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SOAR’s Frequently Asked Questions

These are compiled from email and public and school programs. Have a question about raptors? Email us!

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Raptor Biology

Raptors are top predators and are indicators of environmental health.

How long does it take raptor eggs to hatch?

  • Incubation time varies with the size of the bird. Owls, hawks, and falcons may incubate 26-37 days while eagles may incubate 34-40 days. The first egg laid hatches first and the second egg hatches about two-four days later. If there is a third egg hatches, it will hatch two-four days after the second. Smaller species tend to lay more eggs than a larger species.

What are the stages of bird of prey development?

  • During the first few weeks after hatching, eaglets and other raptors are almost never left alone. Parents keep very busy taking care of them. One parent is always on the nest covering their babies with wings to keep them warm and to protect them from sun and weather. As the nestlings gain strength, they begin to wobble on their feet using wings like crutches. They are very clumsy. As they become bigger and stronger, they are much more steady and flap their wings and begin to “branch.” Branchers test their skills by going to nearby branches and stay close to the nest. First flight usually occurs around 75 days after hatching (for an eagle) and the bird is then a fledgling. Young birds have different ‘feed me’ calls at the different stages of development. If a nestling becomes displaced from the nest and is on the ground like a brancher or a fledgling might and gives the ‘feed me’ call, the adults don’t recognize that as being correct and will not feed. A brancher / fledgling on the ground makes a different feed me sound and the parents will bring food to that youngster. It is very important to do what is safely possible to re-nest young birds with their parents.

What is special about raptor feet?

  • Raptor feet are amazing. Eagles, falcons, and most hawks do not have feathers that cover their feet. Owls have fine, specialized feathers to cover their feet. The size, thickness, and curvature of the talons are matched to the bird’s hunting habits. Small falcons, like the American kestrel, have long and slender toes designed for perching and grasping and their talons are curved and needle-sharp. Ospreys have toes that are covered with spicules on the underneath side (like a Velcro feeling) to grasp slippery fish. Their outer toe is reversible, just like an owl’s, and their toes are tipped with long curved talons (fish hook style) that are sharp as needles. Eagle’s toes are short and powerful with long, strongly curved talons.

Can an owl turn its head all the way around?

  • Owls can turn their head 270 degrees, that is about twice what you and I can do! They can do this because they have more vertebrae in their neck than humans.
  • How do owls spin their heads without tearing arteries? Read this NPR story about and check out the visuals for this college students science investigation.

What materials do Iowa eagles use in their nest?

  • The main things you see in an eagle nest are sticks! Some will bring back sticks that they find while soaring and hunting for their food. Sometimes, they steal sticks from beaver dams. Beaver dams have lots of sticks to choose from and it’s easier to let someone else do the hard work of finding and shortening sticks! You will see mud, grass, cornstalks, and corn husks woven in with the sticks. The bowl of the nest is usually lined with soft grass and plant materials. Eagles are always working to make their nest better and keep a clean house.

Do all raptors migrate and where do they go?

  • In some species, like osprey, broad-winged hawks, and peregrine falcons, almost all of them migrate out of the US and Canada to Central and South America.
  • In some species, only some individuals migrate and the distance varies depending on food availability. A lack of food is the biggest reason that most hawks leave their breeding territory in the winter.

What do you call the path that birds use to migrate?

  • A flyway is the path that birds congregate along to travel. There are four major flyways in the US: Pacific Flyway, Central Flyway, Mississippi Flyway, and Atlantic Flyway.

What types of migration patterns are there?

  • Neotropical migrants are birds that breed in North America, but spend the winter season south of the border in Mexico, Central America, South America, and the Caribbean. Some older folk may still call them “jungle birds.” A few examples would be blue-winged teal, oriole, tanagers, bobolink, grosbeaks, hummingbirds, Swainson’s hawk and osprey.
  • Short-distance migrants are birds that winter south of their breeding grounds, but stay mainly within the United States and Mexico. Wrens, killdeer, red-tailed hawks, bald eagles, and white pelicans are examples.
  • Partial Migration is considered by some to be linked more to a “genetic code.” Some birds of the same specie will migrate while others will stay in the same area. Iowa examples include robins, bluebirds, goldfinches, chickadees, etc. Some will migrate, while others tend to stay and bear our winters deeper into wooded protection. Iowa holds many flocks of robins all winter long, but come spring, large flocks of returning robins appear in our yards again returning from somewhere south.
  • Irruptions are usually a result of a food-driven journey. Food sources of some birds can vary dramatically, season to season, year to year. Some would call this a “flexible” migration strategy. An example would be the snowy and saw-whet owls and other boreal birds that follow their significant food source. 2012 was considered an irruption year with the dramatic migration of young snowy owls moved into Iowa and even Missouri. Our environment here does not compare to their homeland in the tundra and many of those birds face huge mortality.

A raptors hunting style is based on wing shape.

  • All falcons have long jet fighter wings that allow the larger falcons to fly swiftly and to stoop (dive) at great speeds. Smaller falcons like the kestrel may not fly as swiftly, but for their size still have powerful wing beats. The raptors that soar have broad wings. Look at the wings of eagles, red-tailed hawks, and vultures and see the large surface area that allows them to ride the thermals. Accipiters that prey on other birds and live among trees and now in towns have short, broad, round-tipped wings for agile and quick turning flight. Owl feathers have fuzzy edges that disperse the wind and help them fly silently in the night while hunting.

Are those satellite dishes?

  • Those raptors that utilize hearing, particularly those that hunt at night or dawn and dusk, have facial disks of feathers that help funnel sound in the ear canal. Owls have the best hearing of the raptors, but harriers also have facial disks and have good hearing.

Do daytime (diurnal) raptors use eyesight or hearing more for hunting?

  • Birds of prey have the most developed eyesight of all animals. Their eyes are placed on the front of their heads and like us have overlapping binocular vision. Raptor eyes are very large in proportion to the size of their head. As a visual, it’s been described that for a human to see as good as an owl, our eyes would need to be the size of tennis balls. Because the eyes take up so much room in the skull, there is not room for the musculature needed to move the eyeball, so the eyes are fixed and to help determine depth perception and distance, you will see a raptor bob its head or move side-to-side.

Can raptors smell?

  • Most birds do not detect airborne scents. Vultures may be the only raptor with a well-developed sense of smell.

Raptor Trivia

Eagle factoids from USFWS Midwest Region

  • The bald eagle is truly an all-American bird; it is the only eagle unique to North America.
  • Nests are sometimes used year after year and can weigh as much as 4,000 pounds.
  • Bald eagles may live 30 years in the wild (even longer in captivity).
  • Bald eagles pair for life, but if one dies, the survivor will accept a new mate.
  • In hot climates, like Louisiana and Florida, bald eagles nest during winter.
  • Bald eagles get their distinctive white head and tail only after they reach maturity at 4 to 5 years of age. (SOAR has noticed that it may take until the eagle is 8 years before the entire head is a brilliant white. Just like people may have a color streak in their hair, some eagles don’t ever seem to get an entirely white head of feathers.)

How many feathers does a bald eagle have?

  • Bald Eagles have approximately 7,000 feathers. Feathers, like hair and nails, are made of keratin. Feathers are made of interlocking, microscopic barbules that are light, but very strong. Layers of feathers trap air to insulate birds against cold and protect them from rain.

Terms and Terminology

This is not a complete glossary of falconry, birding, and research terms used today, but many are terms used at SOAR and may be heard during a SOAR event or used on the website or our Facebook page content. Yes, sometimes one word can have more than one meaning, depending on context.

Accipiter

  • The Latin name for a genus of raptors; short, rounded wing shaped hawks, long tail, built for speed and maneuverability through woodland habitats, such as sharp-shinned hawk and Cooper’s hawk.

Bate

  • An attempt to fly when secured to a fist or perch.

falcon on blockBlock

  • A block of wood covered with turf, with a heavy base or a spike to push into the ground, used as a perch for falcons. Photo by KM Bossard.

Bracelet

  • A leather strap fastened around the leg of a raptor, through which a jess is threaded. Jesses – Leather straps or braided cord fed through the grommet of the bracelet. Leash – A detachable braided cord attached to the jesses by a swivel with which a trained bird is tied to its block, perch, or glove.

labeled anklets, jesses

 

 

 

 

 

 

 

Brancher

  • A young raptor that has lost their down, is mostly feathered, has left the nest but has not gone far and still relies on adults to bring food.

Buteo

  • The Latin name for a genus of raptors; “broad-winged” hawks, such as the red-tailed hawk, rough-legged hawk, etc.

Thora on bow perchBow perch

  • Semi-circular metal perch, both heavy and free-standing or pushed into the ground, where a raptor can be secured.  The bow where the bird perches is wrapped with rope. Bow perches come in many sizes. Thora sits on a bow perch.

Cast

  • (1) The act of regurgitating fur, feathers and/or bones that cannot by digested or (2) To hold or wrap a raptor to prevent movement.

Casting

  • The indigestible portions of the last meal of a raptor, usually bones and feathers that are formed into a compact pellet and disgorged through the mouth. See Pellet.

Cope

  • Cutting back or shortening either beak or talons of a raptor.

Crop

  • (1) The vascular sac above the sternum in which the diurnal raptors first receive and store food before passing it on to the stomach. It is not present in owls. or (2) The amount of food a raptor is permitted to take; as a half-crop, a full crop, etc.

Crop, turn over

  • The action of a raptor, when movements of the neck and shoulders forces food from the crop into the stomach.

Deck(s) or deck feathers

  • The two central tail feathers.

Eyass, Eyas, or Eyess

  • The young of raptors while they are still in the nest.

Eyrie, Aerie

  • The nest or nesting ledge of any of the raptors.

Falcon

  • Originally referred to the female of the “long winged” hawks (genus Falco); now applied to any species and either sex of the genus, such as American kestrel, peregrine.

Feak

  • The action of a raptor of wiping the beak against the perch, glove, or tree branch after feeding.

Fledgling

  • Fully feathered, starting to fly and still relies on adults to bring food. Eventually will start making attempts to hunt on own and will do so with increasing success.

Foot

  • To clutch or hold prey; also dexterous use of the feet.

Frounce

  • A disease of the mouth and throat.

Hack

  • A passive release; leaving a bird free for a time to develop flying skills.

a hooded falconHood

  • A close-fitting leather cap used to cover the head and eyes of a diurnal raptor (hawk, falcon, or eagle).
  • Braces – The leather straps (made like a leather jess) are used to open or close a hood. Pull the long ends to close and the knotted ends to open.
    falconry hood

 

 

 

 

 

HY

  • HY means hatch year or a bird born that calendar year. Sometimes we are specific to a year and may say HY15 or HY14 to indicate which year the bird was hatched.

Imp or Imping

  • A method of repairing broken feathers.

Imprinting

  • Refers to a critical period of time early in an animal’s life when it forms attachments and develops a concept of its own identity; can occur in the first few hours or first few days depending on species. Imprinting is a wonderful example of the interaction of innate, species-specific behavior, and the properties of a special kind of learning, which has been called “perceptual learning” (Bateson, 1966). These studies maintained that animal species are genetically constructed to enable them to learn specific types of behavior that are important for the survival of their species. Imprinting is one of these forms of behavior.

Juvenile

  • An independent bird that does not yet have adult feathers / plumage.

Kettle

  • A group of raptors that are circling in the air staging for migration.

Lead level test, blood lead level (often seen written as BLL)

  • Test results can be expressed in parts-per-million (ppm) or micrograms per deciliter (µg/dL). For reference, 10 µg/dL = 0.1 ppm. Blood lead level tests can only be done on live patients. Once dead, a liver tissue sample is used if a lead level is needed for research.

Man or manning

  • The process of conditioning raptors for handling.

Mantle

  • The stretching of one wing and one leg on the same side. It is an indication of a relaxed and contented bird. Mantle over – The spreading of wings and tail over food or quarry.

Mews

  • The building or room in which raptors are kept.

Mutes

  • The excrement of a raptor.

Nestling (or hatchling)

  • Rely 100% on parents to feed them, will still be covered in down, some feather growth. A raptor this age cannot tear their food. If a nestling is no longer in the nest… it likely will not get fed.

Nocturnal

  • The term ‘nocturnal’ means a night time animal and ‘diurnal’ means a daytime animal. Have you heard the term ‘crepuscular?’ Crepuscular animals are active during dawn and dusk.

owl pelletsPellet

  • A pellet is accumulated undigested material, in the case of eagles and hawks they are primarily hair. An owl pellet contains bones of the animals they have eaten; this is because an owl has less stomach ‘juices’ to digest the bone.

Preen

  • Straightening and grooming the feathers; one of the signs of contentment and good adjustment of a trained raptor.

Raptor or bird or prey

  • The word raptor comes from the Latin rapere and means “to seize.” A bird of prey is a bird that eats another animal. The terms may technically mean different things, but both terms describe the same group of birds. These birds have talons to seize or take their prey.

Rouse

  • An action common to all birds in which all the feathers are slowly erected, the bird shakes itself, and the feathers then slowly settle back into place.

Soar

  • The riding of thermals (currents of heated, rising air) or updrafts by a bird.

Stoop

  • A rapid descent from altitude, usually in pursuit of quarry.

Tiercel or tercel

  • The male of any of the raptors used in falconry.

Weather

  • Placing a raptor in the open air in good weather, secured to a block or bow perch.

Our Education Birds

Have Spirit and Liberty ever been foster parents?

  • The answer was no up until the spring of 2012. A spring storm took down an eagle nest in Dolliver State Park, near Fort Dodge, Iowa. A hiker came across the downed nest and eaglets, hiked out to find park staff, who hiked back in to rescue the one live eaglet. The eaglet was brought to SOAR. After an exam and a couple meals, the eaglet was placed in Spirit and Liberty’s enclosure and monitored discreetly. The new parents tended to this eaglet instantly. The young eagle was released at the end of June 2012.

Would or can Spirit and Liberty nest and have young of their own?

  • While both eagles are sexually mature and by all rights ‘could’ build a nest, breed, and hatch eggs… Liberty and Spirit are on what is called an eagle education permit from the U.S. Fish and Wildlife Service which means these two are to be used only for education. Let’s hope they’ve read the permit and the federal regs so that they don’t try anything behind our backs!! 🙂 Besides we have not seen any eagle-courtship behavior and would assume that the two don’t find their accommodations suitable for nesting. Liberty has limited flight capabilities and doubt he could successfully mount / mate with Spirit. We have noticed the last few years that Spirit gets grouchy in the late winter and spring.

Other

When did the bald eagle become our national symbol and why?

  • On 20 June 1782 our Continental Congress (as it was called then) selected the bald eagle as our national symbol because of the bird’s symbolic power, strength, and freedom. Yes, Thomas Jefferson did suggest the wild turkey be the national symbol.

Are raptors protected by any laws?

  • The Migratory Bird Treaty Act of 1918 – protects migratory birds and any part, nest, or egg of any such bird, except as allowed for by specific law (like duck and goose hunting)
  • Lacy Act Amendments of 1981 – updated the Lacey Act of 1900 and protects bald eagles by making it a Federal offense to take, possess, transport, sell, import, or export their nests, eggs and parts that are taken in violation of any state, tribal or U.S. law.

Do eagles have additional protections?

Want to learn more about eagle species from around the world?

  • Check out the Eagle Directory! The Eagle Directory is dedicated to providing accurate information about eagles from around the world!

Habitat

Are red-tailed hawks to blame for low pheasant numbers?

  • It’s all about habitat — both quantity and quality.
  • Weather impacts upland game populations from year to year — after a severe winter followed by a wet spring, the conditions are not optimal for successful nesting. According to the 2011 Iowa DNR August Roadside Survey, “This marks the 5th consecutive winter in a row Iowa has received ~ 30 inches or more of snowfall. In the 50 yrs of standardized roadside counts Iowa has never seen 5 consecutive winters of this severity.” Click here for the complete DNR August 2012 Roadside Survey.
  • Habitat loss is gradual and is best noted over time. US Department of Agriculture estimates that over 2,400 square miles of small grains, hay ground, and CRP has been converted to soybeans and corn between 1990 and 2005.
  • Besides, did you know that 75% of red-tailed hawk’s diet is made up of small mammals like rabbits, mice, rats, and ground squirrels?
  • Check out Protected Predators Keep the Balance