February 2017

Eagles of our time

Marla Mertz, Marion County Conservation, and Linette Bernard, Feathers & Ink

Being children of the 1960s and 70s, there were no sightings or discussions in either of our neck of the woods about the bald eagle. We do recall seeing photos of our national symbol in books. Then, the perspective and importance of predators and large birds of prey were not really understood by most landowners, farmers, and townspeople. Little did any of us know that these awe-inspiring birds would make a comeback in our lifetime!

The bald eagle’s scientific name is Haliaeetus leucocephalus. That is Greek for ‘sea eagle with white head.’ During the colonial times, bald meant white as well as hairless. The bald eagle is only found in North America from Florida through Canada to Alaska. Golden eagles live in North America, but are also found in Europe, Asia, and North Africa. (Golden eagles are occasionally seen in Iowa.)

Congress chose the majestic bald eagle as our national symbol in 1782. At that time, bald eagles were commonly seen in New England along the Atlantic coast. Eagles are ‘opportunistic’ scavengers and will feed on carrion. They are also known to rob or ‘pirate’ another eagles’ catch. Benjamin Franklin was against the bald eagle as our national symbol because of the eagles’ scavenging techniques and wanted the wild turkey instead.

Since the 1800s and until recently, people frequently shot the bald eagle. Many people mistakenly believed eagles could carry away young children. Others hunted eagles for their feathers or killed them because they occasionally preyed or scavenged on livestock. European settlers reduced a great amount of our woodland habitats that drastically altered and reduced the required habitat necessary for the eagles.

After World War II, DDT (an organochlorine pesticide) was used to combat insect-borne human diseases and began negatively impacting the bald eagle (and other top predators). DDT washed into our rivers and streams and accumulated up each level of the food chain... insects to minnows, minnows to larger fish, to waterfowl, to eagles. The natural prey of the eagle was increasingly getting more toxic for them to consume and by the 1960s the toxins interfered with the eagles’ ability to reproduce. The accumulation of DDT causes egg shells to be thin and decreases the viability of that egg. During the 1960s, winter eagle counts documented that there were less than 4,000 eagles in the lower 48 states.

According to an EPA document on the history and status of DDT, “The U.S. Department of Agriculture (USDA), the federal agency with responsibility for regulating pesticides before the formation of the U.S. Environmental Protection Agency (EPA) in 1970, began regulatory actions in the late 1950s and 1960s to prohibit many of DDT's uses because of mounting evidence of the pesticide's declining benefits and environmental and toxicological effects. In 1972, EPA issued a cancellation order for DDT based on its adverse environmental effects, such as those to wildlife, as well as its potential human health risks.”

In 1978 because of the Endangered Species Act, the bald eagle was listed as an endangered species in 43 states and as a threatened species in five others. The Endangered Species Act designations gave the bald eagle increased protections from human impact. With the elimination of DDT in the environment and an increase of successful eagle nestings, the eagle population began rebounding. In 1995, the official status of the bald eagle in the lower 48 states was updated to ‘threatened.’

According to the Iowa Department of Natural Resources’ (DNR) eagle monitoring statistics, Iowa has experienced a dramatic increase in the number of nesting bald eagles over the past 20 years. Nationally, the bald eagle has recovered enough from the dangerously low numbers of the 1960s and 70s that the U.S. Fish and Wildlife Service (USFWS) removed the bald eagle from the Threatened and Endangered Species list in 2007. Iowa followed suit by upgrading the eagle from a status of Threatened to a status of Special Concern on the state Threatened and Endangered list in 2009. Check out this map that shows when an active eagle nest was first documented in each of Iowa’s counties. Click on the map to see it larger and easier to read!

Despite the bald eagle population’s apparent good health, challenges to their conservation still exist. Strategic monitoring of eagle activity in the state, particularly nesting, remains a priority. Learn about how the USFWS is monitoring eagle movements in the Upper Mississippi Valley:

In Marion County, Iowa, from 2015 reports from the Iowa DNR, there are currently 14 territories designated as active out of 20 total territories recorded in the county. The defined terminology of “active territory” used by the Iowa DNR is “A habitat area up to one (1) mile in radius (though sometimes smaller in good habitat) that is defended by a pair of eagles and used for breeding. Meets all breeding habitat needs including appropriate trees (or, on rare occasion, other structures) to build nests and a nearby food source. A territory may hold more than one (1) nest but may not house more that one (1) pair of eagles within the same breeding season. The pair of eagles need not be the same pair across years.”

When a new nest is reported, every effort is made to determine whether it belongs to an existing pair or represents a new territory. Currently, Iowa holds approximately 256 active eagle nests and there are 14 active nests in Marion County. The Iowa DNR definition of “active nest” is “… any bald eagle territory that has had some eagle activity within the previous two years of the current nesting season; activity does not imply breeding success.”

Marion County has been well known throughout the state for the concentrations of wintering eagles. Lake Red Rock, the largest lake in Iowa, doesn’t ordinarily freeze until mid-December, so viewing is random. Once the lake freezes, our year-round resident eagles and migratory birds find shelter and open water below the dam and throughout the area down river. People come from all over to view the eagles around the Lake Red Rock area.

“To some of us, the monitoring and research is just one important aspect of continuing our learning about the bald eagle. Observations, awareness of our environment, the importance of our rivers and the river communities, and the basic understanding and comprehension of predator and prey relationships are also an integral part of eagle stewardship. When a connection is made to these majestic symbols, a ‘sense of place’ within our environment seems to emerge. I am asked on many occasion if ‘eagle work’ is done. My answer is... not by a long shot! There is much more to do. ‘Eagle work’ isn’t just about the bird, it’s the rivers, the corridors, and the health and diversity of it all.” ~ Marla Mertz

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