Photo courtesy of the National Wildlife Federation

Find loon count data for your lake:

Go to the "Lake Search" page (PEARL Home > Data > Lake/Stream Name). Enter the lake name to access the "Lake Overview" page for your lake and then click on the "Loon Counts" button.

Information about loons on this page:

• General Information
• Threats to Loons in Maine
• The Maine Loon Count
• Links to More Information on Loons

General Information
In Maine we are lucky to have a rather high population of loons, compared to states to our south and west. Of the five loon species found in the world, only the common loon (Gavia immer) breeds in Maine. The summer range of the common loon extends across northern sections of North America and Greenland. The winter range stretches along the east and west coasts of the continent, as far south as the Gulf of Mexico.

Common loons are large birds, measuring almost three feet from head to tail. Their wingspan is almost four feet, and they can weigh up to 14 pounds. Unique adaptations of the loon include their solid bones (most birds have hollow bones) and their large powerful legs located at the far rear of their bodies (they can not walk on land easily), both which make them superior divers, allowing them to hunt underwater for their food. Loons feed primarily on fish, which they hunt for by sight, so water quality is very important to their success. They usually eat fish that are less then eight inches long and prefer species such as yellow perch, suckers, bullheads, and sunfish. If fish are not available, they will also forage for insects and crustaceans.

Male loons usually arrive on lakes in Maine very close to the day of ice-out in the spring, arriving earlier than the females to establish and defend their territory. Territories range from 20 to 200 acres of water, with the average about 100 acres. Breeding loons usually return to the same lake year after year on or near the lake they were raised on. After successful breeding, the female will produce 2-3 mottled brown or green eggs. In Maine, loons usually lay their eggs between mid-May and mid-June. Both the male and female incubate the eggs for approximately 29 days until the chicks hatch. This incubation period is when loons are most sensitive to human disturbance. If the disturbance is great enough, the pair may abandon the nest and eggs. After hatching, the chicks will stay with their parents until they can successfully fish and fly (usually 10-12 weeks). If healthy, loons usually live 25 - 30 years.

Threats to loons in Maine

Human Disturbance
As development on lakes in Maine continues, loons have to compete with humans for habitat. Because loons cannot walk well on land, they must build their nests on the shoreline so that they can easily slip into and out of the water. Nests on the shoreline are therefore susceptible to damage from wave action of boats and major fluctuations of water levels (especially on lakes controlled by dams). Loons may also become disturbed by humans traveling too close or for long periods of time in their nesting area. Other hazards to loons include discarded fish line, which they may become entangled in, and lead sinkers, which are toxic and may cause death.

Mercury
Many Maine lakes have high levels of mercury. Mercury is released into the air or water as a byproduct of combustion or improper waste disposal. New England has such high levels of mercury contamination because much of the pollution produced by coal burning power plants and industrial plants in the Midwest travels eastward with the jet stream and is deposited on the land and water bodies of the northeast by precipitation and dry deposition (dust that falls out of the air). In aquatic systems, mercury is converted to methylmercury that it is consumed by living organisms and moves up the food chain. Two characteristics of methylmercury make it so dangerous to living organisms, and to loons in particular. The first is that the chemical builds up in a body over time (called bioaccumulation). Longer living organisms such as loons suffer greatly from bioaccumulation. The second characteristic of methylmercury is that it increases in concentration when one organism eats another (called biomagnification). As a result, very small amounts of mercury in the environment can result in extremely high amounts of mercury in animals at the top of the food chain, such as loons.

Scientists at the Biodiversity Research Institute, based in Gorham, Maine, are studying ways in which mercury is affecting the health of loons and loon populations over time. So far, research suggests that mercury can have adverse effects on loons by causing changes in their behavior, reproduction, and body chemistry. These scientists are also studying other birds and animals to understand better the impacts of mercury pollution across the northeastern ecosystem. Visit the Biodiversity Research Institute website for more information on mercury pollution.

The Maine Loon Count

Beginning in the 1970’s scientists and naturalists in New England noticed an apparent change in populations of loons, but they had no data to verify this observation or monitor changes through time. For this reason, the Maine Department of Inland Fisheries and Wildlife and the University of Maine developed a method to estimate and monitor birds with a volunteer program managed by Maine Audubon. The first year of the count in Maine was 1987, with 100 lakes surveyed by volunteers on lakes. Another 100 lakes were added to the count by using aerial surveys. Today, Maine has over 1,050 loon counters participating in the program.

Data collected so far has shown population growth in southern Maine since the count started, from 1,800 adult loons in 1983 to around 2,500 in 2000. That growth rate seems to have stalled, with an average of 2,500 adults counted in the last three years (as of the 2004 count). The chick rates have gone up and down from year to year since the count started, with the average around 200. This type of data begs several unanswered questions, such as: Are more loons breeding, and chick survival is actually decreasing? Is the breeding population staying the same, with the number of counted adults representing ‘bachelor’ loons who do not have territories and are not breeding? These and other questions continue to push scientists to develop a better understanding of this precious species.

To find loon count data for your lake, use the search mechanism located at the top of the page. To find out more about the loon count program, contact the Maine Audubon Society.

Links to more information on loons in Maine

Maine Audubon
Find out about the Maine Loon Count program and access more detailed information on loons in Maine.

Biodiversity Research Institute
Find unique and valuable information on the effects toxic substances such as mercury on wildlife in the northeast and learn more about loon monitoring programs. Also, be sure to checkout the “Loon Cam” that lets you observe the process of actual loons in Maine nesting, incubating eggs, and hatching chicks.

Resources:
Evers, David C. 2005. Mercury Connections: The extent and effects of mercury pollution in northeastern North America. Biodiversity Research Institute. Gorham, Maine.

Gallo, Susan. 2004. The Maine Loon Project: Today and Tomorrow. Habitat. Winter 2004. Maine Audubon. Falmouth, Maine .

Hooper, Bob. 2001. The Common Loon. Maine Audubon.

Maine Audubon. 2004. Volunteers Make 20 Years Count for Maine Loons. Habitat. Winter 2004. Falmouth, Maine.