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Author Topic: Bald Eagles Fact of the Day  (Read 18224 times)

Bob1603

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Re: Bald Eagles Fact of the Day
« Reply #75 on: June 03, 2020, 05:30:44 PM »

FOD for June 4, 2020

Decorah Mom has been called a super-mom and for a lot of good reasons.

She is just 17 years young and yet.....
This season is her 13th clutch or brood.
She has produced 36 off-spring (that?s 3 dozen eaglets!)
She has bonded with her second mate DM2.
She once raised 3 of her eaglets all by herself from hatchlings to dispersal.
She adopted a man-made starter nest constructed by RRP (N2B).
She doesn?t migrate but stays in Decorah to protect her nesting territory all year long.
And finally,she is very likely a grandmother and perhaps even a great-grandmother.

Yes ? definitely a super-mom! 

cwellsla

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Re: Bald Eagles Fact of the Day
« Reply #76 on: June 04, 2020, 07:59:37 PM »

June 5, 2020

We are getting a lot of questions and comments in chat about branching which would be another milestone in the development for the eaglets. As we know from chat, branching is defined as a direct flight to another branch, a vertical or horizontal limb in the nest tree, not a walk up, not a hop-flap, but a flight. A little wind assist is fine, but the prerequisite is wing powered flight. Scott Nielson defines this as "the one-week period during the nine to ten week age when they move out to the branches to strengthen their leg muscles and fine-tune their balance."  He also says that they use this developmental stage to strengthen their grip, which will be important not only for perching and landing successfully after flight, but also for grasping their own food. Important to note is that branching is not a requirement, and may or may not occur before fledge.
« Last Edit: June 04, 2020, 09:01:22 PM by cwellsla »
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jfrancl

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Re: Bald Eagles Fact of the Day
« Reply #77 on: June 06, 2020, 06:06:33 AM »

June 6, 2020

The Iowa DNR has come up with some simple behaviors to look for when observing a bald eagle in the wild.  If an eagle stops its activity such as preening, then the eagle may be disturbed.  Disturbance can be from minor such as the example above to major such as flushing or permanent displacement.  They also state that if an eagle is alarmed by human presence, it may sit up in an alert posture, won't resume its previous activity and may also start vocalizing.  As the bird's agitation level increases, it might start raising its wings, shift positions and lean forward preparing to fly.  The USFW Service has suggested that there be a buffer or blind between you and the eagle as they are more likely to be bothered by activity in full view.  Cars make excellent buffers and binoculars and telescopes are great tools for eagle watching!

THE RAPTOR RESOURCE PROJECT BALD EAGLE NEST ETIQUETTE GUIDELINES: 
https://www.raptorresource.org/wordpress/wp-content/uploads/2018/04/BALDEAGLENESTETIQUETTE.pdf

« Last Edit: June 06, 2020, 06:14:23 AM by jfrancl »
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eaglesrock29

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Re: Bald Eagles Fact of the Day
« Reply #78 on: June 07, 2020, 05:55:20 AM »

It's Official - D34 and D35 are now Nine Weeks from Hatch, with that talented D36 right behind them.  Happy Hatch Day, 34 and 35! 

So what can we expect or hope for in their 9th week?   Well, for one thing, branching (while not necessary) usually happens in the 9th, week.  So put on your seat belts for hovering and branching!

Branching consists of a direct flight to another branch (either a vertical or horizontal limb) in the nest tree.  A walk up, a hop-flap, and the like don't count as a branching.   A little wind assist is fine, but the prerequisite for branching is wing powered flight.  The eaglets are strengthening their leg muscles and improving their balance.   They may also be strengthening their grip, which will be important not only for perching and landing successfully after flight, but also for grasping their own food. 

During this time period, males are often more active than females in flapping and jumping about the nest surface and in using the wing-assisted hops to reach branches above the nest.  Males typically fledge sooner than their female siblings. 

We've had a lot of questions about hovering, which, while not required, may be on our horizons this week.  The eaglets have been demonstrating some strong, flapping and hopping.  For hovering, we look for a sustained time above the nest (about 5 plus seconds), or those ever popular dangling feet. 

We are also noticing, at this point, parental visits to the nest are lessening even further.   
« Last Edit: June 07, 2020, 07:16:10 AM by eaglesrock29 »
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tulsaducati

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Re: Bald Eagles Fact of the Day
« Reply #79 on: June 07, 2020, 08:54:01 PM »

For June 8, 2020: 
Eagles have five times as many light-sensing cells packed into their eyes as humans, so they can see a lot more detail than we can. Almost all of those cells (80 percent) are cones that see color. We have only 5 percent color-sensing cones, and 95 percent rods for dark-light vision. Each of the eagle's cone cells has a colored oil droplet that acts as a filter to block some wavelengths (colors) of light, further enhancing their color vision. We can look through 5x binoculars to approximate an eagle's visual acuity, but we have no way to simulate their color vision.
-David Allen Sibley, What It's Like To Be a Bird
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smileawhile

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Re: Bald Eagles Fact of the Day
« Reply #80 on: June 09, 2020, 08:00:29 AM »

Tulsaducati posted a fascinating Fact of the Day about eagle color vision.  What about other senses, such as taste and smell?
So much genetic "energy" has gone into producing the superior eagle vision that the taste and smell senses are secondary to meeting the eagle's daily energy requirements.
Most birds (not all -  think vulture) have few taste buds and few olfactory sensors in their nasal passages. Their mouth and beak are lined with many touch sensors, so they may rely more on texture and appearance of food. 
Mark Stalmaster has stated that if foul-smelling food is covered by snow, an eagle will be unable to find it. It is believed that the size of the choanal* slit and the arrangement of olfactory sensors in the nasal passages enable birds to smell food when it is in the mouth.  This may be how they are able to reject tainted food. 
Because of this limited sense of smell, researchers do not believe birds will reject their nestlings if touched by a human!

*the slit in the roof of the mouth that connects to the bird's sinuses.

glogdog

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Re: Bald Eagles Fact of the Day
« Reply #81 on: June 09, 2020, 08:54:13 PM »

FOD For June 10, 2020
We have mentioned several times in Chat that the feathers of the wing and tail on a fledgling are longer than those of adults.  Then as the eagle matures those wings become shorter and narrower and its tail shorter with each successive molt.  The greater wing area of the immatures permits them to fly slower and perhaps soar in tighter circles (as needed in smaller thermals) then adults.  There's also a difference between immatures and adults in the speed which is most efficient for steady flapping flight.  The optimum speed depends on size and shape of the wing and weight of the bird.  Based on observations by Jon Gerrard and Gary Bortolotti at Besnard Lake in Saskatchewan, adult eagles flapping steadily in calm air fly at 28-32 mph.  Immatures with larger wings flap slower than adults.  Flapping rates of 13 immatures averaged 167 flaps per minute; of 2 near-adults, 177 flaps per minute; and of 28 adults, 188 flaps per minute. 
-Information taken from The Bald Eagle Haunts and Habits of a Wilderness Monarch by Jon M. Gerrard and Gary R. Bortolotti.
« Last Edit: June 09, 2020, 08:57:11 PM by glogdog »
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Pansie

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Re: Bald Eagles Fact of the Day
« Reply #82 on: June 10, 2020, 06:52:56 PM »

FOD for June 11, 2020

Over 800 species of birds are protected by state and federal regulations. The U.S. Fish and Wildlife states that three specific Federal laws protect eagles, fellow raptors, and various wild birds (excluding pigeons, English sparrows and starlings).

The Lacey Act, passed in 1900, makes it a Federal offense to possess, transport, sell, import or export any part of a bird, egg, or nest. It prohibits the falsification of records, labels, or identification of wildlife shipped. It also protects against the shipment of fish or wildlife in an inhumane way.

The Migratory Treaty Act, passed in 1918, states that the U.S. shall enter into conservation treaties with Mexico, Canada, Japan and Russia. This act protects birds that migrate across international borders. This includes the taking or possessing of, transportation of, and importation of migratory birds and their bodily parts, eggs or nest, except as authorized under a valid permit (50 CFR 21.11) This act was the National Audubon Society's first major victory in the conservation and protection of wild birds.

The Bald and Golden Eagle Protection Act of 1940, amended in 1962 to include the Golden eagle, stipulates that these eagles, even though no longer classified as endangered, will be protected. This includes any part of the eagle, egg and nest.



« Last Edit: June 11, 2020, 08:46:01 AM by Pansie »

Iriscats

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Re: Bald Eagles Fact of the Day
« Reply #83 on: June 11, 2020, 07:44:38 PM »

FOD for June 12, 2020

Molting.
Little is known of the molting pattern in bald eagles: perhaps future studies will help us understand this important aspect.  A molt takes place every year, although it is not known whether all feathers change annually.  Juveniles and subadults change in appearance after every molt, but adults maintain their basic coloration for life. Molt is a gradual process occurring, mostly in the summer, but extending into spring and autumn.  Because the flight feathers are not lost all at once, as is the case with some birds, eagles are never flightless during the molting period.

Ref: Mark Stalmaster The Bald Eagle
« Last Edit: June 11, 2020, 07:47:06 PM by Iriscats »

jfrancl

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Re: Bald Eagles Fact of the Day
« Reply #84 on: June 12, 2020, 05:42:41 PM »

For June 13,2020

Some Researchers have said that at 8 weeks and on, nest bound eaglets become more aware of their surroundings outside the nest and may react unfavorably to other birds nearby as well as humans nearing the nest.  Dr. Scott Nielsen stated that at this stage, they are more likely to jump from the nest if any sort of danger or disturbance comes their way.  Caution should be taken so as not to disturb them in any way in order to avoid any eaglet from accidentally falling or jumping out of the nest.

The Iowa DNR has come up with some simple behaviors to look for when observing a bald eagle in the wild.  If an eagle stops its activity such as preening, then you may have disturbed the eagle.  Disturbance can be from minor such as the example above to major such as flushing or permanent displacement.  The USFWS (United States Fish and Wildlife Service) categorizes weeks 8 through fledging as "Very Sensitive Periods" and may flush from the nest prematurely due to disruption. They suggest that there be a buffer or blind between you and the eagle as they are more likely to be bothered by activity in full view.  Cars make excellent buffers and binoculars and telescopes are great tools for eagle watching!

https://www.fws.gov/midwest/eagle/Nhistory/NestChron.html#nesting
« Last Edit: June 12, 2020, 05:44:19 PM by jfrancl »
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eaglesrock29

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Re: Bald Eagles Fact of the Day
« Reply #85 on: June 13, 2020, 08:35:44 PM »

For June 14, 2020

Congratulations to D34 and D35 for reaching their Ten Week Hatch mark!   D36 is three days behind his / her older siblings. 

It's been an exciting time this past week, seeing D34 branch, and observing lots of flapping, hopping, gaining air, riding the rails, self-feeding, stealing, and even biting Mom and DM2?s toes upon prey delivery.  That last part was not so exciting for Mom and DM2, who made quick exits from the nest.  This is the kind of aggression that we are looking for.

At ten weeks of age, the eaglets are preparing for fledge.  Generally, fledge occurs between 10 to 13 weeks of age.  Researcher Gary Bortolotti reported that a male's first flight averages 78 days, while a female's first flight averages 82 days.   The earliest recorded fledges at the Decorah Eagles (hatchery) nests have been at 74 days (D20, D24 and D28).  (Decorah North Nest eaglet DN12 fledged at 70 days this year, the earliest recorded fledge from RRP's cammed Decorah eagle nests.) 

According to Bortolotti, during the final weeks before fledge, male eaglets flap, jump and generally move around the nest and branches more than females.

As the eaglets see Mom or DM2 coming toward the nest, they are beginning to vocalize more loudly.  Although they are eating on a more adult schedule, there has certainly been an abundance of fish and mammals delivered.   The eaglets are exercising and strengthening their muscles, which will help them to self-feed more effectively and get ready for their first flight.   

The eaglets' eyes are now dark brown, their beaks and ceres are a black tone and their feathers are dark brown to black. Their feet and foot pads are yellow.  The eaglets now likely weigh about 10 pounds, give or take a pound or two, with females weighing more than males.

The eaglets are in the last stage of development -- neurological and behavioral.  They are learning to better coordinate their movements around the nest.  Imprinting on their nest site is increasing and will peak after their first flight.

The eaglets' wing and tail feathers are still growing and will continue to grow after fledge.  Even at 12-13 weeks old, some researchers have estimated that wing and tail development and growth are about 95% of a juvenile's wing and tail feathers.   Similarly, their flight muscles don't fully develop until after they've started flying.

At this stage of development, the eaglets may display defensive behavior toward other birds or humans near the nest, which, according to Mark Stalmaster, might include retreat to the opposite side of the nest or even jumping from the nest tree.  As jfrancl posted yesterday, this is a very sensitive time for the eaglets.  For anyone visiting the nest area before all the eaglets have fledged, please be particularly careful not to disturb the eaglets or the nest area, following the guidance that jfrancl provided.
« Last Edit: June 13, 2020, 08:41:11 PM 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

Faith

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Re: Bald Eagles Fact of the Day
« Reply #86 on: June 15, 2020, 08:25:31 AM »

A breeding pair of Bald Eagles has three main areas that comprise their territory.  The nest site itself, the nesting territory and the home range.  The nesting territory is generally about 1-2 square miles, and the home range about 10-15 square miles on average.  Eagles will vigorously defend their nesting territory, the nest site in particular.  They search for food in their home range, but don?t defend it.  Home ranges vary in size depending on eagle populations in the area.  Bald eagles are known to choose nest sites in areas that are similar to the site in which they were raised.  Research has found that, when they are ready to mate and breed, males tend to return to within 38 miles of their natal nest and females within 88 miles of their natal nest.  This is known as nest fidelity.

Iriscats

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Re: Bald Eagles Fact of the Day
« Reply #87 on: June 15, 2020, 08:26:57 PM »

FOD for June 16, 2020

Terms we may be using over the next few weeks

Brancher: An immature bird that can only jump from branch to branch; has developed pin feathers but has not flown
Branching:  A direct flight to another branch (vertical or horizontal limb) in the nest tree... not a walk up, not a hop -flap, but a flight.  A little wind assist is fine, but the prerequisite is wing powered flight.
Fledge:  To leave the nest and begin flying.  For bald eagles, this normally occurs at 10-13 weeks of age.
Fledgling:  A juvenile bald eagle that has taken flight from the nest, but is not yet independent.
Hover: When a juvenile is sustaining air briefly, but staying above the nest (think helicopter) and practices important landings.
Imprinting:  A distinct genetically programmed learning mechanism in which there is a permanent attachment, during a  specific sensitive period, of an innate behavior pattern in specific objects which thereafter become important elicitors of that behavior pattern.
Juvenile:  Refers to a young eagle through its first year.
Mantling:  Spreading wings and tail over its prey in a protective gesture. The action of stretching out the wings to hide food;  there is a secondary meaning describing the action of stretching a wing and the same side leg out to one side of the body.
Pirating: When a bald eagle steals food from another bald eagle.
Roosting: Perched at night in trees.
Winger: A term used for a juvenile eagle that spends a good part of its day exercising its wings,  A winger has not left the nest.

« Last Edit: June 15, 2020, 08:30:08 PM by Iriscats »

jfrancl

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Re: Bald Eagles Fact of the Day
« Reply #88 on: June 17, 2020, 07:26:18 AM »

June 17, 2020

This is a special post honoring our beloved moderator, GardenGirl1. She passed away on the evening of June 15, 2020. Our hearts are filled with great sadness but we have many memories that we will cherish for a lifetime. GG loved life, her family, friends, and our eagles. She was one of the original moderators and one of the best. May she rest in peace and soar along with Bob Anderson as they smile down upon us for an eternity.

https://www.youtube.com/watch?v=qdoSy4ROZpg&feature=youtu.be

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!
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glogdog

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Re: Bald Eagles Fact of the Day
« Reply #89 on: June 18, 2020, 02:20:02 PM »

Now that we're experiencing fledges (Congratulations D34 today at 8:40 AM), we're getting some questions in chat about Triangulation.  What exactly is that?  To triangulate is to move the head up, down, left to right, in a constant motion while looking at something (like a tree limb) or any other fixed object.   Researchers think this is how eagles judge distance between themselves and an object.  They'll sort of bob their head and move it around in circles to figure out how far away an object is.  For example today, D34 was triangulating first from the skywalk and then flew upward to another branch on the nest tree. It was about 25-30 feet away.  They may do that too if they're perched and see prey in the distance.  It's sort of like using their eyes as range finders.

Here's a perfect example of triangulating.  With permission and Thanks to Jfrancl for providing it in our chat, I am adding it on here: https://www.youtube.com/watch?v=oN7nWUM2QXY
« Last Edit: June 19, 2020, 10:09:48 AM by glogdog »
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