The Return of Bald Eagles to the Whites
Bald Eagles have become a relatively common sight around our local waterways and are often seen hunting over Conway Lake, Chocorua Lake, and the Saco and Swift rivers. Tin Mountain Outdoor Center takes a closer look at the driving factors behind the return of bald eagles to the region.
By Matt Maloney, Tin Mountain Outdoor Center
The bald eagle is a striking bird of prey that inspires awe amongst those who spot one soaring high in the sky or swooping its talons into the water to bring up a fish. Few birds generate such excitement from young and old, birders, fishermen, swimmers, and sunbathers alike. While we know the eagle as our national symbol, its presence goes beyond national pride and represents wild places to so many. Floating in a canoe or kayak near a tall pine on a lake shoreline, it’s quite a scene to suddenly be startled by the whooshing wing beats of a bald eagle, its magnificent wingspan in full detail, and the striking white head confirming a close encounter with an eagle.
Among the ever-present White Mountains and the broad valley of the Saco River, there are scattered lakes and deep ponds that support a population of bald eagles in the Mt. Washington Valley. This was not so very long ago.
As recently as 1988, there was not a single known nesting pair of bald eagles in New Hampshire. There hadn’t been a known nesting pair in 40 years! While once relatively common on lakes, rivers, and seashores throughout New England, bald eagles went into a severe nationwide decline in the 1940s through the early 1980s.
The bald eagle was officially recognized as the national symbol of the United States in 1782, but by 1963, there were only 417 nesting pairs in the country. One of the primary known reasons for this decline was the thinning of eagle eggshells. The thin eggshells would often break before hatching during incubation, and thus, populations plummeted over the years. The thinning of eggshells was eventually tied back to using the pesticide DDT, which was widely used and manufactured after World War II. Pesticides and other chemicals enter the food chain when they are present in the soil. Water runoff takes them into waterways, where they accumulate in plants and the fatty tissues of fish and other organisms. These pesticides accumulate and move up through the food chain. Bald eagles, like other birds of prey, sit at the top of the food chain and receive the greatest concentrations of pesticides in their tissues and bloodstreams. In turn, DDT has been found to interfere with the ability of eagle mothers to absorb calcium from their diet, resulting in less calcium availability for egg shells. A big problem.
DDT was eventually banned in 1972 and has slowly been filtering out of the environment and food chain ever since. Rachel Carson’s famous 1962 book Silent Spring was what first brought the problem with DDT and pesticide use to light for the general public, and the publicity it raised eventually led to congressional inquiries and further scientific studies of the effects of pesticides on food chains. Not long after the ban took effect in 1972, raptor populations began to slowly rebound, including an upward gain in eagle numbers that continues to the present.
We can thank people like Rachel Carson today when we see an eagle in the Valley, for it took lots of foresight and bravery to recognize and publicize the plight of these birds.
IDENTIFYING BALD EAGLES
Bald eagles have wingspans of up to 8 feet, so the only bird in our region with a comparable wingspan is the turkey vulture. Turkey vultures soar with their wings in a bit of a V formation though, while eagles soar with flat wings. This is a great diagnostic marker when seeing them soaring from afar.
Like all raptors, bald eagles are sexually dimorphic, with females weighing more than males. A typical adult female eagle is 14 pounds while males weigh between seven and 14 pounds. I will use the term eagle to describe bald eagles throughout this article, although it should be noted golden eagles migrate through this area from time to time on their way to nesting grounds in Quebec and Labrador.
A golden eagle can look like a juvenile bald eagle, except for the golden feathers on its nape, the back of its neck. Immature bald eagles, even after they reach full size, will have a black beak, and brown and tan feathers. They reach maturity at three or four years, at which time they will grow the distinctive white feathers on their head and their beak will turn yellow. Bald eagles typically live 15 to 20 years in New Hampshire.
Know how to Identify birds in flight
Left to right: osprey, turkey vulture, adult bald eagle, subadult golden eagle
Bald eagles are built for soaring, with long broad wings, large wing slots, and broad, wedge-shaped tails. They hold their wings flat in flight, migrate during the day, and use wind corridors—geographical features that concentrate and amplify wind—whenever possible. A stiff tailwind will send migrating eagles aloft in the thousands, especially over surfaces with little opportunity for thermal soaring. The bald eagle body plan and low-aspect wings—i.e. large, broad wings relative to its overall surface area—are most suited to low-angle, low-energy soaring flight.
SOURCE: The Raptor Resource Project • www.raptorresource.org
WHERE TO SEE THEM
How do you find bald eagles? Go to the water! Most soaring eagles are seen near major water sources such as Conway, Silver, and Ossipee lakes or slow-moving rivers such as the Androscoggin River north of Pinkham Notch. Fast-moving mountain streams and rivers, such as the Swift River, are not typically utilized by eagles.
Bald eagles typically hunt for fish as their dietary mainstay, although they will also prey on waterfowl and scavenge carrion. Sometimes they will even steal fish from other birds such as ospreys. Bald eagles also prey on waterfowl such as loon chicks, making them “a problem for loons,” according to Chris Martin, a biologist with New Hampshire Audubon who coordinates New Hampshire’s eagle monitoring program. However, if the loon population is healthy, it should be able to withstand the occasional loss of a chick. Martin noted that there is little overall effect on loon populations on a statewide level due to eagle predation.
Bald eagles have become relatively common sights on our local waterways and are often seen hunting over Conway Lake, Chocorua Lake, and the Saco River. Within New Hampshire, their nesting stronghold is in the Connecticut River Valley, the Lakes Region, the Great Bay estuary, the Merrimack River Valley, and the Connecticut Lakes Region at the top of the state. There are fewer lakes and ponds in the Conway Region than in other parts of the state with higher nesting numbers, but there is habitat here, as eagle habitat is essentially wherever healthy, fish-populated water is found with tall trees nearby for nesting.
Like all animals that feed at the top of the food chain, bald eagles are vulnerable to toxins in the environment or changes in the population of their prey, fish. As mentioned, this was evidenced by the use of DDT in the past. Fortunately, bald eagle populations are still growing each year throughout New Hampshire. In 1989 a bald eagle pair nested on Lake Umbagog, the first New Hampshire nest record in 40 years. There was a single breeding pair in New Hampshire on Lake Umbagog right through 1997. Then the population jumped and by 2014 there were 41 breeding pairs in the state. There were 59 pairs in 2017. Last year in 2022, there were 72 observed nesting pairs and 92 pairs exhibiting territorial behavior. Quite a comeback it has been, indeed.
MONITORING LOCAL EAGLES
Bald eagles are monitored in the state by New Hampshire Audubon, through a contract with New Hampshire Fish and Game. Among the statistics recorded are total nesting pairs and overwintering numbers. One of the interesting things about nesting eagles, as noted by Martin, is that all adult eagles in the state that showed territorial behavior during the nesting season stayed on their territories through the winter months. According to Martin, even if eagles lose access to consistent open water, they will scavenge, expand their range, and use their experience garnered from finding food sources in the past to get through the winter months, even in the very cold Connecticut Lakes Region. Some eagles are good at utilizing ice fishing locales for scavenging on bait fish and food scraps left by ice fishermen. Younger birds without territories may have to travel to find food, often congregating around open water areas, such as those found below dams or in seashore locales such as the Great Bay estuary or traveling further south. So, if you know of an eagle nest near you, those breeding eagles likely remain around all winter.
LOCAL NESTING EAGLES
The nesting period for eagles starts around mid- to late-February and eggs are typically laid around March or April, with chicks hatching out about a month later. The more “experienced” an eagle is with nesting, according to Martin, the earlier in the season it will start the nesting process. The chicks will be covered in white downy feathers and fed fish in a large nest made of sticks, high up in a tree overlooking the water. These nests are often used from year to year and grow bigger and bigger over time, often becoming mini fortresses as seen from the water level. Chicks are full-sized eagles, with juvenile plumage, and ready to fledge between mid-June and August typically, taking 12 weeks to reach full size. It’s a good sign of a nearby nest if you see a full-size eagle without adult plumage making food cries in the summer months.
As much as it is a thrill and an honor to see a bald eagle up close, we can’t take their comeback for granted. These efficient predators are, perhaps, still rebounding from the reproductive losses caused by DDT in the food chain. At some point, they will reach population equilibrium and we may forget or discount their other needs, such as habitat, healthy waters and food chains, and lack of disturbance from humans.
Increasing home building on lake shores could potentially affect nesting sites. The vast majority of nest sites of bald eagles in New Hampshire are on private lands. This shows a healthy population range, which reflects the nature of land ownership in New Hampshire. Bald eagles are a protected species; they can’t be hunted, but landowners need to be aware of potential eagle nesting habitats if they own waterfront property. Lead toxicity (which is usually fatal) from swallowing fishing sinkers, predation from raccoons on eggs, road kills (when feeding on carrion), and mercury are still threats and lead to some mortality. One study in Maine found low to moderate levels of mercury in most nesting eagles. (DeSorbo et al. 2009). Mercury is a neurotoxin that moves up the food chain, mostly originating from emissions fallout from coal-burning power plants.
YOUR HELP IS NEEDED
Help is needed monitoring eagle populations throughout New Hampshire, and Martin says the Conway area could use more monitoring and volunteers. See the previous page for information on lakes in the area that have nesting eagles, and what residents and waterfront owners can do if they are interested in helping Audubon monitor populations and nest sites in the area.
Tin Mountain Conservation Center
TMCC is a nonprofit environmental education and conservation organization, providing programs for children, families, adults, and communities that create greater awareness and understanding of the natural environment. Since 1980, the center has offered hands-on programs in schools, at summer camps, and within communities throughout northern New Hampshire and western Maine. Tin Mountain fosters future generations of environmental stewards and responsible outdoor enthusiasts. Bald Hill Road, Albany, NH • (603) 447-6991 • www.tinmountain.org
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New Hampshire Audubon Needs Your Help
Biologist, Chris Martin, with New Hampshire Audubon, coordinates the tracking of populations of nesting eagles in New Hampshire. According to Martin, there is some good nesting habitat on Conway area lakes and lots of sightings, but very little info on confirmed nest sights.
Conway Lake has a confirmed nest, but other lakes and ponds need more eyes to help Audubon figure out if there are undocumented nests. Bald Eagles are consistently seen on Chocorua Lake and Silver Lake, for instance, but there is not a confirmed nest at either locale.
The lack of nesting records, according to Martin, shows a need for more volunteer observers. If you live near an eagle nest or see a suspected eagle nest, please contact Chris Martin at (603) 224-9909 ext 317, or send an email to email@example.com