The Return of the Bald Eagle

My initiation to wildlife in Door County, including both plants and animals, began in the summer of 1964. My friend and outstanding mentor, Miss Emma Toft, sadly informed me that the Bald Eagles no longer nested after the late 1950s at Toft Point near Baileys Harbor as they had for many years. Similar to what had happened in many areas of North America, the eagles had been killed by DDT. Its use as an agricultural chemical had skyrocketed after World War II.

Birds high on the food chain, including large birds such as Bald Eagles, slowly built up dangerous levels of the deadly chemical in their bodies. Gradually, their calcium metabolism was upset to the extent that their egg shells were about 25 percent thinner than normal and no longer strong enough to support the weight of an incubating female eagle. The parenting behavior of the adults also changed to the detriment of the surviving young. The number of nesting Bald Eagle pairs in Wisconsin had plummeted to a low of 25 in 1962.

Elsewhere on the North American continent, Bald Eagles were decreasing in population due to other forces. For example, a bounty on Bald Eagles was begun in Alaska in 1917. A total of 41,812 were shot within the first 10 years of the bounty; 128,000 were killed in Alaska from 1917 to 1952. It was because the eagles competed with the Alaskan fisheries that these large birds were considered vermin. Today, protected by federal law, as many as 3,000 to 4,000 Bald Eagles may gather in mid-November just along a 10-mile stretch of the famous Chilkat River in Alaska to feed on dead or spent salmon.

Rachel Carson’s excellent hard-hitting book, Silent Spring, was published in 1962 marking the start of a strong campaign to outlaw DDT in the U.S. and the world. The fight was initiated by the Wisconsin CNRA (Citizen’s Natural Resources Association – still active and operating), spearheaded by Professor Joseph Hickey of University of Wisconsin-Madison. It was he who traced and proved that both the Bald Eagles’ and Ospreys’ plummeting populations were caused by DDT. By 1972 most uses of DDT in the U.S. were banned. Along with the passage of the Endangered Species Act, the ban on DDT is cited as a major factor in the excellent comeback of Bald Eagles and Ospreys. There were 1,142 documented Bald Eagle nests in Wisconsin in 2008, up from 25 in 1962!

The northern tier of counties in Wisconsin has the majority of nesting eagles. Vilas topped the state in 2008 with 149 occupied Bald Eagle territories. Others were Oneida County (121), Iron County (32), Ashland County (22), Bayfield County (22), and Douglas County (39). In northwestern Wisconsin, Burnett County had 73 occupied eagle territories, while Washburn County had 52, and Sawyer County had 67. Door County last year had seven occupied territories, and Oconto County across the bay to the west had 12 while Marinette County had 25. Occupied eagle territories are those territories where the observer records at least one of the following:  a repaired nest, an incubating adult, eggs, or young in the nest. The annual aerial survey done by the Wisconsin Department of Natural Resources (WDNR) doesn’t imply that every active nest in the state has been accounted for. Some new nests, especially those away from a shoreline, can “hide” and don’t show up well from the air.

Emma Toft once related to me how her sister Lucy’s daughter, Virginia, and Lucy’s younger sister, Elsie, used to spear carp during the 1940s in the shallows of Mud Bay (now referred to as Moonlight Bay) at Toft Point. They then pulled the stringer of large carp down to the rocks where they were left for the Bald Eagles to feast on. It didn’t take many days for those “rough fish” to be completely consumed. A picture of Virginia and Elsie pulling the big stringer of dead carp appears on page 84 of my book, Toft Point, A Legacy of People and Pines.

The Bald Eagle is one of the so-called “sea eagles” and is very well suited to nesting in Door County with its many miles of lakeshore. Their food consists largely of fish; injured, shot or crippled waterfowl, muskrats, squirrels, rabbits, etc.; and also traffic-killed animals or other carrion.

All of the nests we’ve observed in Door County have been built in tall White Pines. The top of one of the nests we have measured in winter is about 90 feet above the ground. It is common for a pair of eagles, who mate for life, to build two or three nests. Whether this is for security or sanitation purposes is not known. Sometimes a tall nest becomes too heavy, moves in high winds or simply caves in due to the extreme weight. The majority of the nests are built quite close to water. However, one active and successful nest we know about, high in a White Pine along the edge of a farmer’s field, is at least two miles from the shore of Green Bay.

This past spring, friends of ours, Arvid and Lola Munson, who live high on the wooded escarpment south of Ephraim overlooking the valley connecting Eagle Harbor and Baileys Harbor, watched an adult pair of Bald Eagles carry away beaks full of straw from a couple of bales in their yard, presumably with which to line their nest. The nest’s foundation of heavy sticks is often padded with moss, pine needles, grass, straw, feathers or other soft materials.

A strong pair bond will have been re-established early in the year and by February their nesting site has been reclaimed. The female usually lays two white, three-inch long eggs in late March or early April. Both adults incubate the eggs starting when the first one is laid. The extremely critical period, when these nesting eagles need solitude and lack of human disturbance, begins just before egg laying and ends three weeks after the young have hatched. With incubation being approximately 35 days, this extremely sensitive period runs for around 90 days, through the end of June. Actually it’s best to keep your distance from the nests until early August. In the case that you do know of the location of a nest, please remain completely away from the nest. Be satisfied to see the birds by chance in the air. Remember that juvenile Bald Eagle mortality amounts to over 50 percent every year.

What provided members of the Toft family, and others, with great pride and satisfaction is knowing that the Toft Point White Pine forest was the last known successful nesting site for the Bald Eagles in Door County in the late 1950s and also the very first known successful site to be re-established in the early 1990s in Door County.

Please know that we can help the WDNR Bureau of Endangered Resources (BER) in its efforts to increase the population of Bald Eagles in our county and state. Become more informed about these great birds and help others to understand and respect them better, too. Report active nest locations to the BER, avoid eagle nests during the breeding season (February 15th through August 1st), and volunteer to participate in the winter Bald Eagle survey. Also of great importance is to work diligently to keep Door County wild!

How wonderful it is knowing that our great county has plenty of wildness remaining suitable for our national bird, the awesome Bald Eagle, to nest in and raise their young.