Poking Around in Maine
The Eagles of Kenduskeag Avenue
Bangor
by Craig Mains
The Eagles of Kenduskeag Avenue
by Craig Mains
One of the pleasant surprises of visiting Chain-Wen in Bangor was finding out there was a bald eagle nest with two eaglets just a few houses down Kenduskeag Avenue. We could see the nest from the front of Chain's house, although because the nest was up pretty high we couldn't see them all that clearly. Fortunately, my vest-pocket camera has decent zoom-ability.
We knew the eaglets were always in the nest but they weren't always visible. The adults seemed to be gone most of the time. In the photo above, one of the adults and both of the juveniles are visible, although only one of them has its head up. It appears to be mealtime.
photo taken 6-17-2022
This photo shows that there were two eagle nests in the tree. We only ever saw any activity in the upper nest. It was hard to estimate the size of the nests because they were so high. The average width of a bald eagle nest is four to five feet with a depth of two to four feet. The average weight is about one ton. Because the eagles reuse the nest from year to year and add new material each year they can become huge. One nest was estimated to weigh three tons. They have been known to pull down the tree in which they are built.
From the outside the nests don't look all that comfortable but the inside of the nest is lined with softer materials such as mosses, grass, lichens, down, or whatever material is locally available.
I was surprised to see eagles nesting in the middle of an urban area. I had assumed that they would be adverse to nesting in areas with a high level of human activity. Apparently, it is no longer that unusual
American bald eagles are considered a conservation success story. In 1963 there were only 417 nests counted in the lower 48 states and there was some concern that they would become extinct in the US outside of Alaska. Since then, they have made a remarkable recovery with the number of bald eagles in the lower 48 states growing exponentially. The timeline above shows the recovery. The number of breeding pairs of eagles has more than doubled just within the past 10 to 15 years. The total population of bald eagles in the lower 48 states more than quadrupled in just 10 years, increasing from 72,434 in 2009 to 316,700 in 2019. What makes this more remarkable is that in general the overall number of birds of other species in the US has generally declined.
Besides being declared an endangered species, the recovery has been attributed, in part, to the banning of DDT in 1972. DDT was found to cause thinning of bird shells resulting in pre-hatch mortality. The Bald and Golden Eagle Protection Act was amended, also in 1972, greatly increasing the penalties for killing, owning, buying, or selling eagles, alive or dead, including nests and eggs.
The rebound in the number of eagles raises the question of whether eagles have moved into urban areas because they have become more comfortable around humans now that they are less persecuted, or if they have been forced to live near humans because the increased number of eagles has caused some pairs to accept less desirable nesting locations. It is possible that both are true. Regardless, the presence of bald eagles in urban and suburban areas has become more common. [1]
Both of the juveniles in the nest. It was hard to get a decent picture of the eaglets in the nest because there was only one angle from which a good photo was possible and because for most of the day the birds were backlit so that they often just showed up as a silhouette. It was only in the late afternoon and early evening that they were front-lit and they weren't always active then.
Bald eagles usually lay one to three eggs. Where food is scarce the parents may preferentially feed only one of the juveniles, usually the first hatched. The other juvenile(s) may sometimes starve to death. Both of the Kenduskeag juveniles seemed about the same size so there must have been adequate food available.
photo taken morning 6-20-2022
While I was in Bangor in June it appeared the birds were getting ready to fledge and we would sometimes see one or the other of the eaglets stretching their wings.
photo taken morning 6-20-2022
I was finally able to get a photo when the subject wasn't backlit.
photo taken early evening 6-20-2022
It was unusual that both juveniles were visible at the same time. Sibling rivalry, it seems, is not uncommon with bald eagles. Bald eagle juveniles have been known to kill their siblings.
The first year of life for bald eagles is the most perilous. It is estimated that 30 to 50 percent of bald eagles don't survive through the first year. If they survive the first year, their odds of surviving the next year increase to 90 percent. Bald eagles can live 20 to 30 years in the wild, longer in captivity.
photo taken 6-24-2022
The adults seemed to be away a lot, probably hunting for food. Occasionally we would see one or the other of them perched in an oak tree that was almost directly across the street from Chain's apartment, which was probably 100 yards from the nest tree. I imagined that they were staying close enough to keep an eye on the nest but far away enough to get a break from the incessant demands of the eaglets for something to eat.
photo taken 6-30-2022
I was back in West Virginia in July and August, during which time the eaglets fledged. For a while, when I came back to Bangor in September I didn't see either the adults or the eaglets. Then we started to intermittently see both the adults and the juveniles alone or in combination.
Above is a photo of one of the juveniles in the oak tree across the street from Chain's apartment. It takes a young bald eagle about five to five-and-a-half years to fully achieve adult plumage. A first-year juvenile is mostly all brown with white flecks on its wings and belly. Its head and upper breast are a darker brown than the rest of its body. Besides the changes in the plumage, over the roughly five years it takes the bird to reach maturity, its beak will change from a slate gray color to yellow and its irises will change from dark brown to a pale yellow color. Its legs and talons will become a darker yellow color.
photo taken 9-16-2022
Shown above is a photo of one of the sporadic visits of one of the adults and one of the juveniles to the nest tree. In the fall we heard the eagles more than we saw them. They would occasionally perch in the tree across the street around 4:30 am squawking and chirping. By the time it was light they were gone.
photo taken 9-27-2022
This photo was taken from Chain's third-floor attic bedroom. Although they frequently perched in the tree across the street, they were rarely visible from inside the house. They seemed to have a favorite branch, which wasn't visible from inside. This was the only time I was able to take a photo at roughly the same level as the eagle. All the other times I was taking photos looking up at them.
I like how the dark feathers are all edged with a lighter color.
photo taken 10-11-2022
This was the only photo I was able to get that showed the adults together. Bald eagles display reverse sexual dimorphism. Sexual dismorphism is when one sex is noticeably larger or different in form than the other. With many animals, the male is larger but in the case of bald eagles, the female is larger. Females generally weigh about 14 pounds with a wingspan of seven to eight feet. Males weigh about 10 pounds with a wingspan of about six feet. In the photo above, the eagle on the right appears to be larger and is most likely the female.
Ornithologists aren't sure why females are larger but theorize that a larger body mass may be an advantage for incubating eggs since they generate more body heat. It is also thought that the smaller size of the male makes him more maneuverable and a better hunter, which is important since early on the female doesn't leave the nest and the male does all the hunting. Although the maximum size of prey the male is able to carry is smaller, some researchers think the smaller male is able to bring back more total mass of prey.
photo taken 10-12-2022
Bangor seemed to have a lot of crows and we would sometimes see them harassing the eagles, both the adults and the juveniles. In this photo one of the juveniles is in the center of the photo surrounded by crows. The photo shows only about a quarter of the actual number of crows that were perched in something of an orb around the lone juvenile. Usually we saw them actively harassing the eagles but in this case they were just silently perched around the eaglet. I'm sure they were still getting their point across.
the last Kenduskeagle photo, taken 10-12-2022
I have to wonder, if the population of bald eagles in the lower 48 states quadrupled in the last 10 years, what will the population be in another 10 years? Is it possible that they will be so common that we will get used to seeing them? That's hard for me to imagine. I never saw a bald eagle until I was an adult and rarely ever saw a hawk as a child. I think it will always give me a thrill no matter how common they become.
Footnotes
[1] Not all the news about bald eagles is positive. Researchers recently evaluated lead exposure in 1210 golden and bald eagles from 38 US states, including both living and dead eagles. The found that almost half of the eagles showed evidence of chronic lead poisoning (as measured by lead in the bones) and 27 to 30 percent of bald eagles had acute lead poisoning (as measured by lead in the liver, blood, and feathers). It is believed that most of the lead is taken in when eagles scavenge entrails contaminated with fragments of lead ammo that are left behind by hunters who field dress animals they kill. The lead poisoning isn't limited to eagles but also affects any animals that scavenge, including vultures, owls, crows, coyotes, foxes, bears, etc.
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