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Raptors

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The Peregrines

The NH Chapter of Audobon Society reports record-high levels of peregrine nesting in 2001.  The group installed and maintained a nest box on New Hampshire Tower, an office building in Manchester, and were rewarded with four fledged young.

We love tracking the Peregrine Cam at the Rachel Carson Building in Harrisburg, PA.  (See Wildlife Page for link.) The native breeding population of peregrines, estimated at 350 nesting pairs in the early 1900's, in the eastern U.S. were extinct by the mid-60's, largely due to the effects of DDT.  A new population was reintroduced by The Peregrine Fund from captive-bred birds.  The largest concentration in the East is along the cliffs, bridges, and buildings of the Hudson River.  Washington D.C. (a church tower in midtown) was the site of a nesting pair in the late 1990's.

The Eagles

American Bald Eagles are unique to North America.  Only 50% of the eagles hatched survive beyond one year.  The white head and tail feathers do not appear until they are about 4 years old.  Their population south of Canada fell from about 100,000 birds in the 1700's to 417 nesting pairs by 1963.  Following passage of environmental laws in the 1970's,  the population is estimated to have risen to 20,000 birds in the lower 48 states and 35,000 in Alaska. 

New Hampshire has five known nesting areas, but has had only one successful nest or more than 2 young produced in any year since 1940.  A  nest was recently discovered in the line of a proposed airport expansion in Manchester.  Environmentalists are opposing the expansion.   (Source:  New Hampshire Audubon   Society, Chris Martin, Audubon Senior Biologist)  The photos below were taken at a cam site on the Connecticut River at the Silvio Conte Wildlife Refuge.

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Source:  Oregon Fish & Wildlife Service.  One of the best sites for info on raptors.  See online address below.

Raptors provide a clear look at the connection between birds of today and ancient reptiles, including dinosaurs. These birds have light, strong bones and long, powerful muscles. Like those reptiles, raptor eyeballs are designed for quick movement and rapid changes of focus. Both raptors and many reptiles have a nictitating membrane or third eyelid which blinks across from the innermost corner to protect the eye from dirt and the struggles of prey.


Raptors, like predator species in all animal groups, have their eyes set much further forward than those of prey species, who must worry more about what is closing in from behind to eat them. In addition to incredibly sharp eyes, which are designed to focus at long distance and notice slight movements, raptors have acute hearing.


This bird group tends to be monogamous and will return to nest in the same area year after year. Some, like the bald eagle, will return to the same nest,
adding to it until its great weight might bring down the supporting tree crashing down. One bald eagle nest weighed more than 2,000 pounds when it fell with its tree after more than 36 years of use.


Raptors help the environment by eating rodents and keeping their numbers under control. In fact, hawks and owls overlap their coverage of an area, so that both the diurnal hawks and the nocturnal owls maintain constant pressure. Too often, the decline of raptors and other predators has led to tremendous ups and downs in small mammal populations, as they reproduce without restraint until disease or starvation wipes them out. This is referred to as the boom-bust cycle.


Generally, the larger the bird, the more territory it needs to provide food and shelter for its young. Most raptors have definite hunting areas which are marked by sound and sight. The immediate area around the nest is defended; the hunting area is usually not.

Management
Raptors management takes many forms. One important aspect is a program of public education to let people know just how important raptors are to the environment. Second, a damage control program is underway to help reduce the loss of domestic animals and birds to raptors. Various means are used in this effort, including overhead fencing and nonlethal forms of harassment. It is against federal law to kill any hawk, eagle or owl.


Another type of raptor management involves the attempt to improve reproduction, nesting and fledging success of threatened and endangered species like the peregrine falcon. Artificial insemination and special egg incubation programs help to produce young birds which can be released to the wild through a process called hacking - the rearing of young raptors by people without allowing human contact to avoid the possibility of imprinting.


Young raptors may also be placed in wild nests of different bird species. For example, many peregrine falcons have been placed in the nests of prairie falcons and successfully raised by their surrogate parents. This process is called cross fostering.


Additionally, raptor rehabilitation programs are part of an effort throughout the state to help save sick or injured birds. These programs reflect a statewide commitment to restoration and preservation of these species.

Hawks


Accipiters are quick, woodland hunters. Outfitted for speed and agility with short, rounded wings and long tails that help them make sharp turns. Accipiters are primarily hunters of other birds, with some dependence on small rodents. In North America, the three species of Accipiters present are the Sharp-shinned hawk, the Cooper's hawk and the Northern goshawk, all three of which are year-round Oregon residents.

Buteos are hawks belonging to the group of high soaring, open-country hunters that feed mainly on rodents. Buteos are the largest and most easily seen of the hawks. They drift the wind currents high above fields and attack when their keen eyesight reveals a vulnerable target. Surprise is their greatest asset. They descend silently into their prey, striking first with outstretched talons while using wings and tail as brakes. Swainsons, ferruginous and rough-legged hawks are all common Oregon buteos.

Red-tailed hawks are the most common buteos in Oregon. Red-tailed males return from winter ranges in early spring and begin patrolling their territory, establishing dominance and generally laying claim to the area. When the female arrives, the pair will conduct courtship fights. These consist of spiraling climbs almost out of sight from the ground, followed by steep dives and last second pull-ups which hawk watchers refer to as deep-V's.


After courtship, both birds combine forces to build the nest, which is in a new tree each year. The pair may work together, striking a dead tree limb
simultaneously in flight to break it off, then carrying it back to the nest. Redtails feed mostly on rodents but they are also good at catching snakes and
some birds. Should a redtail miss its prey the first time, it can remain on the round and, with wings spread and hooked beak extended, start another attack.  These hawks will sometimes lure a snake into striking repeatedly toward their heavily protected breast, then, when the snake is too tired to defend itself, kill it with tremendously strong talons.


Unlike many other raptors, who will fight to death to protect their young redtails are usually shy around the nest and will abandon their young if real
danger approaches. This action reflects their ability to produce a second clutch of young if the first is lost. It is also an acceptance of the natural truth
that until young animals mature, the adult is more important to survival of the species.

Osprey

Ospreys nest near water. They glide over lakes and streams looking for fish, then come almost to a however, fold their wings and dive, extending
their talons at the last moment to enter the water feet first and grab the fish.

 
Ospreys have a locking feature in their talons which helps keep fish from escaping.It can also get osprey in trouble, if they latch on to a fish
they cannot lift. More than one osprey has been found drowned in a lake, its talons firmly locked to a fish heavy enough to drag the bird below the
surface.
Osprey's eyesight is even more finely developed than that of the other birds of prey, since it must be able to judge the location of their prey
under water. Ospreys must be able to strike the fish where the fish really is, not where the visual shift created by the water makes it seem to be.

Falcon
Falcons are the royalty of meat-eating birds, with blinding speed and a hunter's heart that made them the choice of kings for centuries in the sport of falconry.
Gyrfalcons, prairie falcons, kestrels and peregrines are Oregon visitors and residents.   Peregrines may dive at speeds up to 200 miles per hour and can make complex attacking maneuvers.

In one classic pattern, the falcon dives low under the prey and zooms up to strike it from below, stunning or killing it with the first. The peregrine then
follows the falling prey to the ground, where it recovers and eats it. Even when peregrines are not hungry, they will use their terrifying appearance
to bother flocks of gulls on the beach, chasing them first one way, then the other, then back again. Kingfishers are often victims of the same game--with the peregrine repeatedly chasing the little bird until it dives into the water, squawking with rage. Never let it be said that hawks have no sense of humor.
Peregrines are classified as an endangered species in Oregon. This means that without special protection, they may disappear from the state.

Harriers
Northern harriers, formerly known as marsh hawks, are the only representative of the European harrier family found in North America. Northern harriers are a common sight hunting over fields and marshes with a low-level, organized search. They rarely soar at high altitudes, and are content to hunt near the ground where they can use one of their most-effective weapons, a superb sense of hearing. Harriers often cover more than 100 miles per day in their nearly constant hunt for small mammals.

Eagles
The size and beauty of bald eagles have made them the best known birds of prey. If actions speak louder than appearances, however, the bald eagle is somewhat less than regal. Bald eagles will eat whatever is available. Much of their diet consists of carrion, or dead meat, particularly dead fish, and though they are capable of catching fresh prey, bald eagles are much more likely to steal a fish than to search for one directly. A favorite trick is to wait until an osprey, struggling under the weight of a freshly caught fish, is enroute to its nest, and then attack. The smaller osprey will be forced to release its catch and the eagle will then either catch it in the air or land to enjoy the snack.


Habitat destruction, illegal shooting and use of pesticides drastically reduced the number of bald eagles in the mid-20 century. Since that time they have been making a good comeback, but they are still listed as a threatened species in Oregon. Some bald eagles are year-round residents and nest in Oregon and others that nest further north migrate into the state during the winter months. Oregon's Klamath Basin has a large wintering concentration, making that area a popular eagle watching spot. The largest concentrations of bald eagles are found in Alaska.


Although not decorated with the striking black and white contrasts of bald eagles, golden eagles are perhaps a better symbol of birds of prey. Confident and capable hunters, golden eagles rarely feed on carrion, getting the bulk of their food through attacks on mammals of various sizes, including young livestock and big game species. Golden eagles are year-round state residents and are commonly found in the mountains and high desert country of eastern Oregon.

Owls
Evolution has been kind to owls. Each of the traits that makes them strange and unique also make them more efficient predators. Besides being graced with the superb eyesight common to raptors, the owls' large eyes allow them to see well in the dark. Contrary to popular belief, owls are not blind during the day; they can see in daylight by reducing the size of their pupils just like humans and limiting the amount of light reaching the eye. The third, or nictitating eyelid is also used in some species to reduce admitted light.


Flat-faced owls like the barn owl are most capable of hunting in darkness. Facial feathers are designed to reflect and redirect sounds into the ears.
Such flat-faced owls are able to catch prey in total darkness, using only the sounds made by their victims to direct their attacks.


Owls are equally well equipped to make a minimum of noise, themselves. Feathers on the trailing edges of the owls' wings are soft and flexible; these
features help silence wing noise while the bird is hunting. Most owl victims never have any idea they are in danger until the talons strike.


Not all owls are dedicated night hunters, however. Some, such as the pygmy owls, prefer daylight and have night sight no better than humans. Other
Oregon residents, like the long-eared, spotted and great gray owls are more traditional night feeders.

 
Great-horned owls are the most often seen Oregon owl. Standing nearly two feet in height, and adult great-horned owl is an imposing sight, and even more impressive predator. Although the bulk of their diet is rodents and wild birds, great-horned owls are willing and able to attack small domestic
animals, chickens and ducks. In fact, there are reports of owl attacks on people wearing raccoon or muskrat hats.


Great-horned owls are renowned for their ferocious protection of the nest. No predator, including humans, can approach great-horned owlets without great risk. Ironically, the adult owl's treatment of their own young seems cruel at times, particularly for such devoted parents.


Females lay four to six eggs at the rate of one per day. Incubation begins immediately, ensuring that the first laid will hatch almost a week earlier
than the last. The resulting age differential, small as it seems, leads to the oldest demanding and receiving most of the food. In good years, there may
be enough food to go around, but in lean years, only the oldest one or perhaps two will survive; the rest will starve. Hard as it is to accept in human
philosophy, survival of this species is better served by having one or two strong youngsters leaving the nest rather than six weaklings who shared a
limited food supply.

 
One of the most interesting relationships in nature is that of the owl and the crow. In the spring, when owls need food the most, one of their favorite
meals is crow nestlings, which the owl will steal from the nests at night while the adult crows are helpless. The tables turn during the day, however,
and an owl must take pains to remain hidden after the sun comes up. An owl caught in the open by a flock of crows will be attacked and perhaps killed with much noise and celebration.

Barn Owl, Barred Owl, Screech Owl


Did You Know?
Reflection of sunlight into the eyes can impair eye-sight. Peregrines have evolved a black patch below their eyes which minimizes the problem. A black patch is sometimes painted under the eyes of athletes and combat soldiers for the same reason.


Owls' sense of hearing is heightened by the asymmetrical placement of their ears. This asymmetry (one ear is higher than the other) causes sound to reach their ears at different times. It allows accurate estimates of noise position, even in total darkness.

          Oregon Fish and Wildlife Service.