March 31, 2025 - The Mighty Bald Eagle

The Bald Eagle (Haliaeetus leucocephalus) has become a widely known species in the US since becoming the country's symbol in 1782. However, this bird has been recognized and revered by many across North America for long before that, especially native tribes like the Ojibway, Cree, Haudenosaunee, and Lumbee. Adult bald eagles can be identified by their large yellow bills, white head and tail feathers, brown body and wing feathers, and large body size. 

If you live in or have explored Maine in recent years you have likely spotted these gorgeous birds before -  soaring high above, perched in large white pines, or waiting impatiently by your ice fishing tent for a free snack. But how well do you really know them? 

Winter Gathering 

Bald eagles are generally solitary for most of the year -  coming together for nesting, mating, and rearing young in monogamous couples from late winter to late spring.  However, if you visited Hirundo this winter you may have spotted a handful of bald eagles hanging out just off of our Wabanaki trail. Some visitors let us know they even spotted up to 12 at once along Pushaw stream! To some this may seem like a bizarre occurrence but it is actually quite typical of this species in the winter season. 

In winter, year round wildlife species must cope with a massive change in resource availability. Drops in temperature and the presence of ice and snow creates a challenge for insectivores, herbivores, hunters, scavengers and everything in between. Bald eagles are opportunistic carnivores. They consume a variety of prey and spend time hunting and scavenging. However, fish are a large part of the bald eagles diet throughout their range. Due to their strong preference for fish and the fact that most rivers and streams are frozen over in winter, the section of Pushaw Stream at Hirundo provides an ideal wintering spot for bald eagles. Since it remains ice-free all season, it offers a reliable place for them to hunt and rest! 

Conservation Success 

Though it is not uncommon to see large groups of bald eagles gathered now, that was not always the case. Bald eagle populations nearly collapsed in the mid - 20th century and the birds even made the endangered species list for a while. The use of DDT, a previously popular pesticide, resulted in detrimental impacts on bald eagles and other birds of prey. Since DDT bioaccumulates these birds were particularly vulnerable to this issue as they exist at a much higher point in the food chain. The outcome was severe thinning of eggshells. These thin shelled eggs were often broken during the incubation period. Luckily, this issue was brought to light and DDT was banned in 1972. Bald eagle populations rose from just 417 known nesting pairs to about 316,000 individuals today! 

Spring Dispersal & Territoriality 

If you visit Hirundo now, in March, you may spot one or two individual bald eagles but are unlikely to run into large groupings. Why is that? There are a few reasons for this. For one, temperatures are rising and streams, rivers, and even some lakes are already icing out and more resource opportunities in different areas are becoming available. Another reason is that it is their breeding season! During winter, eagles and many other birds become less territorial and are more willing to exist surrounded by others. As breeding season begins late winter, bald eagles become more territorial, seeking out nesting sites and strengthening bonds with their mates. 

If you spot a gathering of large birds within the breeding season they may be juvenile bald eagles! Juvenile bald eagles can be identified by their mixed brown/black and yellow beaks and brown to brown and white speckled heads and tails -  as bald eagles do not sport their white heads and tails until they are mature at age 4 or 5 years old. Since they are not yet ready to claim territories or breed, they tend to be more social and may congregate in areas with abundant food. You might see them near rivers, lakes, or coastlines where they can scavenge and practice hunting skills. However, once they reach maturity they start becoming more territorial and seek out nesting sites of their own.

Nesting & Mating Behavior 

In Maine, bald eagles are already nesting with their partners and preparing to lay eggs in early April! While many of Maine’s pairs have already completed their courtship and bonding activities you may still have time to spot them nest building. Keep an eye out for eagles flying past carrying sticks, moss, and other materials. They nest in tall trees near water sources. For our area you will typically find them nesting in large white pines. These nests can reach up to 10 feet wide and hundreds of pounds, as they rebuild on the same nests year after year. 

Both parents take turns incubating the eggs, however, females spend more time in the nest while males are more often hunting and returning with food for the brooding female. Once eggs hatch, bald eagles will care similarly for their young for 16 - 20 weeks until they fledge. This leaves a lot of time for birders to try spotting young before they are able to fly off!

If you frequent Pushaw stream you may know that there is a large eagle nest off to the side just after you paddle past the route 43 bridge. Although we didn’t observe it in use last year—having reached the area only in late May—there’s a good chance it was active and may continue to be used this year. Either way it is fun to try and spot the nest as you paddle by!

Where Are They Now? 

Although the large gatherings of bald eagles have dispersed, many still remain in our area. Keep an eye out for them along rivers, near lakes, and soaring above forested landscapes - maybe drop by Hirundo and see if you can locate our resident eagles! If you spot one, take a moment to appreciate the incredible recovery of this species and the dedication of those who worked to protect it.

Sources:

Bald Eagles. Bald Eagles: Raptors: Birds: Species Information: Wildlife: Fish & Wildlife: Maine Dept of Inland Fisheries and Wildlife. (n.d.). https://www.maine.gov/ifw/fish-wildlife/wildlife/species-information/birds/bald-eagles.html \

Bald eagle. (n.d.). https://www.fws.gov/sites/default/files/documents/bald-eagle-fact-sheet.pdf 

Bald Eagle Overview, all about birds, Cornell Lab of Ornithology. Overview, All About Birds, Cornell Lab of Ornithology. (n.d.). https://www.allaboutbirds.org/guide/Bald_Eagle/overview 

McPhaul, M. M. (2019, December 23). How bald eagles weather Winter: The outside story. Northern Woodlands. https://northernwoodlands.org/outside_story/article/bald-eagles-weather-winter