In Flight: Bald Eagle De-listed in Michigan
May 5, 2009
As yesterday’s Traverse City Record-Eagle reported:
The bald eagle is now off both state and federal endangered species lists for Michigan. But the federal Bald Eagle Protection Act of 1940 makes it a crime to hunt, kill or otherwise harm them.
Fewer than 100 nests existed in the state in 1969, DNR officials said. In 2006, there were nearly 500 occupied nests, and the number is growing.
The Michigan DNR page on the Bald Eagle in Michigan has lots of information about their seasonal behavior (they are beginning to hatch their eggs right now) and documents the history of the bald eagle in Michigan:
Before European settlement, bald eagles probably nested in all regions of Michigan where food was available. In the early 1900s they were described as being “generally distributed,” but “nowhere abundant.” A decline through the early and mid-1900s was probably related to slow but consistent loss of suitable habitat and available food, and predator control by humans. These eagles are so disturbed by the presence of humans near their nest that they may be induced to abandon the nest, or even chicks that have already hatched. By 1959, the species was considered, “largely restricted to the northern half of the state.”
Through the 1950s, the slow decline accelerated dramatically, until suddenly, bald eagles were on the brink of extinction in the lower 48 states. The population crash was due to several factors that had reduced reproductive success of nesting pairs, but was mostly the result of increased use of pesticides with chemicals such as PCB and DDT. These chemicals affected the eagles in many ways, including causing them to delay their breeding until it was too late in the season, or even to not breed at all. Eggs that were laid often had thin shells, causing them to break in the nest. At its worst in 1967, only 38 percent of the Michigan population of bald eagles were able to raise at least a single chick. Productivity must be at least 70 percent for a bald eagle population to remain stable.
Recognition of the plight of bald eagles in the US and its cause finally occurred in the 1960s. By the 1970s DDT had been banned in the US. Intensive monitoring of eagles in Michigan began in 1961. Although bald eagles had been protected at federal and state levels since 1940 and 1954, respectively, they received much greater protection after the ratification of the Endangered Species Act in 1973, and the Michigan endangered species act in 1974.
Reproductive success began to improve and in 1975, the 70 percent productivity mark was reached, although it dropped off again soon after. The population remained at around 86 nesting pairs through the 1970s. In 1981, the population at last began to increase. The 1999 survey found 343 nests that produced 321 young. The productivity was calculated as 96% (young per nests with known outcomes). But some problems still exist. Eagles nesting along the Great Lakes coasts have higher contaminant levels in their blood than inland nesting pairs.
The American Bald Eagle information site has all kinds of sighting information from Michigan and will help you find places to see bald eagles.
If you’d like to check them out from your computer, you can see the above photo background big or in Bob’s Eagles set (slideshow, check out the Bald Eagle slideshow in the Absolute Michigan pool and/or Michigan Bald Eagles on Flickr.