:15:58 PM »

For May 13, 2020

What to expect at 6 weeks.

Parental attendance drops off considerably, with parents often perching in trees nearby.

The young eaglets will pick up and play with sticks, play tug of war with siblings, hold things in their talons, and stretch and flap their growing wings.

Parents continue to feed them, while allowing them to refine some of their self feeding skills. At about 6 weeks they may start to nibble up and down prey and after some unsuccessful attempts pull off a piece, and voila, self feeding begins! They will eat as much as they can at a feeding, storing food in their crops.

They are becoming more visually acute, following their parents' coming and going.

They are almost full sized, reaching T-90(90% of total physical growth) at about 42 days of age. Bortolotti says sexes are clearly separated at 40-50 days when growth is almost complete. Feather development shows feathers on the lateral ventral surface becomes noticeable between days 26 and 45. Their brownish black feathers are becoming  apparent in rows.  The feather shafts are blue-ish color as the blood supply enters the shafts. Tarsi are full size and thickness.  Foot pads and lengths of middle toe (#3) are nearly full sized at about 40 days of age.  The bill depth is also approaching its full size, although it will continue to grow in coming weeks.  Many experts believe sex identification can now be mathematically calculated.
« Last Edit: May 12, 2020, 07:42:11 PM by Iriscats »

smileawhile

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Re: Bald Eagles Fact of the Day
« Reply #51 on: May 13, 2020, 09:12:21 PM »

For May 14

Those eagle eyes!
Just as it takes five years for eagles to reach maturity and attain those handsome white head and tail feathers, it also takes five years before we see the beautiful pale yellow eyes.
At hatch the eaglets' eyes were a uniform very dark to black color - the iris virtually indistinguishable from the pupil. 
Already you can see in close-ups that the iris is now a dark brown.
The iris will appear dark brown through the eaglets' first year.
By the second year the iris will be a lighter brown.
Third year a "cream" color.
Fourth year a dull yellow.
Fifth year - the pale yellow of a mature eagle!
As with sub adult plumages, these are just general guidelines to look for.  In nature there can always be variations in the stages of development. 

https://www.audubon.org/news/why-do-birds-eyes-change-colors

pyrmum1

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Re: Bald Eagles Fact of the Day
« Reply #52 on: May 15, 2020, 07:53:16 AM »

Bald Eagles are also called Fish Eagles. Its diet, however, also consists of small mammals, water fowl, & carrion. During much of the year, fish is an important part of an eagle's diet.  There are studies that show an average of approximately 56 - 90% of the bald eagle's diet will consist of fish.  Sometimes, the bald eagle will catch one type of fish. This can be due to the species of fish being readily available or because the fish can be easily caught.

The feet of birds of prey are designed to help them in catching & carrying prey.  The underside of the toes of a bald eagle are covered with tiny projections called spicules & these spicules help to hold on to the prey or a fish that is slippery.  The way their toes & sharp talons are designed enable them to lock on to a fish or prey.  The supraorbital ridge above the eagle's eye shades and protects the eyes which aids in fishing and hunting.  The nictitating membrane also protects the eye.
 

« Last Edit: May 15, 2020, 07:58:11 AM by pyrmum1 »

TX_Ninja

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Re: Bald Eagles Fact of the Day
« Reply #53 on: May 16, 2020, 12:04:09 AM »

The eagles have great vision. The eaglet vision is improving by the day and will improve daily as the motion component is introduced.

Besides the great acuity, range, and field of focus.. there is another component to eagle vision.  It is called "Flicker Fusion Rate."

Flicker fusion rate is the way our brain processes the optical signals from our eyes. Human eyes process about 60 frames per second. Eagles process about 100 frames per second. So while we may see a rabbit across the football field, an eagle can see the rabbit and the twitch of the whisker.

So the eagles process the visual inputs at nearly twice the rate that we humans do. It is almost like seeing the world in slow-motion to us. It is a great attribute when tracking prey at 30-100 miles per hour.

Kind of like watching a slow motion video of a sporting event, the eagles see the world that way. Pretty amazing eyesight.

eaglesrock29

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Re: Bald Eagles Fact of the Day
« Reply #54 on: May 17, 2020, 06:54:34 AM »

Happy 6 Week Hatch Day to D34 and D35!  According to Dr. Bryan Watts, T90 (the time required to reach 90% of the terminal weight) is reached between the age 36 and 42 days, depending on the gender.  Males, the smaller sex, are characterized by earlier development of feathers, faster attainment of the peak of their growth curve, and ultimately earlier flights from the nest.

Essentially, most of an eaglet's weight gain, relative to its overall body weight, occurs early on.  This is known as asymptotic growth (a pattern of growth beginning slowly, then a rapid phase, followed by a slowing of growth to full size).  Try using "asymptotic" in five sentences today lol. 

Mark Stalmaster states that characteristically, most of the growth in the early stages of development occurs in the body tissues; later gains in weight occur when the plumage grows. 

After terminal size is reached, energy demand declines to that required for maintenance alone and resembles that of adults.

Gary Bortolotti found the size difference for bill depth to be present at 20-24 days old and for foot pad between 25-29 days. These variables level off between 40-45 days. 

The approximate size differentiation between males and females is ultimately about 25% with a range of 20-30%. 
« Last Edit: May 17, 2020, 06:58:21 AM by eaglesrock29 »
"When a storm is coming, all other birds seek shelter. The eagle alone avoids the storm by flying above it. So, in the storms of life may your heart be like an eagle's and soar above." - Anonymous

gardengirl

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Re: Bald Eagles Fact of the Day
« Reply #55 on: May 18, 2020, 07:23:09 AM »

At 6 weeks we are seeing self feeding progress become more successful as neck muscles, and feet strengthen and begin to work together to grasp prey and pull and tear it apart. We are starting to see those "bad" eagle manners which will ensure better success in the wild when eaglets are on their own.  Stealing, mantling, ripping, tearing, tugging, pulling, swallowing whole, grabbing, being selfish, and gulping. 
Between the great things we can't do and the small things we refuse to do is the danger that we will do nothing at all.

jfrancl

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Re: Bald Eagles Fact of the Day
« Reply #56 on: May 19, 2020, 04:35:58 AM »

At 6 weeks old an eaglet's tarsi (ankle in humans) has reached full size and thickness. The foot pad and beak depth have also reached nearly full size at about 40 days old or about 1/2 way through the nesting period. This is when the gender identification can be calculated mathematically. Nick Fox states that around this age, the eaglets have imprinted on their parents, siblings, fear response and nest site.
Please join us in our campaign to GET THE LEAD OUT. Together we can make the world a safer place for Bald Eagles and all wild life. We need you, THEY need you!
http://raptorresource.org/forum/index.php/topic,765.0.html

glogdog

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Re: Bald Eagles Fact of the Day
« Reply #57 on: May 20, 2020, 04:51:58 AM »

Pirating: When a Bald Eagle steals food from another Bald Eagle.

Kleptoparasitism: When a Bald Eagle steals food from another species.

Juvenile: Refers to a young eaglet through its first year.

Hard Penned: Referring to the shaft of the feather after the blood supply has rescinded. While the feather is growing, the base of the feather shaft is blue from the blood supply. Once the feather has hardened and the base turns white, the blood supply is no longer flowing to the feather and the bird is referred to as hard penned.
glogdog

pyrmum1

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Re: Bald Eagles Fact of the Day
« Reply #58 on: May 21, 2020, 11:07:23 AM »

At the fish hatchery (Chuck Gipp Hatchery) the water comes from a spring, into the raceways & then into the ponds. From the ponds, the water goes to the retention pond (settling pond) across the road. From the retention pond, the water then goes back into the stream. The raceways & ponds have fish & the water does not freeze. The water coming from the spring is about 42 degrees in winter & about 57 degrees in summer.

The water is not aerated, but the hatchery does inject liquid oxygen, thereby, making the water oxygenated. The water is not circulated nor is it heated. The temperature in the holding pond, where dead fish are flushed, is not regulated.

When Mom & DM2 fish, they take the fish out of the ponds & the retention pond. The raceways are not used by Mom & DM2 because they're narrow - only 8 feet wide. An eagle's wing spans are a minimum of 6 feet. The dead & dying fish are flushed out of the tanks & into the retention pond. The eagles' taking of the dead & dying fish makes it possible for the hatchery to get rid of less fish from the retention pond.



« Last Edit: May 21, 2020, 11:15:43 AM by pyrmum1 »

smileawhile

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Re: Bald Eagles Fact of the Day
« Reply #59 on: May 22, 2020, 08:02:37 AM »

Feathers
We are all admiring the growing feathers on the eaglets. As they approach seven weeks the wing and tail feathers are still not at fledge length. 
At fledge the flight & tail feathers will actually be longer than those of a mature eagle and will continue to grow after the eaglets have fledged. The longer feathers give the immature eagles some aerodynamic advantages as they perfect their flight skills.
Then, as the subadults mature, with each successive molt the wings become progressively shorter, narrower and the tail feathers will also get shorter until they reach adulthood length.

For those of you who are numbers geeks:
Gary Bortolotti in The Bald Eagle Haunts and Habits of a Wilderness Monarch tells us that a one year old Bald Eagle exceeds its parents by:
8% in the length of the primary feathers
13% in the length of the secondary feathers
23% in the length of the tail feathers