Raptor Resource Project Forum

Chat Moderators => Decorah Eagle Mods Want You To Know -- Eagle Education => Topic started by: tulsaducati on April 10, 2020, 02:32:21 PM

Title: Bald Eagles Fact of the Day
Post by: tulsaducati on April 10, 2020, 02:32:21 PM
At one week of age, the hatchling becomes a nestling, and continues to grow extremely quickly. By the end of its first week, the nestling may weigh around 16 ounces. At around 9 to 11 days, the secondary down (or thermal down) begins to appear.  This down is much darker, thicker, and woolier than the natal down.
Title: Re: Bald Eagles Fact of the Day
Post by: eaglesrock29 on April 10, 2020, 11:50:10 PM
For April 11, 2020

Eaglets spend most of their first week of life gaining weight. The eaglets aren't able to thermoregulate* yet, so depending on the weather and temperature, they have spent a lot of time under Mom or DM2.  We've been observing them eating, sleeping, scuffling, and growing stronger each day as they interact with one another.  They will grow from about 3.2 ounces at hatch (about the weight of 18 nickels) to about one pound in their first week.  This is an increase of about 5 times their weight in just in seven days!  Who is counting out 18 nickels now to see how much they weighed at hatch?  :)

Today, D34 and D35 are six days old and D36 is three days old!

********************************

*thermoregulate means regulating their own body temperatures.  That takes about 15 days.   
Title: Re: Bald Eagles Fact of the Day
Post by: gardengirl on April 11, 2020, 10:58:38 AM
Periods of Growth:


 eaglet: anytime from hatch to about 10 weeks from leaving the nest.

 hatchling: first week ,

 nestling: first week to fledge

, fledgling: while perfecting fledge,


 juvenile: when 1st set of feathering grows in and for the first year,

 Immature or subadult: after 1 year until adulthood.

 Some of these terms can overlap.
Title: Re: Bald Eagles Fact of the Day
Post by: pyrmum1 on April 12, 2020, 08:25:38 AM
Behaviors in raptors are: imprinted, innate (or instinctive), and learned.  A raptor's behavior comes from these 3 components and their interactions.  Imprinted behavior happens early in life and is basically unalterable, as is innate behavior.  Learned behavior can be modified during the life of the bird.
Title: Re: Bald Eagles Fact of the Day
Post by: oregonian1944 on April 12, 2020, 09:28:50 AM
Bald eagles do not have vocal chords, so the sounds they make are done by passing air through the bones in their neck.  The sound comes from an area called the syrinx where the windpipe is separated going to the lungs. They have 3 main vocalizations: contact calls between mates, peal calls which are territorial calls and begging calls from the eaglets.

Bald eagle calls: http://www.allaboutbirds.org/guide/bald_eagle/sounds
 (http://www.allaboutbirds.org/guide/bald_eagle/sounds)

Title: Re: Bald Eagles Fact of the Day
Post by: pyrmum1 on April 13, 2020, 08:31:13 AM
Imprinting has five main parts to it: imprinting on parents, imprinting on siblings, development of fear response, imprinting on a future mate, & imprinting on the type of nest style, and habitat.
Imprinting occurs within the brain of the eaglet as it focuses on its food source (the parent eagle). The eaglet recognizes another of its species and learns to recognize itself as an eagle. 
Title: Re: Bald Eagles Fact of the Day
Post by: pyrmum1 on April 14, 2020, 11:06:48 AM
Innate behavior is also called inherited behavior or instinct.  All raptors are genetically programed to react certain ways in particular circumstances in their life.  Interactions of various instincts (characteristic of the species), individual temperaments, & biological drives determine what reactions will be.  Each bird also has a different capacity for storing information in its memory. 

Examples of instinctive behavior (innate behavior) include, but not limited to: courtship behavior, copulation, nest building, incubation, and rearing of young.

Title: Re: Bald Eagles Fact of the Day
Post by: pyrmum1 on April 15, 2020, 08:01:33 AM
LEARNING:  Involuntary learning leads to involuntary response or lack of response through the non-conscious part of the nervous system. This behavior is prompt, automatic, and unthinking.

Voluntary learning produces conscious voluntary responses.  They are not automatic and are not necessarily immediate. Once it is learned, it can't be unlearned.

A fairly higher level of learning is when a bird learns a behavior through watching & trying the behavior for itself. Learning enables them to adapt to a the ever changing environment by acquiring new behavior patterns.  Most behavior has both innate and learned components. 
Title: Re: Bald Eagles Fact of the Day
Post by: jfrancl on April 15, 2020, 08:04:23 AM
Bald eagle chicks are hatched with natal (or primary) down.  Down feathers typically lack a rachis and do not form a vane.  At about 10 days of age the secondary (or thermal) down will begin to emerge.  The natal down will eventually be pushed out by contour feathers.   
Title: Re: Bald Eagles Fact of the Day
Post by: Pansie on April 15, 2020, 10:57:51 AM
Nestlings @ 2 weeks
From 9-twelve days old, the nestling's cere (the fleshy covering at the base of the upper mandible) is a pale olive color. The legs are a pale yellow color with areas still a pink-yellow color. Within certain boundaries, the nestling can thermoregulat by 15 days, having thermal down to keep them warmer.  The parent Eagles can be absent from the nest at a slightly longer periods of time. They are close by at all times, protecting their young.  The nestlings also have unique calls that prompt adults to bring them food.
Title: Re: Bald Eagles Fact of the Day
Post by: gardengirl on April 16, 2020, 07:10:28 AM
On average nestlings gain about a pound every 5 days. The male eaglet gains approximately 3.5 oz a day while the female gains about 4.6 oz a day.
The largest relative weight gains are early in the nestling time frame. Between the ages of 18 and 24 days the eaglets gain more rapidly than at any other stage of development. Bartolotti found sexual size dimorphism (females being larger) begins  to appear in some variables at about 20 days of age.
Title: Re: Bald Eagles Fact of the Day
Post by: glogdog on April 17, 2020, 06:19:53 AM
Dr Bryan Watts from the Center for Conservation Biology says there are 3 stages of development in a young eagle's life: Structural growth, Feather growth, and Neurological development.  Structural growth appears early in their development and includes primary tissue growth of the skeletal and muscular systems.  An example of this is the "clown" feet.  The second stage is feather growth: natal down, thermal down, juvenile feathers, and flight feathers which continue to grow throughout the developmental period.  Then the final stage, the neurological one, includes walking, feeding, and flying which occurs in the final month as they acquire the coordination necessary for movement and flight.   
Title: Re: Bald Eagles Fact of the Day
Post by: Iriscats on April 17, 2020, 07:46:12 PM
It's hard to see the the remiges(  flight feathers of the wings) and retrices (flight feather of the tail) emerging at 20-25 days, followed by the countour feathers at about 27days because of the thick layers of the thermal down
Title: Re: Bald Eagles Fact of the Day
Post by: jfrancl on April 18, 2020, 07:22:38 AM
At 13 days old and 10 days old, we can still see those little ear holes on D's 34, 35 and 36.  They are located below and to the right of the eyes. Eagles and other birds do not have the external "pinnae" or ear lobes that we have. Specialized auricular feathers that protect the ears while in flight will grow, and will allow sound to funnel directly to the ear.

https://www.youtube.com/watch?v=s1rACzeWQcs
Title: Re: Bald Eagles Fact of the Day, April 19
Post by: TX_Ninja on April 19, 2020, 12:14:08 AM
Iriscats's post about wing and tail feathers reminded me of this video of a golden eagle.

Golden Eagle in slow motion Earth Unplugged https://www.youtube.com/watch?v=aM0JMoGABgk

retrices = director/helmsman = tail feathers;    remiges = oarsman = wing flight feathers
I like the video. The Latin definitions of the feathers make sense

I was the geek that took Latin in high school, so I like the Latin explanations for the different feathers. Kind of a cool feather and flight demonstration and explanation.

Not long and the eaglets at Decorah will begin to sprout their "real" feathers.
Title: Re: Bald Eagles Fact of the Day
Post by: Iriscats on April 19, 2020, 06:23:56 PM
One thing we don't have to worry about in Decorah, is a deficiency in their diet, which would slow down or stunt the growth of the long bones in week 3.

This is also when their brain is developing. According to Nick Fox, most of the sensitive period of aspects of imprinting is at this time.
Title: Re: Bald Eagles Fact of the Day
Post by: pyrmum1 on April 20, 2020, 08:00:29 AM
At three weeks, the eaglet is pretty well covered with its second coat of down (thermal down).  Around days 18-22, natal down has all but disappeared except for the head

The eaglet's legs begin to change to yellow at three weeks of age. Their weight gain during days 18-24, is around 4 ounces a day. This weight gain is a bigger weight gain than any other time in their development.  By the end of the 3rd week or beginning of 4th week, their weight may be about 5 pounds and they may stand about 1 foot tall.
 
Title: Re: Bald Eagles Fact of the Day
Post by: smileawhile on April 20, 2020, 09:37:06 PM
for April 21
[/b]
Coming to Terms
Thermogenesis - a fancy word for shivering
Although temperatures are finally warming up, Decorah can still have some cool mornings, or even cool days. 
Chatters have noticed the eaglets shivering sometimes when not shielded by a parent.  Birds and most critters, including humans, have this capability.  The muscle action of shivering generates heat to help keep the core warm.  Now the eaglets are sprouting a good insulation of thermal down, so thermogenesis and thermal down (thermoregulation) will help keep them warm when not being "tented" by Mom or DM2.
Title: Re: Bald Eagles Fact of the Day
Post by: jfrancl on April 21, 2020, 05:56:01 AM
Today 4/21, the eaglets are 16 days old and 13 days old. At 2 weeks of age the nestling should instinctively back up to the edge of the nest and defecate over the side.

They will have unique calls that prompt adults to bring them food. Their gray thermal down is replacing the natal down. They are approximately 2 pounds now and will be brooded less often.  Beaks and clown feet are growing fast, and now the eaglets will be exploring the nest more.

 https://www.raptorresource.org/2019/04/12/eaglet-growth-and-development-week-two/
Title: Re: Bald Eagles Fact of the Day
Post by: Pansie on April 21, 2020, 01:46:46 PM
The Curious Case of the "Crop'
 The crop, that muscular pouch near the gullet or throat, has drawn the curiosity and amazement of many a viewer. The questions abound: What is it? How much can it hold? Can it get any larger! Do all birds have a crop?

The crop is a pantry of sorts, below an eagle's chin, which temporarily stores food. It is an expandable section of the esophagus. An adult eagle's stomach is quite small, about the size of a walnut. The eagle can eat up to 1/3 of their own body weight in food. The food is stored in the crop, where it is moistened, softened, and then moved through the digestive tract as needed.

It never ceases to amaze viewers how large the crop can get! At times it's a wonder the eaglets can maneuver with that large protruberence! To our surprise and laughter, they handle it quite well!  In a adult eagle, the crop may be visible when the feathers are blown about in the wind.

Adult eagles do not need to eat daily. In the case where food sources may not be readily available, an eagle can gorge on food that is available, and hold up to 2 pounds of food in their crop.

Not all bird species have crops.

Hopefully this bit of information will ease curiosity a bit, however, isn't it marvelous how nature has taken care to ensure that our loved Raptors will eat well!
Title: Re: Bald Eagles Fact of the Day
Post by: Iriscats on April 22, 2020, 11:55:50 AM
According to US Fish & Wildlife Service, bald eagles have been found to prey or take as carrion 46 species of birds, 20 species of mammals, 18 species of fish, 5 species of turtles, and 2 species of invertebrates.

On Decorah nest prey seen in the past has included, cottontail rabbit,muskrat,fox, squirrel, grey squirrel, coot, gosling, grebe, various other birds, fawn (likely road kill) piglet, raccoon, and fish including rainbow trout,redhorse sucker and white sucker.

That's why it is sometimes difficult to tell what has been brought in.
Title: Re: Bald Eagles Fact of the Day
Post by: eaglesrock29 on April 22, 2020, 10:20:20 PM
For April 23, 2020

At 18 days old today, D34 and D35 are beginning their rapid growth period, which comprises Days 18 through 24.  During this time, eaglets gain about 4 oz per day, more weight than at any other stage of their development.  The size difference between females and males will begin to emerge after 20 days.  Gary Bortolotti found that sexual size dimorphism* for bill depth is present at 20-24 days and for foot pads, between 25-29 days. 

While females gain weight faster than males, males develop their plumage and achieve other milestones faster than females. 

There are so many things to observe and learn over the next week!
_______________________________________

*In birds of prey, generally the female is the larger gender (approx 25% larger and up to 30%)
Title: Re: Bald Eagles Fact of the Day
Post by: smileawhile on April 23, 2020, 10:00:21 PM
for April 24, 2020

Eaglesrock has posted a very informative FOD on eaglet development, so to continue the topic I would like to add this tidbit of information -
Mark Stalmaster, in The Bald Eagle, tells us that the bald eagle has an S shaped growth curve.  Development is rapid the first month, slows
during the second month, and levels off in the third month.  In that time the eaglets will grow from about 3.5 oz to 8-10 or 11 lbs, depending on the sex.
Title: Re: Bald Eagles Fact of the Day
Post by: tulsaducati on April 24, 2020, 03:51:24 PM
This week we start to watch for the appearance of pin feathers along the edges of the eaglets' wings. Pin feathers are new developing feathers that are surrounded by protective keratin sheaths, and they begin to appear at about two to three weeks old. While a feather is growing, it contains nerves and blood vessels, and the base of the feather shaft is blue from the blood supply.  Once the feather has hardened and the base has turned white, the blood supply has rescinded and is no longer flowing to the feather.  The feather is then referred to as hard penned. You can see closeups of pin feathers in this video at 8:08 in: https://youtu.be/D6muMqT17wI (https://youtu.be/D6muMqT17wI).
Title: Re: Bald Eagles Fact of the Day
Post by: glogdog on April 25, 2020, 06:18:06 AM
Everyone seems to enjoy watching young eaglets do "poop shoots" out and over the nest.  So what exactly are poop shoots made of?  They are made of feces, urates, and a clear liquid part.  The final form of waste excreted is a white semi-solid.  The proper term to use when describing eagle defecation when it is seen is "sliced".  The white strand of projected excrement is properly called a slicing.  Bird droppings are also called mutes.

https://youtu.be/f9OPtqv5Bg0
Title: Re: Bald Eagles Fact of the Day
Post by: jfrancl on April 26, 2020, 06:16:34 AM
Adult bald eagles require approximately 1 to 1.5 pounds of fish/prey per day.  This includes energy for metabolism and maintenance as well as energy for flying, hunting and other activities.

Energy demand for eaglets includes maintenance requirements, plus energy for growth and development.  Peak energy demand occurs in the later stage of rapid growth when metabolic demand is high due to large body size and when eaglets are still growing at a rapid rate.  After terminal size is reached, energy demand declines to that required for maintenance alone and resembles that of adult food intake. One reliable outward sign that chicks have moved past the period of most rapid growth and peak energy demand is when they begin to appear mostly feathered.
Title: Re: Bald Eagles Fact of the Day
Post by: pyrmum1 on April 26, 2020, 11:58:28 AM
From the USFW states that there are 5 phases of sensitivity relating to human activities & nesting bald eagles:

Phase 1: Courtship & nest building.  This is a sensitive period & can result in eagles leaving the nest for good.

Phase 2: Egg Laying.  Human activity can cause eagles to desert/abandon the eggs for the season.

Phase 3: Incubation & Hatching. A sensitive period where adults take wing suddenly due to human activity & this leaves the eggs vulnerable.

Phase 4: Nesting period 4-8 weeks. This is a sensitive period due to nestlings missing feedings & this can affect their survival.

Phase 5: Nestlings 8 weeks to fledging. This is a very sensitive period to human activities. This could cause the nestlings to prematurely fledge and perish.

As you can see, any human activity can have devastating effects on nesting bald eagles. When visiting a nest area, if an eagle stops its activity, i.e. preening, looks toward the activity it hears, such as loud voices, etc., then you have disturbed the eagle. It is always best to stay a long way back from an eagle's nest & use binoculars. The view will be great & no harm is done to the eagles by viewing in this manner.
Title: Re: Bald Eagles Fact of the Day
Post by: Iriscats on April 26, 2020, 05:05:25 PM
When eagles roost along rivers, lakes or reservoirs they are most likely to choose deciduous trees. In the midwest they prefer cottonwoods.

The scientific name is Populus deltoids. Common name is Eastern Cottonwood.   Like the eagles they are the fastest growing commercial forest species in North America. A young tree can add 6 ft or more each year. Bark is thin and smooth on young stems, but develop into gray to almost black and heavily fissured mature trunks.   The average tree is 60-100 foot tall with 60-100 foot canopy spread. Trunk diameter is 5 to 6 feet.

Cottonwoods are closely related to poplars and aspens with which they share the trait of shaking, shimmering heart shaped leaves which turn bright yellow in the fall. Cottonwoods can be either male or female. It is the female that produces fluffy white cotton like seeds.
Title: Re: Bald Eagles Fact of the Day
Post by: Pansie on April 27, 2020, 09:58:50 AM
Tough as Nails
Consider the 'talon', the razor sharp part of an Eagle's foot that serves various purposes such as mobility, perching, fishing, hunting,and defense.

According to Peter Nye, with the New York Department of Environmental Conservation, eagles have 4 talons (and toes) on each foot. The halluxtalon  is the longest and heaviest and faces backward. In humans the hallux would be considered the big toe. The other three toes (and talons) face forward. Each toe is covered with keratin scales and is tipped with a talon that is approximately 2-3 inches long. As with an Eagle's beak, the talons are a constantly growing layer of keratin, over a core of bone, and like the beak, they are kept in check by constant wear.

The color of an Eagle's talon is due to carotenoids which are organic pigments. The underside of each toe is covered with spicules (fleshy knobs) that aid in gripping limps for perching, and also gripping prey during flight. It is interesting to note that when an eagle is carrying it's prey during flight, it carries it away from it's body and eyes, thus protecting itself from any harm.

A good point of reference is the fact that a talon is similar to a dog's nails. 

Title: Re: Bald Eagles Fact of the Day
Post by: oregonian1944 on April 28, 2020, 08:07:03 AM
During the 3rd week the eaglets brains are developing. You've heard the term "imprinting".  Eaglets first imprint on the sound and then the sight of the parent as a food source.  Secondly, they imprint on their siblings at about the time they are getting their secondary (thermal) down. Once they have imprinted on their parents and then their siblings, they also have imprinted on their nest, surrounding area and their fear response develops.  Anything that is unfamiliar to them now, elicits the fear response, such as a human, an animal, or other avian. According to Nick Fox, "this is the most sensitive period for the various aspects of imprinting.
Title: Re: Bald Eagles Fact of the Day
Post by: Iriscats on April 28, 2020, 06:16:34 PM
for April 29,2020

Within the first month they will begin to cast pellets which are indigestible parts of prey (some bones, fur, feathers and scales) which are formed and compacted in their gizzards.  We will also notice them grasping with their talons, and may attempt to peck at food in the nest even though they are not ready to self feed yet. They are already grabbing at food in their parent's beak, not waiting to be fed, but snatching and gulping enormous chunks of food.

Title: Re: Bald Eagles Fact of the Day
Post by: pyrmum1 on April 29, 2020, 07:54:35 AM
A bald eagle's feathers are important for flight, regulating body temperature, & are useful for territorial, social & courtship displays. Feathers also help keep certain areas of the body clean from debris & transmit information to nerve receptors in the skin (e.g. wind currents).  Bald eagles have approximately 7,000 feathers.  The feathers of a bald eagle weigh twice as much as their skeleton (which weighs about half a pound).  Thirty bald eagle's feathers weigh about the same as a penny (.088 ounces). 

Feathers protect an eagle from the cold and sun by trapping layers of air.  A bald eagle will change the position of the feathers by ruffling & rotating them. This action aids in maintaining their body temperature & the air pockets are opened to the air or drawn together to reduce the insulating effect.  Its feathers allow bald eagles to live in extremely cold environments.
Title: Re: Bald Eagles Fact of the Day
Post by: tulsaducati on April 30, 2020, 08:45:57 AM
April 30, 2020
Bald eagles keep their feathers in good condition by preening, which involves removing dirt, smoothing, and distributing oil that comes from a gland near the base of the tail called the uropygial or preen gland. Ornithologist Frank Gill describes it as a rich oil composed of waxes, fatty acids, fat and water.  The gland has pores that secrete the oily substance.  Preening is rubbing the head and bill over the gland pores, redistributing the oil to feathers, legs and feet. Dr. Ford states, "It was once thought that applying oil to the feathers helped make them waterproof and helped in the production of Vitamin D.  We now know that the feathers are naturally waterproof by microscopic structure and that Vitamin D is not produced from the preen oil photo-degrading on the feathers. The oil most likely acts as a conditioner to moisturize and protect the proteins in the feathers to keep them pliable."
Title: Re: Bald Eagles Fact of the Day
Post by: Iriscats on April 30, 2020, 07:55:31 PM
May 1, 2020

Pin feathers continue to develop. They are also known as blood feathers because they are connected to the blood supply which emerges from the skin's feather follicle and allows the feathers to grow. The emerging feathers will initially be surrounded by heavy layers of down. The dark feathers are arranged in tracts beginning with the head (capital) and back (dorsal) tracts. The (ventra)l or belly feathers are the last group to appear. Males develop plumage earlier than females. Their feet and eyes are growing fast and nearly full size during this stage
Title: Re: Bald Eagles Fact of the Day
Post by: cwellsla on May 01, 2020, 11:52:03 PM
May 2, 2020

Juvenile flight feathers start growing at about 27 days, although feather growth does not overtake structural growth until thirty-five to forty days after hatch. The flight feathers of the wings are called remiges and are of two kinds: primaries and secondaries. Primaries are 10 in number and are attached from each wrist to the wing tip. They aid in providing forward lift or thrust in flight and help in stability and maneuverability during flight. Secondary flight feathers, or secondaries, are mid-wing, and are 16 in number. In bald eagles, they make up most of the body's surface area, going from the wrist to the elbow and aid in vertical lift. When bald eagles have attained their mature size, their wing feathers will extend to within an inch of the tip of their tail feathers.


You can clearly see the primaries and secondaries at work in this slow motion video:
https://youtu.be/thEkFMaB5CA?t=33 (https://youtu.be/thEkFMaB5CA?t=33)
Title: Re: Bald Eagles Fact of the Day
Post by: glogdog on May 03, 2020, 07:16:37 AM
One type of learned behavior is Voluntary learning.  It produces voluntary conscious responses.  They are not automatic and not necessarily immediate.  Voluntary learning includes insight which assumes the bird has knowledge or understanding of a situation.  Insight can come from watching parents and siblings and then joining in.  An example would be a young eaglet watching its parents de-fur or de-feather prey.  At some point the eaglet will attempt to do that on its own.  Insight learning is relatively permanent.  Once knowledge is gained it can't be unlearned.
Title: Re: Bald Eagles Fact of the Day
Post by: eaglesrock29 on May 03, 2020, 07:43:08 AM
D34 and D35 are four weeks old today and it's just a few more days for D36!  At four weeks, the eaglets are grasping with their talons. They may attempt to peck at food, although they are not yet ready to self-feed (hmm, what to do with those feet lol). 

They may grab at food in their parent's beak, not waiting to be fed, while snatching and gulping enormous chunks of food.  Within the first month, they have begun to cast pellets which are indigestible parts of prey (some bones, fur, feathers and scales).   Pellets are formed and compacted in their gizzards.  Think about those fish tails they have been consuming  :)

Males are developing plumage earlier than females.  Male eaglets may gain about 3.6 oz per day, while females may gain about 4.59 oz per day.  After 20-30 days, the weights of the two sexes begin to diverge or separate and sexual size dimorphism begins to appear.  The quicker rate of female weight growth results in their lifelong difference in size. 
Title: Re: Bald Eagles Fact of the Day
Post by: pyrmum1 on May 04, 2020, 07:45:39 AM
Frank Gill says the avian heart is approximately 41% larger than a mammal's heart of similar size.  The avian heart can also pump about 7 times as much blood as a human heart. The heart of a bald eagle has 4 chambers & is very similar to a human heart except that the eagle's aorta bends to the right instead of to the left as in humans.  The avian heart rate varies with the size of the bird.  An eagle's heart rate may range between 120 beats per minute (BPM) for a calm bird to 300 BPM for an excited bird. The heart rate can jump from 120 to 300 instantly when suddenly excited. Like other birds, their heart rate is generally higher than a mammal of the same size.
Title: Re: Bald Eagles Fact of the Day
Post by: jfrancl on May 04, 2020, 07:47:09 AM
We are often asked what kind of tree the nest is in. N2B was built in a male Cottonwood tree. The scientific name for the cottonwood is Populus deltoides.  The common name is Eastern Cottonwood.  The female Cottonwood produces cotton-like seeds but both male and female trees grow heart shaped leaves. The cottonwood is classified as a hardwood although the wood is lightweight and rather soft.  The average tree is 60-100 feet tall with a 60-100 foot canopy spread. They grow best on moist, well-drained sands or silts near streams.

N1 and N2 were also constructed in male Cottonwood trees.
Title: Re: Bald Eagles Fact of the Day
Post by: smileawhile on May 04, 2020, 08:39:32 PM
Post for May 5

Coming to Terms!
Digitigrade - animal or bird that walks on its toes (digits) as opposed to -
Plantigrade - foot flat on the ground (humans).
Eagles are digitigrade (what a great vocabulary word!).  We see that starting in week 4 our Decorah eaglets are gaining the muscle strength to stand.  The nest is certainly not a very firm, stable surface to practise walking but the challenge will actually help them strengthen those leg muscles.  This will enable them to "prance" about on those huge toes to explore their beautiful (eaglethood) home high up in the cottonwood.

Here is a link with some anatomy diagrams:
https://www.donqmedia.net/word-of-the-moment/plantigrade-digitigrade-and-ungulate/

and here is a link for everything you could possibly want to know about bird feet and legs!
https://en.wikipedia.org/wiki/Bird_feet_and_legs

Enjoy!
Title: Re: Bald Eagles Fact of the Day
Post by: Pansie on May 05, 2020, 09:30:46 AM
On the Defense
During the first month of life, our eaglets either ignore an intruder or react to it as they would to the parent bird. Mark Stalmaster, author of The Bald Eagle, writes that they may even beg for food from a researcher who may climb into the nest.  However, this is soon replaced with a defensive mode. At five to six weeks of age, our nestlings will raise themselves up and call threats to any intruder who may dare come near the nest. At six to nine weeks of age the eaglets will become even more defensive, as they spread their wings, ruffle their feathers, open their beaks and hiss, and even display or strike with their talons. How fierce our eaglets can be!

An interesting note by Stalmaster states that an adult eagle may lay prostrate in the nest, feigning death, attempting to divert the attention of the intruder. The adult eagle may assume a stooped shoulder posture, wings held limp and heads bowed. Recall early on after hatching, the pecking that went on, the prone posture of the one pecked, the submissive behavior that puzzled some viewers.  Now we understand why, the instincts which play such a large part in their growth.


Title: Re: Bald Eagles Fact of the Day
Post by: tulsaducati on May 05, 2020, 05:24:54 PM
Answering a couple of camera questions we've been seeing in chat:
The new view of the retention pond we have been seeing recently is provided to us by the new (replacement) camera that was recently installed atop the Visitor Center at the hatchery.  It looks across the retention pond back toward the N2B nest.  This camera also provides the view of Mom and DM2 when they perch on M2, the new maple tree location (the one that Mom moved to when the old maple had to come down).There is a certain amount of movement and vibration visible in this view from this camera; rather than the camera being attached to a sturdy tree trunk or limb like the other cams are, it is attached to a pole, and it just isn't possible to achieve the level of stability to prevent any movement. It doesn't take much movement to affect the view.
Title: Re: Bald Eagles Fact of the Day
Post by: eaglesrock29 on May 06, 2020, 08:36:49 AM
Well, the eaglets are all 4 weeks old and counting.  Happy 4 Week Hatch Day, D36!   Week Five offers more wonderful developments to observe: 

At 5 weeks, they should measure approximately 24 inches from head to tail and weigh about 6 pounds!  When the eaglets are 5  to 6 weeks old, they can stand uprightly, may start to scream loudly, and attempt to tear up their own prey. 
 
The eaglets are beginning to preen regularly.  Preening removes dirt, smoothes their feathers, and distributes oil from the uropygial gland near the tail, which helps to keep the feathers healthy.    It may look itchy to some viewers but some some studies concluded that it is not.
 
Get ready! We will soon begin to see vigorous flapping, hopping, and moving about the nest!   

They will only need to be brooded in harsh weather.
Title: Re: Bald Eagles Fact of the Day
Post by: Iriscats on May 06, 2020, 08:12:27 PM
For May 7,2020

Feet and Toes

A bald eagles toes are part of its skeletal structure. An adult bald eagle's foot measures about 6 inches from front to
back excluding talons. Toes are numbered beginning with the back toe as digit 1, inner toe as digit 2, middle as digit 3,and the outer toe as digit 4. Each toe is made up of separate bones (singular=phalanges:plural=phalanx) Three of the toes point forward and the hallux points backward (in humans the hallux][ is the big toe) this toe arrangement is called anisodactyl.  The toes close securely much as human]s can clench our hands into fists.  Birds are called digitigrade because they actually walk on their toes and not on all of the foot bones (as humans do)
Title: Re: Bald Eagles Fact of the Day
Post by: tulsaducati on May 08, 2020, 07:40:32 AM
How are feathers formed? Each new feather grows from a small outgrowth of skin called the papilla. As feathers mature, their tips get pushed away from the papilla, where the newest parts of the feather form. Like human hair, feathers are youngest at their base. The feather's structure develops as proteins are laid down around the surface of this bump of skin. It's here that the branching patterns form by smaller branches fusing at the base to make thicker ones' barbules fuse into barbs and barbs fuse into a rachis. As the feather grows, it stays curled in a tubular shape around the papilla until it is pushed away from the growth area. A protective sheath maintains the feather's cylindrical shape until it starts to disintegrate near the tip, allowing the mature part of the feather to unfurl. The sheath falls off and the feather growth process is complete.  From Cornell University's Academy.Allaboutbirds.com.  https://academy.allaboutbirds.org/feathers-article/2/ (https://academy.allaboutbirds.org/feathers-article/2/)
Title: Re: Bald Eagles Fact of the Day
Post by: glogdog 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?  :)
Title: Re: Bald Eagles Fact of the Day
Post by: Iriscats 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.
Title: Re: Bald Eagles Fact of the Day
Post by: pyrmum1 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.
 

Title: Re: Bald Eagles Fact of the Day
Post by: jfrancl 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
Title: Re: Bald Eagles Fact of the Day
Post by: Pansie 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




Title: Re: Bald Eagles Fact of the Day
Post by: Iriscats 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.
Title: Re: Bald Eagles Fact of the Day
Post by: smileawhile 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
Title: Re: Bald Eagles Fact of the Day
Post by: pyrmum1 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.
 

Title: Re: Bald Eagles Fact of the Day
Post by: TX_Ninja 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.
Title: Re: Bald Eagles Fact of the Day
Post by: eaglesrock29 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%. 
Title: Re: Bald Eagles Fact of the Day
Post by: gardengirl 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. 
Title: Re: Bald Eagles Fact of the Day
Post by: jfrancl 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.
Title: Re: Bald Eagles Fact of the Day
Post by: glogdog 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.
Title: Re: Bald Eagles Fact of the Day
Post by: pyrmum1 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.



Title: Re: Bald Eagles Fact of the Day
Post by: smileawhile 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
Title: Re: Bald Eagles Fact of the Day
Post by: Pansie on May 22, 2020, 09:32:15 AM
Foraging
Eagles have numerous methods of foraging for food. As we know they are considered 'opportunistic' eaters. Of course the easier the better, and they have no qualms about stealing from another source. Are they often considered 'lazy', yes, but we need to realize that when the opportunity becomes challenging, they will rise to the occasion. They can be quite serious about their meals.

According to Mark Stalmaster, author of 'The Bald Eagle', early evolutionary adaptation may have been genetically passed on through generations. Perhaps food was scarce in the early times, and the Eagle became adept to stealing from others in order to survive. (This may also be where imprinted behavior plays a part as the parent raises their brood.)

The NOVA special, Eagle Power, showed us a bit of the different methods of foraging.  We saw 'aerial chases', where they attacked and caught their prey in the air. There is the 'running or walking' attack, where they will pounce on opponents and battle fiercely with their talons or wings, always being careful to protect their eyes.

There is also the 'mock attack' where an Eagle will show force, then back off a bit, testing the will and strength of the opponent. Smart raptor!

As we watch these eaglets,  we may view 'beaking', jabbing or striking at another to drive it away. They may scream at the competition. Fluff their feathers and thrust their wings forward.  The 'beaking' Eagle will hold it's head and body lower over the food source, reducing the chances of attack. Also 'mantling',(which we have often seen), in which they will cover the food with their body and outstretched wings.

All methods are ways in which the Eagles shall find the food they need to sustain their offspring and themselves.





Title: Re: Bald Eagles Fact of the Day
Post by: jfrancl on May 23, 2020, 12:36:42 PM
Imprinting is defined as a genetically programmed learning mechanism formed during a brief receptive period. This usually occurs soon after hatching and generally establishes a strong long lasting behavioral response to an object or a specific individual, such as parents or siblings.

Environmental imprinting starts on the nest and immediate surroundings. After fledge they imprint on a larger area which may include rocks, cliffs, man made structures and so on.

Habitat and geographical imprinting or environmental imprinting, are important to birds that disperse a great distance and are migratory, then those who are more sedentary,  as they will need to hone their abilities as to what habitat and nesting area is important to look for as adults.  Studies have shown that there are strong parallels between the type of nest in which a young eaglet has been reared and the type of nest they will choose or build as adults. 1st time breeding birds will look for a similar habitat in which it was raised, often a short distance from their natal nest area.
Title: Re: Bald Eagles Fact of the Day
Post by: Bob1603 on May 23, 2020, 03:32:22 PM
We often hear the eagles vocalizing and it is interesting to note they are able to do that without any vocal cords.  They have bones in their throat and their hi-pitched, shrilling, squeaking, and screeching sounds are made by passing air over those bones.  All of this is done in an area of the throat called the syrinx that is located at the posterior end of their trachea where the windpipe is separated going into the lungs.  The syrinx is similar to the larynx of mammals.  Syrinx is derived from a Greek word for pan pipes. 
Title: Re: Bald Eagles Fact of the Day
Post by: Iriscats on May 24, 2020, 09:22:29 AM
May 24, 2020

D34 and D35 are 49 days old today.  They have reached 7 weeks. D36 is 46 days old, and here is what we can expect.

The ability to self-feed is evident at about the 6th to 7th week although, it will be a long time before the young birds become proficient.  They are almost as large as their parents.  By 7 weeks of age, young eagles have attained almost their full fledge weight and very much look ready to fly, but the tail feathers have only started to lengthen and their wing feathers are well below fledging length.

Title: Re: Bald Eagles Fact of the Day
Post by: Faith on May 25, 2020, 03:40:23 PM
We are often asked how we will know if the eaglets are male or female.  The truth is we will likely never know.  The only way to be 100% accurate in determining the gender of an eagle or eaglet is by doing a DNA or blood test.

Another method often used is the Bortolotti Rule, which uses measurements of the bill depth and hallux length in a formula to determine gender.  The formula is (Bill depth X 0.392) + (hallux length X 0.340) - 27.694, in centimeters.  A positive result = female.  A negative result = male.  This method is about 90% accurate.
Title: Re: Bald Eagles Fact of the Day
Post by: pyrmum1 on May 26, 2020, 08:16:22 AM
Metabolism is defined as a set of chemical reactions occurring in cells of living organisms to sustain life.  These chemical reactions allow organisms to grow and reproduce, maintain their structures, and respond to their environments.  Flying requires a higher body temperature & a faster metabolic rate. Smaller birds have a faster metabolic rate than larger birds, i.e. raptors. Researcher, Nick Fox, states there are 3 types of raptor metabolism:

1) basal metabolism,  the energy needed to keep basic bodily functions operating and to keep the heart beating

2) existence metabolism, the extra energy a raptor needs to cope with effects of temperature and climactic changes on its body, such as wind and rain

3) productive metabolism, energy needed for activities such as hunting, courtship,
Title: Re: Bald Eagles Fact of the Day
Post by: oregonian1944 on May 27, 2020, 08:30:14 AM
Many have asked what happens after the eaglets fledge.  Will we still see them?

After they have fledged (left the nest), they will be in advanced eagle training from their parents.  That includes honing their flying skills, landing techniques, soaring with their parents, learning to hunt for prey and fishing.  At the same time they will continue to depend on their parents for food, often returning to the nest to eat.  Learning to hunt takes time and many misses, so often they will scavenge on carrion.  They will remain close to the nest for a few weeks, but eventually will venture further away and explore other areas. It is thought that by the age of 16 weeks or so, they are pretty self-sufficient and by their 20th week may leave the parents' home range in Sept. or early October.
Title: Re: Bald Eagles Fact of the Day
Post by: pyrmum1 on May 28, 2020, 09:14:06 AM
MEMORY:  The raptor memory is typically very good and aids them in their migration.  Like we humans, the raptors' comprehension and ability to remember is better for sights than for sounds. The raptors' sharpness of vision and ability to recognize things surpasses that of we humans.

Nick Fox, researcher, had a trained goshawk. She would sit quietly on her perch outside in the yard. As soon as she saw a portion of Fox's head appear in the window, she would call to him immediately.   Observations on memory noted are related mainly to trained raptors.  Fox states a trained hawk will recognize its owner after more than a year of separation. It will also recognize and remember the meaning of the lure used as bait as well as the hood the trainers use.
Title: Re: Bald Eagles Fact of the Day
Post by: pyrmum1 on May 29, 2020, 08:48:18 AM
MEMORY CONTINUED:  Fox (researcher) states raptors have a good memory and forget very little.  The capacity for each bird to store information in its memory is an individual event.  As with humans, their comprehension and recollection is far superior for sights than it is for sounds. As predators, their visual acuity and recognition exceeds ours.  Fox further states that hawks recognize places where they have caught prey in the past and will sometimes revisit that area in order to check out the place.  However, with so much land being developed, raptors are finding that what they remember as good places to hunt, are changed & more difficult to recognize.  Fox points out that memory should not be confused with intelligence.
Title: Re: Bald Eagles Fact of the Day
Post by: Bob1603 on May 29, 2020, 10:01:51 PM
We all have heard about the comeback of the American Bald Eagle and here is true story that speaks to that.  It's a fact that the bald eagle is thriving more then ever!

https://www.cnn.com/2020/05/28/us/bald-eagles-massachusetts-scn-trnd/index.html
Title: Re: Bald Eagles Fact of the Day
Post by: glogdog on May 30, 2020, 06:18:05 AM
An adult bald eagle flies (cruising speed) at approximately 30-35 miles per hour and can dive at a speed of up to 100 miles per hour.  Measured flight speeds of migrating eagles were recorded at between 36-44 mph (Broun and Goodwin 1943).  In flight, they can reach an altitude of some 10,000 feet.
Title: Re: Bald Eagles Fact of the Day
Post by: tulsaducati on May 30, 2020, 06:14:55 PM
For May 31, 2020:
At about 8 weeks, eaglets are well feathered and have reached more than 90% of their mature weight. They grow so quickly that a standing eaglet may droop its wings, since the developing wing feathers are blood filled, and their wings can be heavy. Eaglets may practice hovering (sustaining air briefly above the nest) and those all-important landings. Wing flapping and hovering strengthens their pectoral muscles for flying. At this stage, they can be called nestlings, eaglets, and juveniles. Beaks are blue-black, eyes are dark brown, they are more aware of their surroundings, and may react to birds as well as humans nearing the nest.
Title: Re: Bald Eagles Fact of the Day
Post by: Pansie on May 31, 2020, 04:58:13 PM
FOD for June 1, 2020
Eagle Feathers
According to the U.S. Fish and Wildlife, no one other than Native Americans and Alaskan Natives may possess any part of an eagle. Their use of eagle feathers is for religious and cultural purposes. Only a federally recognized tribe may obtain a permit for feathers. The sale to outside entities is prohibited.

According to these cultures, the feather is a powerful symbol that represents honor, trust, wisdom, strength, power and freedom. When a feather falls to earth, it is believed to carry all of the bird's energy, and is a gift from the sky, sea and trees.

While hawk and pheasant feathers may also be used, the eagle feather is held in highest esteem, for the eagle is thought to be the bravest and strongest of all birds. Native American warriors who showed great bravery during battles were gifted with eagle feathers, a symbol of strong medicine representing the highest, bravest and holiest of all feathers.

Eagle feathers are used to adorn the sacred pipe during ceremonies, and if dropped on the ground, a special ceremony is held asking for permission to pick it up, never to be dropped again. To wave an eagle feather over a person's head or a group, signifies blessings, happiness, prosperity and peace.

blog.nativehope. org


Title: Re: Bald Eagles Fact of the Day
Post by: Iriscats on June 01, 2020, 08:04:18 PM
FOD for June 2, 2020

Bergmann's Rule: Applies to many warm-blooded birds and other animals that live in widely
different environments. Large bodies are at an advantage because they lose heat at a slower rate.
Northern bald eagles are so much larger than their southern counterparts that their males are
larger than southern females. In states that are mid-latitude-- and where these 2 subspecies meet
it is very hard to tell the difference between northern and southern varieties because the size
difference is minimal. The smallest known specimens are those from Florida, where an adult
male rarely exceeds 5.1 lbs. The largest are the Alaskan eagles, where a female may exceed 17
lbs and have a wingspan of over 7.9 feet.
Title: Re: Bald Eagles Fact of the Day
Post by: smileawhile on June 02, 2020, 09:20:06 PM
FOD for June 3, 2020

More about developing feathers and fledge:
   It can take up to five weeks after fledge for the flight feathers to be fully grown. Once the wings are completely formed it can still take a week for the blood to retract from the feather shafts, at which time the shafts become firmly attached to the bone.  This is referred to as hard-penned. Until this happens the feathers are more susceptible to damage and can't withstand much vigorous flight.
   So at fledge the eaglets flight feathers are blood-filled (therefore a little heavy) and longer than adult feathers, making for interesting and challenging flight lessons. Take-off is fairly easy but landing demands accuracy and skill. Practice practice practice!

Reference: Dr. Scott Nielsen  A Season with Eagles

https://www.youtube.com/watch?v=DpilgeM5lUk
https://www.youtube.com/watch?v=g56Z4z3v35U


Title: Re: Bald Eagles Fact of the Day
Post by: Bob1603 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! 

Title: Re: Bald Eagles Fact of the Day
Post by: cwellsla 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.
Title: Re: Bald Eagles Fact of the Day
Post by: jfrancl 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

Title: Re: Bald Eagles Fact of the Day
Post by: eaglesrock29 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.   
Title: Re: Bald Eagles Fact of the Day
Post by: tulsaducati 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
Title: Re: Bald Eagles Fact of the Day
Post by: smileawhile 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.
Title: Re: Bald Eagles Fact of the Day
Post by: glogdog 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.
Title: Re: Bald Eagles Fact of the Day
Post by: Pansie 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.



Title: Re: Bald Eagles Fact of the Day
Post by: Iriscats 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
Title: Re: Bald Eagles Fact of the Day
Post by: jfrancl 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
Title: Re: Bald Eagles Fact of the Day
Post by: eaglesrock29 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.
Title: Re: Bald Eagles Fact of the Day
Post by: Faith 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.
Title: Re: Bald Eagles Fact of the Day
Post by: Iriscats 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.

Title: Re: Bald Eagles Fact of the Day
Post by: jfrancl 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

Title: Re: Bald Eagles Fact of the Day
Post by: glogdog 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
Title: Re: Bald Eagles Fact of the Day
Post by: jfrancl on June 20, 2020, 04:21:54 AM
It's been a busy week in Decorah! We ave much to celebrate! All 3 eaglets have branch and so far D34 has fledged!

Today, Saturday, we are holding our annual First to Fledge Fundraiser in honor of D34! Please join us for a day of fun and giving. Without your generous donations, this would not be possible so please help us support RRP's mission and Bob Anderson's dream! Join us here during normal chat hours. https://www.raptorresource.org/birdcams/decorah-eagles/

Title: Re: Bald Eagles Fact of the Day
Post by: eaglesrock29 on June 21, 2020, 02:35:22 PM
D34 and D35 are 11 weeks old today and both have now fledged (D34 at 74 days and D35 at 77 days).  D36 is 74 days old today and looks to be quite ready to go as well, making his or her way around the nest tree with confidence.*

So what can we expect to see as the eaglets are entering their 12th week?  For one thing, we will see much less of them around the nest area, which is sad for eagle watchers and amazing for the eaglets. 

Once fledged, the juveniles will begin to hone their flying skills and landing techniques, and also begin the process of learning to find and kill prey.  They will still depend on their parents for food until they are self-sufficient, which will take at least several weeks.  Their dependency diminishes as they learn to forage.  After fledge, young eagles will chase their parents to claim prey, which may be delivered at the nest or elsewhere.  Look for increased competition and aggressive behavior (good eagle table manners) among the eaglets to claim and steal prey. 

Eaglets typically stay close to the nest tree for several weeks after fledging, but they eventually begin to explore areas further away. 

Their flight feathers are still developing further.  Researcher Scott Nielsen stated that it may take up to five weeks after fledge until their flight feathers are completely formed.  This period is used not only to complete feather growth, but also to develop muscle strength and improve flying skills.

The young eagles will learn and hone their skills by watching their parents, and by practicing instinctive behaviors.

*P.S.  As of the initial writing, D36 had not fledged but has since fledged today as of 6:09 pm, tying sibling D34 and Mom's previous offspring D20, D24 and D28, for earliest Decorah fledge at 74 days. 
Title: Re: Bald Eagles Fact of the Day
Post by: tulsaducati on June 22, 2020, 03:10:15 PM
After the eaglets leave the nest, they will begin to hone their flying skills and landing techniques, and begin the process of learning to find and kill prey.  They will still depend on the parents for food for several weeks.  That dependency will gradually diminish as they learn to forage.  Because fledglings are poor hunters, they will likely scavenge on carrion for a time.   Eaglets typically stay close to the nest tree during the first few weeks after fledging, but they eventually begin to explore areas further away.  Scott Nielsen states that up to five weeks is required from the time the eaglets leave the nest until their flight feathers are completely formed.  This period is used not only to complete feather growth, but also to develop muscle strength and improve flying skills.
Title: Re: Bald Eagles Fact of the Day
Post by: jfrancl on June 23, 2020, 09:34:10 AM
For 6/23/20

From RRP 6/22/2020:

If you are in Decorah, don't chase the eagles and be sure to give them a little room. Chasing is not only illegal, it can harm the eaglets since it interferes with their ability to get food and rest and stresses them out. Acute stress can kill birds. We have a guide to Eagle Etiquette here: https: https://www.raptorresource.org/wordpress/wp-content/uploads/2018/04/BALDEAGLENESTETIQUETTE.pdf

6/23/2020:

Amy went down to Decorah yesterday to take a look around for the eaglets (and tell people not to chase them). Everything was soaking wet and the hatchery was surprisingly empty, but she did manage to find two eaglets! Our camera operators and mods identified them as D34 and D35. These photos are not great - they were taken with a phone, from a distance, so as not to disturb the eaglets - but they give us a glimpse! Our camera operators also found the eaglets: https://youtu.be/odbTKBaIAzg and https://youtu.be/1gUinOGi92Q for two very nice looks!

Brett visited and searched as well. He wrote: "We saw one adult in the maple for hours and found one immature in a snag directly across the creek from the nest. The adult from the maple flew over near the nest and perched (that bird was SOAKED!) and the two talked a bit. We saw no more flights and left shortly after that. We walked the path near the nest and the surrounding areas searching for other fledglings but found none. The rain was coming down steadily. I think it was good that only the adult flew ? not the conditions you want inexperienced fliers in."

Are the eaglets still getting fed? Mom and DM2 delivered three fish just this morning. Everything was so drizzly wet yesterday that the eagles spent most of their time perching and drying off. John and Neil will be at and around the hatchery today, which looks a lot nicer for Outdoor School!


Here is a Time Table for Nesting Bald Eagles and their sensitivity to human activities near the nest that I have saved: https://www.fws.gov/midwest/eagle/permits/baea_nhstry_snstvty.html

Audubon Center for Birds of Prey human activity and disturbances near an active nest: https://cbop.audubon.org/conservation/human-activity-and-disturbances-near-active-bald-eagle-nests

Young fledglings need space to learn all that they need to know to be self sufficient. We can help by abiding by these guidelines when visiting this nest or any other bald eagle nest.



Title: Re: Bald Eagles Fact of the Day
Post by: tulsaducati on June 24, 2020, 02:23:33 PM
First year bald eagles are notorious for attacking just about anything that floats or moves. On average it takes about 4-12 weeks for young eagles to start hunting successfully.  Expert fishing and hunting skills probably take years to develop.  Mark Stalmaster, in The Bald Eagle, explains that approximately 6-10 weeks after fledging, when they are 17-23 weeks old, the young eagles begin to break family ties and leave the nesting area. It is a time to migrate south if their natal nest is up North, or a time to go north if they are raised in the southern latitudes. In some populations that are not migratory, the young may remain in the vicinity of the nest for several years.
Title: Re: Bald Eagles Fact of the Day
Post by: eaglesrock29 on June 25, 2020, 12:15:14 AM
We've talked often in chat about imprinting and there are several previous Facts of the Day that discuss the five parts of imprinting, the last of which is imprinting on nest type, style, and habitat.

Biologist Nick Fox stated that birds will imprint on their immediate surroundings, such as type of nest -- e.g. sticks, rock cavity, ground.  Once the bird is flying, it will imprint on larger aspects of the nest -- e.g. the nest tree, cliff, or man-made structure -- and the surrounding habitat.  In his book, Understanding The Bird of Prey, Fox states "There is a strong correlation between the type of nest in which chicks grow up and the type they will subsequently choose as adults." 

When juveniles leave the nesting territory for the first time, it is thought that they will imprint on land forms such as rivers and cliffs.  This is apparently at least in part how many eagles are able to find their way back to the territory from which they fledged. 

Research shows that female birds tend to disperse further than males.  The tendency for many bird species to return to breed for the first time in the general area of their natal territory is called "fidelity to the nest."   Recent research suggests that males generally begin nesting within 38 miles of their natal nest, while for females, the distance is within 88 miles.
Title: Re: Bald Eagles Fact of the Day
Post by: oregonian1944 on June 26, 2020, 08:34:40 AM
What do we know about bald eagle flight?
They fly at approx. 30-35 mph and can dive up to 100 mph. In flight they can reach an altitude of approx. 10,000 feet.  When they soar, they are riding warm air currents (thermals) and use very little energy to do that.

They have 3 flight patterns: ascending in a thermal, which enables them to soar for several miles before they need to find another thermal; circling downward using a "street of thermals" (series of rising air masses) that results in a single strong thermal; and rising air currents that happen when winds sweep against a cliff or other raised feature of the local terrain.

Title: Re: Bald Eagles Fact of the Day
Post by: jfrancl on June 27, 2020, 04:03:05 PM
Dispersal:

Mark Stalmaster stated that approximately six to ten weeks after fledging young eaglets will begin to break family ties and leave the nesting area.  Dispersal times vary depending on the individual bird, some leaving sooner, some later. By this time they are more or less sufficient, able to fly with ease and acquire prey on their own.  In some populations that are not migratory, they may remain in the vicinity for several years.  And even migratory juveniles may return to the general area of their natal nest location, and perhaps establish a territory of their own and continue the cycle of breeding.  Colder weather increases eagles food requirements and shorter days give them less time to obtain sufficient food. In addition to learning hunting techniques the juvenile will learn what type of prey to hunt and what not to pursue though some prey recognition is obtained while in the nest. First year eagles are notorious for attacking just about anything that floats or moves.  Whether they are successful or not in capturing prey is a different story.  Most first year eagles will feast mainly on carrion or stealing prey from other eagles and other species of birds.

Title: Re: Bald Eagles Fact of the Day
Post by: Iriscats on June 27, 2020, 08:27:48 PM
FOD for June 28,2020

Fishing

Bald eagles use a number of techniques to search for and catch prey.  When a fish is sighted, the eagle will usually descend quickly and smoothly from its perch. The eagle starts at a high angle and has an idea of the location of the fish.  As it gets closer to the fish, it glides in at a bend that becomes steeper until it nears the fish.  At the water's surface, the eagle will reach a foot (or both feet, for a big fish) descend to scoop  up the fish and carry it off. Occasionally when capturing larger fish, the eagle will plunge into the water and may not be able to take flight with its prey.  In such an instance, it will tow the fish ashore swimming awkwardly, stroking the surface of the water with its wings while pulling with its talons to shore.  Another less common technique is wading in shallow water where smaller fish are available.  According to Stalmaster, an eagle will wade up to its belly, submerge its head, and strike with its beak.

Eagles more easily recognize and catch a fish that is upside down (white side up), than right side up(darker side up).  White side up are more quickly spotted and caught. Apparently to eagles' eyes, the white belly is more visible than the darker back.

Bald eagles have a tendency towards species of fish that inhabit shallow water or are surface feeders and therefore vulnerable.  Young eagles are much more likely to "catch" fish that have washed up on shore or fish that are floating rather than swimming.

One study found that when eagles attempt to steal prey from other birds they are successful about 55% of the time.   


Title: Re: Bald Eagles Fact of the Day
Post by: smileawhile on June 28, 2020, 08:28:13 PM
FOD for June 29 2020

It can be a real challenge to ID eagles by plumage from their first through fourth years.
There can be variations in the mottled plumage as a result of:
     incomplete molts
     sunlight fading the feathers
     fading of older feathers
Mark Stalmaster, in 'The Bald Eagle', states that some eagles might skip a plumage class, or retain
one for a longer period, so that many features can be in flux and do not fit any one pattern.
Some researchers think the least pattern variation can be found in the head plumage.
Head color progression (generally):
     1st year - Dark Brown to Brown
     2nd year - Brown to Light Brown
     3rd year - Gray and Light Brown
and by the end of the 3rd year the eagle will sport the "osprey" look of dirty white head with dark
eye stripe.  At this point the tail will also be a dirty white, with possibly a dark terminal band.

While the Decorah nest is inactive or the cameras are shut down for maintenance, I highly recommend that you meander over to the RRP Mississippi Flyway cam (home page - link under 'Watch Birds' tab). You will see eagles of every age hunting, feeding, stealing and interacting with each other.

https://www.raptorresource.org/birdcams/flyway-cam/

https://www.allaboutbirds.org/guide/Bald_Eagle/media-browser


Sources:
    Stalmaster, Mark    The Bald Eagle
    Nielsen, Dr. Scott    A Season with Eagles
    Gerrad/Bortolotti    The Bald Eagle  Haunts and Habitats of a Wilderness Monarch

Title: Re: Bald Eagles Fact of the Day
Post by: glogdog on June 30, 2020, 05:52:21 AM
Tails are integral to bird flight and are comparable to the rudders of ships and boats.  They help birds steer and maneuver while flying, as well as provide stability as they take-off and land.  By twisting its tail, the bird can change its direction mid-flight.  To help the bird slow down, the tail flares out downward, creating more drag and decreasing the bird's velocity.  While the bird is soaring, it can spread out its tail feathers behind it to create additional lift and stability. 

There are 12 tail feathers, formally called rectrices or retrices.  They measure between 11-16 inches in length.  The two center tail feathers are called Deck feathers because they are slightly raised. To minimize flying problems, wing and tail feathers usually molt symmetrically so that matching feathers from the right and left sides fall out at approximately the same time.
Title: Re: Bald Eagles Fact of the Day
Post by: tulsaducati on July 02, 2020, 03:47:11 PM
Dispersal is defined as the purposeful movement away from population centers that serves to separate individual members of avian populations in one area.  Juvenile bald eagles generally leave their natal nest area and begin their adventure when they are no longer dependent on their parents for food.  The results are a mixing of individuals hatched at different locations.  Frank Gill states that large natal dispersal distances can unite populations while small natal dispersal distances may enhance genetic isolation.  Dispersals are often undertaken by recently fledged birds and serve to increase population ranges and reduce population densities so that the birds that disperse are more likely to survive and reproduce than those who do not disperse.
Title: Re: Bald Eagles Fact of the Day
Post by: jfrancl on July 03, 2020, 03:07:50 PM
July 3, 2020


For our final Bald Eagle Fact of the Day post in the forum, I'd like to recommend some birds of prey books for you to read while chat is closed. I hope this makes the time go faster for you and that you enjoy reading them as much as I did.

Hawks, Eagles and Falcons of North America by Paul A. Johnsgard

Majestic Eagles by Stan Tekiela

Raptors the Birds of Prey by Scot Weidensaul

Just Eagles by Alan Hutchinson and Bill Silliker Jr.

How Fast can a Falcon Dive? by Peter Capainolo and Carol A. Butler

A Season with Eagles by Dr. Scott Nielsen

Understanding the Bird of Prey by Nick Fox

The Bald Eagle by Mark Slalmaster

The Bald Eagle Haunts and Habits of a Wilderness Monarch by Jon M. Girrard snd Gary R. Bortolotti