Bald Eagle Facts | Characteristics of bald eagles (2023)

Q: How big is a bald eagle?
A:About 30 inches.

Q. How many feathers does the average adult eagle have?
A.7.200.

Q. How slow can an eagle fly and still stay aloft?
A.Very slowly; Think of an eagle just taking off. The slower they fly, the more flaps they have to flap their wings to stay aloft, and the more energy they burn.

Q. How fast can a bald eagle fly at top speed?
A.The average flight/gliding speed is 50 kilometers/hour; The normal flying speed from perch to perch is much lower.

Q. What is the exact wingspan of an adult bald eagle?
A.Northern eagles range from 200 to 235 centimeters (6 to 7 ft); Their southern eagles are slightly smaller in all sizes (weight, wingspan, etc.). One of the largest wingspans of all time comes from a bird with a wingspan of 243 cm - 7.9 feet!

Q. What kind of feet do bald eagles have?
A.Scaled (featherless) feet with 4 toes, each with a very severe claw (claw). Three toes point forward, with a fourth (the hallux) pointing backward to help grasp prey.

Q. How big is an eagle's brain?
A.It's quite small, about an inch or so cube.

Q. How many species of eagle are there?
A.There are 59 species worldwide.

Q. Can eagles turn their heads completely like owls?
A.No, but they have considerable movement.

Q. How good is your night and day vision?
A.Not great at night and about 3-4 times better than humans during the day.

Q.Are bald eagles strong enough to kidnap babies and young children?
A.No. This is a fairy tale! They can only carry a few kilos at most.

Q. Can an eagle sweat?
A.No. They "thermoregulate" (control their temperature) by panting with their mouths open or by losing heat through their bare legs and feet.

Q. How do the feathers stick to the bird?When I find a feather on the ground it seems to have no roots.
A.Feathers, like the scales on the feet or the claws or the horny sheath of the beak are keratin-like outgrowths of the skin, similar to our nails. Feathers grow from skin follicles, just like human hair. The skin holds the feather cone to the follicle, and tiny tufts of "feather" muscles in the skin at that location and between the follicles hold the feathers and cause their movement. If you've ever tried to pull feathers out of a bird, particularly a large wing or tail feather, you know how tightly they are held in the skin that surrounds and overgrows the shaft.

Q. Do bald eagles play?
A.Great question! With wild animals, it is often difficult to determine the reasons for behaviors that we may observe. I believe eagles enjoy certain activities that could be termed play, e.g. when chasing each other in flight, swooping, rolling, etc. As with humans, I think immature bald eagles are more prone to "game". as adult birds who always seem to have something to do on purpose :)

Q. What is the difference between a bald eagle and a golden eagle?
A.The main difference is that bald eagles belong to a group of "sea eagles" that live in or near bodies of water and are piscivorous (fish eaters). Golden eagles belong to an entirely different group of eagles known as true or "booted" (legs with feathers versus scales) eagles, and are highland eagles, meaning they don't go near water. They mainly hunt upland mammals versus fish. These are just two of about 59 species of eagles worldwide, but the only two we have here in North America (with the exception of another species that appears occasionally in far southwest Alaska). The bald eagle gets its name from the Old English word balde, meaning white-headed (not hairless!). "Golden eagles" probably get their name from the top and back of the head and nape, which are a beautiful golden color.

Q. Do you think eagles are afraid of humans?
A.I think their natural instincts tell them to be careful and stay away from people.Q. Is there an important reason why bald eagles have yellow eyes?
A.Great question. I really don't know if there's a reason the adult iris is light, other than that it's a morphological difference from the immature birds, which have darker, brown irises until sexual maturity. Could the yellow eyes look more menacing?

Q. Does a female bald eagle have a white head like a male?
A.Yes, they look identical. The female is larger than the male, however, and measurements of certain body parts such as the beak and rear claw (hallux claw) can distinguish the two sexes. otherwise you can't tell.

Q. How does an eagle see an animal on the ground while soaring high above it?
A.You have extremely sharp vision. Your eyes are specially designed for long-distance focus and clarity. The eye is large with a large retinal surface area with a high concentration of cones (all our eyes have rods and cones that allow us to see) that help with visual acuity and color perception, among other things. It has been estimated that eagles can see three to four times further than humans and that they can see another eagle soaring nearly 50 miles away.

Q. What is the diving speed of the bald eagle?
A.Pretty quick when they do, I'd bet 75+mph, although they rarely really "dive". .

Q. Can a bald eagle swim?
A.Great question. Absolutely. They are very good swimmers and I have even seen older nestlings who cannot swim yet. It's not uncommon for an eagle to "misjudge" a fish and latch on to a fish that is too heavy/big to fly with, possibly swimming quite a distance to shore (wouldn't up now want to skip lunch, or) drag the fish to shore and then eat it.

Q. How fast and how far can a bald eagle fly if it flies for 30 minutes?
A.That depends on what the eagle is doing. If it's just flying from one feeding ground to another, or from its nest to the end of the lake, it's probably flying around 20-30 miles per hour. When migrating, eagles rarely flap their wings; Rather, they use thermal updrafts to gain great altitude and the saor in a long, descending glide in which they can easily reach 50-75 mph.

Q: Why are the heads of adult eagles white?
A:That's a great and logical question! Although no one knows the answer for sure (not scientifically proven), below are some hypotheses:

• for visibility to make it easy to locate and identify other individuals of the species
• to denote sexual maturity in contrast to immature eagles, which lack the white head
• to indicate dominance, like top dog

Q: How can you distinguish between adult male and female bald eagles?
A:Visually, they look identical, but as with most raptors, the female is larger (heavier and taller) than the male. Sometimes this is clearly visible in a pair if you see them together at the nest, but other than that we're just guessing. In the hand, biologists can tell males and females apart by using two important measurements of body size, the depth of the beak (beak) and the length of the hallux claw on the back toe. These measurements are fitted into a clean formula developed by eagle biologist Gary Bortolotti in the early 1980's based on numerous measurements of eagles of known sex.

Q. How can you tell if the bald eagle is male or female?
A. As with all birds where the sexes do not have distinct plumage, the only way to tell differences in sex is to look throughsize dimorphism(size differences) or during an internal examination called a laparoscopy. Bald eagles exhibit size dimorphism; Females average about 1/3 larger than males. Data compiled by Mark Stalmaster (1987 - "The Bald Eagle", p. 16) found that two measurements of size, beak depth and hallux (toe claw) length, show the largest segregation between the sexes. These measurements can be used in the following equation: Sex = (Beak Depth x 0.392) + (Hallux Length x 0.340) -27.694 (measurements are in millimeters). If the answer is affirmative, the eagle is a female. If the answer is negative, the eagle is a male. See if you can figure out the sex of this eagle - it's one of the 4 birds we're tracking in the western study: beak depth = 34.5mm; Hallux length = 43.0 mm.

Practically, I can guess the sex of most birds when on the bait and in hand just by general size differences. Birds in the overlapping area of ​​the measurements are more uncertain; a subjective route to sex is temperament; Females are docile and will not bite or squirm... Males are very aggressive in hand. I also sex the birds before catching by listening to their calls - the males' whistling calls are almost a screech, the females' are much deeper.

Q. Do eagles molt annually or how often do they shed their feathers?
I've seen references that say they don't molt annually. All chicks grow early feathers that last throughout their adolescence. They molt into adult plumage after breeding, and according to Coles BH (Avian Medicine and Surgery. Blackwell Scientific Publications, 1985), large birds of adulthood, such as eagles, molt every two years. Another reference states that all adult birds molt annually in a gradual process during spring, summer, and fall, while flight feathers molt only in July, August, and September. This claim is not substantiated. What is the truth?
A.Believe it or not, this question is not easy to answer; Despite all the years and people studying eagles, the molting process is still not well understood. Before reaching sexual maturity around 5 years of age, we have to think about moulting in relation to different plumages.

Young eagles go through four different plumages until they reach sexual maturity,adult plumage, that would be the fifth plumage type. These are (as described by Clark and Wheeler in Hawks of North America):
youthful, white bellyI,white belly II, Andtransition to adulthoodPlumage.

So you might think, ok, 5 years to sexual maturity, 5 plumage, one molt per year, right? Not exactly. Moult can be influenced by a variety of biological and species-appropriate factors (such as food availability, densities of other eagles, and others), and not all moults are always complete moults.

Once they have reached their final "adult" plumage, bald eagles are likely to shed their flight feathers nearly every year, primarily in New York from summer through fall. However, some signs of molting can be seen at almost any time of the year.
This flight feather moult is not simultaneous; Rather, matching flight feathers are generally lost at different times, so the birds are never left flightless.

Q. How many muscles do eagles have?
A.A very interesting question that sent me to the books! I haven't found any specific reference to bald eagles, but the Audubon Encyclopedia of North American Birds says that 175 different muscles, most of which are paired, have been described in birds. The number in eagles is probably close. The legs alone contain about 35. Muscles make up between 35 and 60 percent of the total mass (weight) of birds.

Q: How much can a bald eagle lift?
A:Bald eagles generally weigh between 4 and 6 kilograms, although a few have been found both below and above this range, with some Alaskan eagles having been recorded weighing well over 7 kg. Female eagles are the larger and heavier of the sexes. Now that we know how much eagles themselves can weigh, we can use that to define how much they can lift. Of many prey found and weighed in nests, a good general rule seems to be that eagles can carry up to half their own weight. This obviously means that female eagles are capable of carrying larger prey than the males. Eagles sometimes have trouble judging the weight of their prey. I have seen eagles in Alaska "hanging" a large salmon, obviously heavier than it could be carried away in flight, and the eagle is very capable of hovering with its prey and "swimming" ashore , instead of giving up. Then, pulled ashore, the feasting begins.

Q. How can eagles see the fish underwater?
A.Eagles have very good eyesight, 3-4 times better than you or me. You can see fish from a great distance, even far down in the water. Most of the time, however, the osprey catches very close to the surface of the water.

Q: I've noticed in several books of photographs of bald eagles that their eye color can vary. I've seen blue, yellow and brown. Why?
A:In general, eagle eyes are fairly uniform in color. Nestling eagle eyes are almost black. Young eagles (first-year birds just out of the nest) have brown eyes (which can vary in lightness or darkness, but are usually quite dark).
When they become immature eagles (age 2.3), their eye lightens to a light brown. As they approach sexual maturity (age 4.5), their eye turns yellow and again can be various shades of lighter to darker yellow, but usually quite pale yellow. I believe that the darker eye color of juveniles and hatchlings may be a defense mechanism not seen as a threat that yellow adult eyes could be. Similar coloration and a gradual color shift to lighter and lighter are found in the beaks of bald eagles with age. I've never seen blue eyes on eagles!

Q: Do eagles see in color or black and white?
A:Great question! Everyone knows that bald eagles have excellent eyesight. We believe that depending on the number, they can see in colorconesin their retina. It is well known that cones are necessary for visual acuity and color vision, unlike theThe rodseen in low light, something eagles are not particularly well adapted to.

Q: Do eagles see black or white or colored? Doesn't she like the color red?
A:I knew I had seen a very thorough treatment of eyes and vision somewhere, so below is what I found on thatwebsite: “All eagles are known for their excellent eyesight and the bald eagle is no exception. They have two foveae, or centers of focus, which allow the birds to see forward and sideways at the same time. Bald Eagles are able to see fish from several hundred feet in the water while hovering, gliding or flapping is quite an extraordinary feat as most fish are countershaded meaning they are darker on top and therefore heavier from above Fishermen can attest to the difficulty of spotting a fish just below the water's surface at close range. Juvenile bald eagles have been known to make mistakes, such as attacking objects such as plastic bottles that float at or just below the surface of the water. Bald eagles locate and catch dead fish much faster and more efficiently than live fish because dead fish swim up with their light colored underside making them easier to see. Eagles have eyelids that close when they sleep. They also have an inner eyelid called the nictitating membrane for blinking. Every three to four seconds, the nictitating membrane slides back and forth across the eye, wiping dirt and dust off the cornea. Since the membrane is translucent, the eagle can see even when it is above the eye. Like all birds, eagles have color vision. An eagle's eye is almost as large as a human's, but its sharpness is at least four times that of a human with perfect vision. The eagle can probably identify a rabbit moving nearly a mile away. This means that an eagle flying at an altitude of 1000 feet over open country can spot prey over an area of ​​nearly 3 square miles from a fixed position."

Q: How long are the talons of a bald eagle?
A:Eagles have 4 claws (and toes) on each foot, a hallux claw on the back of the foot pointing forward and 3 toes on the front of the foot where the claws point backwards. The hallux claw is always longer than the other normal claws. And in females, this claw is longer than in males. In fact, since females are longer than males, this is one way of determining the sex of bald eagles by measuring the hallux claw. These hallux claws are nearly 2 inches long in large, female eagles and only about 1.5 inches in small males.

Q: Are claws the same material as human fingernails?
A:Yes, and they are very similar to a dog's claws.

Q: Are the claws strong?
A:The actual power comes from the muscles in the legs which, when contracted, pinch down the tendons in the lower legs and toes, locking all the claws together in a vise-like grip. I remember that hold well once I was fully on my feet by an eagle we had caught; it took two of us to pry the toes apart and pull out the claws.

Q. Do bald eagles have the same digestive system as humans?
A.Now there is an interesting question! The answer is no. Birds generally have a higher metabolic rate than us, which requires them to process their food as quickly as possible. That means getting them into a form from which they can extract the energy they need quickly and efficiently. Birds, including eagles, have adaptations for this. Most importantly, part of their stomach has turned into a gizzard, which we don't have, in which food is broken down to a fine consistency to allow for quick digestion. In eagles, this is also where pellets are formed. These are masses of indigestible prey material such as fur, feathers, and occasionally bones, which then travel backwards from the gizzard to the mouth and are expelled (like vomit) from the mouth. Depending on the food intake, pellets are formed overnight after the meal, which are usually ejected the next morning. Most fish are fully digested. Eagles have very strong stomach acids and are quite good at digesting bones, which helps them with their own bone formation and eggshell formation. Another big difference is that eagles (and other birds) have something called a goiter in their upper esophagus (gullet), where food can be stored for days. This is extremely beneficial for eagles, which can store up to two pounds of food in their crop when prey is plentiful, allowing them to go several days without food if necessary. There are more differences, but these are two of the most important.

Q. Do eagles sing?
Last August, while canoeing on Oregon's Upper Klamath Lake, we saw an adult bald eagle coaxing an adolescent into flying. Finally the young eagle flew out of the nest. When the adult returned, after circling a few times and followed closely by the younger bird, one of them broke into song. We've never read anything about singing eagles (besides their normal screeching). Is this common or a coincidence of nature?
A.Lucky to be up on Klamath Lake! Adults persuade their young to leave the nest just as you have observed. Eagles vocalize regularly. They have few types of vocalizations, and virtually nothing is really known about their meaning (although many suspect them). A lot of people also talk disrespectfully about the "rootiness" of eagle calls, but I guess it depends on your perspective. I found their primary call, which I describe as a descending chirp, laughter-like call, quite sinister and piercing. I don't know what they're trying to say, but they use that call in many different circumstances, and the one you describe doesn't surprise me in the least. They often use this call when other eagles are present or flying in, say to a feeding or roosting spot or a perch. It could be a warning, or a greeting, right? One of the things I would like to know one day is what eagles say to each other!

Q: Do the eagles have a special breathing technique when flying so high?
A:Good question! This sent me to the books on bird physiology myself! In reality, eagles typically expend very little energy flying that high. Although they can reach altitudes in excess of 10,000 feet, they typically climb to these altitudes and take long glides to cover the ground, then climb back up and repeat the process. By flying this way, their bodies really don't need much oxygen, not nearly as much as when they are much closer to the ground and expend a lot of energy flapping their wings. So, no, they don't have any special adaptations for breathing at high altitudes.

Q: Does an eagle fly aerodynamically like an airplane?
A:All birds share the aerodynamics of airplanes (actually, they're airplanes that "learned" their aerodynamic lessons from birds!). Bird wings are designed to gain lift from pressure differences as air moves above and below the wing. (See "Bernoulli's Principle of Flight".)Birds, including eagles, also have hollow (but very strong) bones to reduce overall body weight and aid in flight. However, unlike many other birds, eagles are fairly heavy, bulky birds. Because of this, they need a lot of space and a lot of energy to take off, similar to an airplane. They are not birds designed for fast flight and maneuvers. Rather, they really shine as soaring birds, using their large wings, once in the air, to harness air currents and natural thermals to soar at great heights and great distances with almost no effort.

Peter E. Nye
New York State Environmental Protection Agency
Department of Fish, Wildlife and Marine Resources
Albany, New York

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