Raptors or Birds of Prey


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Birds of prey, a special group of birds, are usually referred to as raptors, the Latin word meaning "to seize and carry off." Raptors are very strong birds with hooked beaks and sharp talons for grasping, carrying, and killing prey. Raptors include eagles, hawks, falcons, ospreys, owls, and vultures. Technically, vultures don't have the strong grasping talons of other raptors and they don't, as a rule, kill their prey, but they are considered raptors nonetheless. If you're curious why we call vultures "buzzards" (which are actually European hawks), see the Bulletin Board.

All raptors are protected by state and federal law and some are still on the Threatened and Endangered list (50 CFR 17.11).

We strongly urge any utility with raptors in their service territory to use and bookmark http://www.ris.idbsu.edu. This site has extensive information on the subject of raptors and electrocutions.

Studies and research programs designed to prevent the accidental electrocution of raptors on power lines have been in effect for more than twenty years. The Rural Electrification Administration first issued Bulletin 61-10, "Powerline Contacts by Large Birds", in 1972. Most of the studies have been conducted in the West and most western utilities are familiar with the necessary procedures and design modifications required to reduce raptor contacts. In recent years, however, several types of raptors have begun to re-establish populations in the East and some eastern utilities are now experiencing raptor contacts for the first time. It is important all utilities understand that, because of the raptors' protected status, the burden is placed upon the utility to reduce or prevent raptor electrocutions whether it significantly reduces outages or not. Because of inconsistencies among the various state and federal laws, it is in the best interest of your utility to locate and identify any protected species that may live in your service territory before you have a problem. Stay informed of any raptor re-introduction programs that may affect you.

Eagles. Bald eagles are primarily fish-eaters, either catching their prey near the surface or feeding on dead fish washed ashore. They will eat dead animals and capture water birds when they can. They also have a reputation for stealing fish from smaller birds. Bald eagles apparently mate for life and will use the same nesting site year after year. The nests are great piles of sticks, weeds, and dirt with additions made every year. After twenty years in use, a bald eagle's nest in Ohio measured over 12 feet high.

Like many birds of prey, bald eagles spend much of their time perching motionless, taking in every movement within their wide range of vision. This technique, called still-hunting, is frequently used by bald eagles because it is more "energy efficient" than hunting from the air. Unfortunately, it is also the technique that creates the potential for a fatal electrocution. When still-hunting, bald eagles will usually seek the highest structure for perching and, in some places, the highest structure will be a utility pole.

Golden eagles are big, strong, and aggressive raptors. The females, like most raptors, are larger than the males and may have a wingspan of nearly eight feet. Unlike the bald eagle that usually scavenges for food, the golden eagle is a skillful hunter. Golden eagles are found mainly in the in the West, but there is a small population living in New England. Like the bald eagle, golden eagles apparently mate for life and return to their same nesting site.

Golden eagles use the still-hunting technique from utility poles far more often than bald eagles. The largest population of golden eagles lives in mostly treeless areas where utility poles are the highest points and offer the best view of the surrounding countryside. The large size and abundance of golden eagles make them the most commonly electrocuted raptor. Several studies done in the deserts and flat valleys of the West report approximately 80% of the dead birds in the study sites were golden eagles and most were immature eagles killed during the winter.

Immature eagles are, naturally, less skillful in the techniques of "lift-off" and landings. And, unfortunately, a clumsy or awkward lift-off or landing from or to a utility pole can result in a fatal contact. There is also a logical reason why most of these fatalities occur during the winter. The dry feathers of an eagle are actually good electrical insulators, almost as effective as air. However, wet feathers will cause and sustain arcing at less than 5 kV. Because of their structure, an eagle's feathers will get wetter in snow than rain. The feathers will cause much of the rain to roll off the bird, however, snow remains on the bird and is slowly melted by body heat, soaking into the feathers instead of rolling off. Eagles have a habit of spreading their wings to dry after rain or snow storms. If perched on a utility pole, the eagle's wingspan combined with wet feathers can easily cause a fatal contact.

The power lines most often responsible for raptor contacts are 69 kV and less. Some raptors are large enough for phase to ground contacts on lines of these voltages and eagles are large enough for phase to phase contacts. On transmission lines with voltages higher than 69 kV, the separation of the phase conductors is greater than the wingspan of an eagle so there is no danger of wing tip contacts.

Hawks. Hawks are medium sized raptors, smaller than eagles but large enough to cause outages on power lines. Hawks are found all over the country with the largest types in the western plains. Red-tailed hawks, for example, can adapt to a wide range of territories, but are usually found in open country. Many types of hawks have habits similar to eagles, such as long term mating, returning to the same nesting site, and using utility poles for perching. It is more difficult to establish how frequently hawks and other raptors are electrocuted since other predators often carry the dead birds away. Hawk contacts are probably more frequent than suspected, particularly on transformer poles with bare primary lead wires.

Owls. From the tiny elf owl, less than six inches long, to the massive great gray owl with its five-foot wing span, these night hunters are found throughout the country. The great horned owl is one of the most feared predators in the wild. Many utilities have tried to take advantage of the fear inspired by this bird by mounting fake owls in their substations to keep other birds and squirrels away. Owls are well known for their keen eyesight at night, although they cannot move their eyes. Instead, owls can turn their heads 270 degrees, almost a full circle. Owls also use a kind of sonar to locate their prey. The feathers surrounding their faces "collect" sound waves. An owl's ears are not level, that is, one ear is set higher than the other. This combination allows the owl to determine if the sound is coming from the right or left or up or down. Since most owls catch their prey by surprise, they have special feathers that muffle the sound of flight.

Vultures. With wingspans up to six feet, vultures are the country's cleanup experts. Vultures eat only dead animals and, if necessary, animals that have been dead for some time. In flight, vultures are graceful and impressive, soaring for hours looking for food. As we mentioned before, vultures' beaks are strong and hooked like eagles' although they don't have sharp talons of other raptors. The black vulture is expanding its territory northward from the southern portion of the country and becoming a serious problem for some utilities, causing numerous transmission outages. Like other raptors, vultures will select the highest point in the area for perching. Vultures, however, will perch and roost in large groups, something other raptors don't do. This perching site is often a utility pole, and because of their greater height, usually a transmission tower. Although the energized conductors are far enough apart to prevent wingtip contacts, the perching vultures cause extensive contamination of the insulators with their droppings. Eventually, the contamination will result in tracking and arcing and an outage. To make things more difficult, black vultures, in particular, are easily tamed and appear to have no fear of humans, making it difficult to drive them away.

Ospreys. The osprey has a wingspan of five feet, larger than a hawk but smaller than an eagle. Ospreys hunt like no other raptor. Eating mostly fish, they dive straight down into the water. Since they go completely under the water, their feathers are oily, compact, and somewhat water repellent. Unlike other raptors, the osprey is comfortable living near humans and will frequently build its' nests on utility poles. These very large, bulky nests made from sticks have caused numerous outages. Sticks work their way loose from the nest and fall onto conductors and transformers or are dropped by the osprey. Outages can also be caused by accidental wing tip contacts as the birds fly to and from the nest.

Because of its protected status, osprey nests, no matter how inconveniently or dangerously located, can't be touched without a federal permit. The osprey is one of the birds of prey that is re-establishing a population in the East. There are several research programs that are releasing captive-raised raptors in their original habitats.

RECOMMENDATIONS:
If you would like some help in designing and implementing a comprehensive program for getting your animal-caused outages under control, drop us a line. Don't forget to check the Bulletin Board. If you don't see anything there to help, leave a questionand we'll post it. Be sure to check the Product Catalog to see what commercial products are available.

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