Story and photos by Tom Hodgson
In 2009, there was a great deal of excitement among area birders when a pair of bald eagles began building a nest in a large cottonwood in a remote area in Northeastern Jackson County.
As is often the case with first time nesters, no eggs were ever laid. The following March, hopes were raised again as the pair added more material to the nest. However, early in this nesting cycle one of the pair mysteriously disappeared and nesting ceased once again.
In 2011, two adult eagles returned to the nest and once again began adding material in preparation for nesting. They laid two eggs, and after 35 days of incubation, hatched two young eaglets. Biologists from the DNR non-game wildlife program examined and banded the young while still in the nest and found them in good health.
Once the young leave, they may not return to the nest again, but remain in the territory for the rest of the summer. They spend most of their time perched in nearby trees waiting for their parents to feed them. The parents are very obliging, keeping them well supplied throughout the summer months.
When the young birds are four or five months old, this gravy train ends and they are left to fend for themselves.
Eagles may use the same nest for many consecutive years, adding new material each season. As a result, some nests may weigh as much as two tons. Eventually the trees they are in can no longer support them and they come crashing down.
Life is hazardous for young eagles. Fifty percent die during their first year of life. Some are victims of accidents while learning to fly, while others die of starvation before they fully acquire their hunting skills. Those that survive will not gain their adult plumage (white head and tail feathers) until they are four or five years old. If they survive their first year, they may live another 15 to 20 years in the wild.
Until they reach maturity, these young birds will lead nomadic lives, often in association with other immature eagles. When they reach breeding age, they may return to the general area from which they were fledged to establish territories of their own. Not too close, however, as their parent’s territory (if still occupied) may extend up to two square miles. More likely, the nest site they choose will be five to ten miles from their birth nest.
The bald eagle has made a remarkable come-back. In the 1960’s wide-spread use of the pesticide DDT reduced their population to just 400 nesting pairs in the lower 48 states. At that time, there were fewer than 30 nesting pairs in Michigan. The pesticide caused a thinning of the eagle’s egg shells, making them unable to withstand the weight of the adult birds during incubation.
The banning of DDT in 1972 and the passing of the Endangered Species Act in 1973 are largely credited for the bald eagle’s recovery.
Michigan now has more than 800 nesting pairs including two in Jackson County and three in Washtenaw County.
Both adult and immature bald eagles are seen with increasing frequency in our area. I have personally observed eagles fishing in Cavanaugh Lake, and even spotted an adult perched in a tree at the east end of my property.
The sexes are colored alike, with brown bodies and white heads and tails. The females are usually larger. A male may weigh up to 10 pounds and have a six-and-one half to seven-foot wingspan. A female may reach 14 pounds and have an 8-foot wingspan. The immature birds are a mottled brown with a brown beak. Their wings are also shorter and broader than the adults.
Although bald eagles prefer fish, they will also prey on waterfowl and small mammals. Their eyesight is five to eight times more powerful than our own. While soaring high above the earth they are able to spot the movement of a rabbit over a mile away.
Eagles are truly fierce and handsome birds, except for their voice, which is kind of wimpy. As a result, when filming eagles, cinematographers would often substitute the screaming call of a red-tail hawk. To hear how eagles really sound, click here.
Soaring turkey vultures are sometimes mistaken for immature eagles. Turkey vultures have no feathers on their heads and soar with their wings in a shallow V. Eagles soar with their wings flat.