An Eagle Eye

June 17, 2008
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Surveyors not only protect the public, they protect our country's symbol, the bald eagle, as well.


In 2005, I performed an ALTA/ACSM Land Title Survey of a very large tract of property along Lake Erie in southeast Michigan. Sounds straightforward, but there was a challenge that lay before me: The lakefront property contained an active bald eagle nest.

From the start, I knew the survey would be both historic and challenging. But the bald eagle nest full of fledglings added a whole new dimension. For one thing, I wasn’t sure if I had to show the nest on my survey. But after hours of research, I realized not only the importance of this inclusion but the number of limitations I needed to record around the nest. These lessons were coupled with the correct way to accurately identify the bird and field-locate its nest. Since the completion of my survey, the bald eagle has been taken off the federal list of endangered species. But what does this mean to the surveyor, engineer and developer? Does it matter if the bald eagle nest you encounter while surveying is active or inactive? How do you positively identify bald eagles and their nests? What penalties are associated with laws that protect the bald eagle? As surveyors, we should be able to answer these and many other questions.

It is important for surveyors to know when the bald eagles in their state are building nests, laying or incubating eggs, hatching or rearing young, and when the young are fledging (growing feathers for flying).

Identifying the Bald Eagle and its Nest

To a birdwatcher, the bald eagle is simple to spot, even from a half-mile away. The key to proper identification is not simply knowing what a bald eagle looks like but knowing what similar species look like and how to tell them apart.

An adult bald eagle--one five years and older--is fairly easy to identify with its distinctive bright white head and tail, dark brown body and yellow beak. But the younger bald eagle looks very similar to a juvenile golden eagle. The key difference is that the juvenile bald eagle has a much larger head and smaller, blotchier tail. By contrast, the juvenile golden eagle has a distinctive pattern on the underside of its body.

Also misidentified as a bald eagle is the turkey vulture. From a distance, the turkey vulture may look similar, but in reality, it has no head feathers. Additionally, the turkey vulture holds its wings in a “V” shape when soaring, known as a dihedral angle, while the bald eagle’s wings are held almost perfectly flat with no dihedral angle.

The black vulture and the California condor can also be mistaken for the bald eagle. The black vulture, however, is much smaller, lacks feathers on its head and only has whitish feathers on the tips of its wings. The very rare condor, found only in Southern California and northern Arizona, is much larger.

For the land surveyor, identifying a bald eagle nest, or aerie, is crucial to the successful completion of a survey. Most bald eagle nests are located along a seacoast, marsh, lake or river. Bald eagles like a clear view of the water and prefer to nest in the tops of high trees, around 75 feet high. Most bald eagles use the same nest year after year, simply enlarging it each new year. Some nests and their territories have been used and maintained for more than half a century.

It is hard to mistake a bald eagle nest, mostly because of its gigantic size. Most nests are around 5 to 9 feet in diameter and grow larger every year, sometimes breaking the limbs of the trees they are in. Eric Stiles of the New Jersey Audubon Society was quoted in an article in The Press of Atlantic City saying, “A bald eagle nest in a tree is like a VW parked in the top of that tree.”

Nests can take three different shapes. If the nest rests in the fork of a tree, it takes more of a conical shape. Ground nests and those on flat branches take on a disk shape. The most common nest, the bowl-shaped nest, is found where branches fork out to form smaller branches. Nests in question should be directed to the surveyor’s local Department of Natural Resources or U.S. Fish and Wildlife Service (FWS).

Surveying Around a Bald Eagle Nest

Every state has different date ranges pertaining to the bald eagle’s reproductive activities, so it is important for surveyors to know when the bald eagles in their state are building nests, laying or incubating eggs, hatching or rearing young, and when the young are fledging (growing feathers for flying). The chart on page 22 will help to determine the best time to survey around a bald eagle nest without disturbing it. Surveying activities near an active bald eagle nest are best performed when they are not in the reproductive stage or when they are migrating. But great care and respect should be taken at all times of the year. Fortunately, technological advancements like reflectorless total stations and aerial photogrammetry allow most field work to be performed without disturbing a nest.

One of the most important parts of a land survey involving a bald eagle nest is locating the nest with precision and accuracy. When I was first challenged with locating and working around an active nest in the spring of 2005, I used aerial photogrammetry to locate features around the nest and set control far from the nest with appropriate geometry to triangulate its position without actually getting near the nest. Today, I would still use triangulation with good geometry, but I would check myself with a reflectorless total station. Surveyors must understand that the horizontal location of the bald eagle nest is critical to setting up the distance buffers necessary to protect the bird’s habitat.

The author is introduced to a healthy bald eagle by Mona Rutger, a licensed rehabilitator at Back to the Wild Wildlife Rehabilitation and Nature Education Center in Castalia, Ohio.

Acts of Protection

The Bald and Golden Eagle Protection Act

Commonly called the Eagle Act, the Bald and Golden Eagle Protection Act, which was enacted in 1940 and has since undergone several amendments, protects our country’s bald eagles from being taken, possessed, sold, purchased, bartered, transported, exported or imported. The definitions within the act are controversial and most often interpreted to be in regard to the eagle itself, not its habitat.

Harsh penalties are outlined in the Eagle Act. According to Nicholas Throckmorton, a public affairs specialist for the FWS, the first criminal offense is a misdemeanor with a maximum penalty of one year in prison and $100,000 fine for an individual ($200,000 for an organization); the second offense becomes a felony with a maximum penalty of two years in prison and a $250,000 fine for an individual ($500,000 for an organization). The act also provides for maximum civil penalties of $5,000 for each violation.

In September 2005, a development company in Florida was fined $356,125 and an individual from the company was fined $5,000 and three years’ probation for destroying a bald eagle nest on the property of a proposed development. Earlier that year in Florida, two individuals cut down a tree that held a bald eagle nest. One of them was fined $10,000 and was ordered to pay $80,000 in restitution to the Audubon Center for Birds of Prey and the National Fish and Wildlife Foundation’s Florida Bald Eagle Conservation Fund. The other party was also fined $10,000 and had to forfeit his chainsaw. Recently, a 70-foot pine tree was cut down in Millville, N.J., and the local Audubon Society and the FWS have teamed up to offer a $3,500 reward for information on who cut it down. Prosecution will fall under the Eagle Act.


The Migratory Bird Treaty Act

Originally created by the federal government in 1918, the Migratory Bird Treaty Act (MBTA) did not include the bald eagle until 1972. This act was made to implement the United States’ treaties (conventions) with Canada, Mexico, Japan and Russia. According to the FWS, “The conventions protect migratory birds as an international resource.” Much like the Eagle Act, the MBTA includes language to protect any part, nest or egg of any bald eagle or other migratory bird unless a permit is applied for and granted.

The penalties are equally harsh for the MBTA as they are for the Eagle Act. “‘Take’ alone is a misdemeanor violation with a maximum penalty of six months in prison and a $15,000 fine. And commercialization is a felony violation with a maximum penalty of two years’ imprisonment and a $250,000 fine--$500,000 for an organization,” says FWS’ Throckmorton. Take, according to the FWS, is defined in the MBTA to include by any means or in any manner, any attempt at hunting, pursuing, wounding, killing, possessing or transporting any migratory bird, nest, egg, or part thereof.


The Lacey Act

Created in 1900, the Lacey Act is the least commonly used of the federal laws protecting the bald eagle. This act prohibits the transport of an illegally taken bald eagle and other wildlife across state lines. Similar to the Eagle Act and the MBTA, this includes the importing, exporting, selling, acquiring, possessing, transporting, etc. of the bald eagle as well as its feather, parts, nest and eggs.

According to FWS guidelines, penalties include a maximum of five years in prison and a $250,000 fine for felony convictions, a maximum $10,000 fine for civil violations and a $250 fine for marketing violations. The maximum criminal fine for an organization is $500,000.


Individual State Laws

While most states fall back on federal regulations for protecting bald eagles, some states have laws that protect eagles beyond federal law. Many states, in fact, have reclassified the bald eagle from endangered to threatened. According to the FWS and the Florida Fish and Wildlife Conservation Commission (FWC), Florida had 1,133 breeding pairs of bald eagles in 2006. The Center of Biological Diversity (CBD) records Florida as having 1,166 breeding pairs and notes that it “supports the highest number of breeding bald eagles in the lower 48 states and represents roughly 10 percent of the breeding population in the lower 48 states.” The center further states that bald eagles “currently nest in 59 of 67 counties in Florida.” To protect these numbers, Florida has multiple laws and is currently working on a bald eagle management plan.

National Guidelines

In May 2007, the FWS published the National Bald Eagle Management Guidelines in response to the bald eagle’s delisting from the federal endangered species list. The guidelines do not cover state or local municipality laws, which may still list and protect the bald eagle as endangered or threatened. Therefore, it is every surveyor’s responsibility to know which laws pertain to his or her working environment.

The national guidelines have three fundamental intentions:

• to publicize the provisions of the Eagle Act that continue to protect bald eagles in order to reduce the possibility that people will violate the law;

• to advise landowners, land managers and the general public of the potential for various human activities that disturb eagles; and

• to encourage additional nonbinding land management practices that benefit bald eagles.


The guidelines provide details pertaining to the natural history of the bald eagle, where bald eagles nest, when bald eagles nest, how many chicks bald eagles raise and what bald eagles eat. They also discuss the impact of human activity on nesting bald eagles and foraging and roosting bald eagles, particularly at communal roost sites, as well as the accompanying recommendations for avoiding site disturbance. According to the guidelines, a foraging area is “an area where eagles feed, typically near open water such as rivers, lakes, reservoirs and bays where fish and waterfowl are abundant, or in areas with little or no water (i.e., rangelands, barren land, tundra, suburban areas, etc.) where other prey species (e.g., rabbits, rodents) or carrion (such as landfills) are abundant.” A communal roost site is an “area where bald eagles gather and perch overnight and sometimes during the day in the event of inclement weather. Communal roost sites are usually in large trees (live or dead) that are relatively sheltered from wind and are generally in close proximity to foraging areas. These roosts may also serve a social purpose for pair bond formation and communication among eagles. Many roost sites are used year after year.”

The guidelines also provide activity-specific guidelines in different categories, including building construction, timber operations, human entry and many others. They recommend specific buffers around the activities like 330 feet, 600 feet or even a half-mile in some cases. Finally, the guidelines provide a full list of pertinent definitions, recommend ways to benefit bald eagles and include contact information for every state.

Surveying activities near an active bald eagle nest are best performed when they are not in the reproductive stage or when they are migrating.

Protecting Our Nation's Symbol

The battle for valuable waterfront property will continue between the bald eagle and the land developer. To protect our nation’s symbol, it is our obligation as professional land surveyors to adhere to the guidelines that the FWS has established and educate others on the federal regulations protecting bald eagle habitat. In our profession, we protect not only the public but this distinctive bird of prey, as well.

The FWS National Bald Eagle Management Guidelines include this chronology table of typical reproductive activities of U.S. bald eagles.

For the federal laws protecting the bald eagle and to view the National Bald Eagle Management Guidelines, go to the U.S. Fish and Wildlife Service’s Web site at www.fws.gov.

Sidebar: Bald Eagle History

It is estimated that there were more than half a million bald eagles in the United States before European settlement. The biggest threat to the bald eagle has always been humankind. In fact, in Alaska between 1917 and 1952, a bounty was placed on the bald eagle, and according to the Bureau of Land Management, more than 100,000 bald eagles were killed as a result. At the same time, concern was growing about diminishing populations in the lower 48 states, and in 1940, Congress enacted the Bald Eagle Protection Act.

During the 1940s to 1960s, according to the U.S. Fish and Wildlife Service (FWS), our nation’s water became polluted with the dumping of 675,000 tons of the pesticide DDT. The bald eagle’s main food supply--fish--became contaminated. This disrupted the bald eagle’s reproductive cycle, and in 1963, there were only about 400 breeding pairs in the contiguous United States. From the efforts of Rachel Carson in 1972 and her book “Silent Spring,” the Environmental Protection Agency was formed and DDT was banned. Soon after, in 1973, the Endangered Species Act (ESA) was established, and the bald eagle was placed at the top of the list.

Even with the odds against them, the bald eagle has come back. Now, there are more than 10,000 breeding pairs in the contiguous United States with at least one pair in every state. Therefore, in 1995, the bald eagle was moved from endangered to threatened. In 2007, the bald eagle was taken off the ESA list and the species is now protected under three separate federal laws enforced by the FWS.

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