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Upper Midwest Environmental Sciences Center


Loon Study - Frequently Asked Questions


Which state has the most common loons?

In the continental U.S., surveys indicate Minnesota has the largest population of common loons with more than 10,000 adults. Wisconsin has an estimated summer population of about 4,000 adults. Additionally, states with breeding populations include Maine with approximately 4,100 adults, New York with more than 800 adults, and New Hampshire with about 500 adult common loons.

How long each year do common loons stay within their summer (breeding) range?

map of summer/winter loon range

Loons return to northern forested lakes and rivers in the springtime, usually in April or early May. The breeding range includes Alaska and much of Canada south to portions of Washington, Idaho, Montana, North Dakota, Minnesota, Wisconsin, Michigan, New York, Vermont, New Hampshire, and Maine.

Breeding loons, like those radiomarked in this study, leave breeding areas in late October to early November.

Loons spend the winter season along the Atlantic, Pacific, and Gulf of Mexico coasts. Some loons winter on inland reservoirs.

How far can common loons fly in one day?

In one documented case, a loon traveled 670 miles within a 24-hr period. In another case, a loon traveled distances of 360 and 505 miles during two consecutive days. All of these flights were likely single movements.

What is the farthest a common loon has flown in one migration?

The distance between breeding and wintering grounds of the loons we monitored in Minnesota and Wisconsin ranged from 1,170 to 1,570 miles.

Do common loons return to the same place to nest where they were hatched and raised as chicks?

loon with eggs in nest

Extensive banding and observation of marked loons in northern Wisconsin has shown that loons first return to the breeding grounds at age 2-5 years, with males tending to return nearer to their natal territory than females. Both sexes tend to wander and use many different lakes as "floaters" for 2 to 3 years before settling. Males and females both show a striking age-dependent pattern in the means they use to gain a territory: when 4-5 years old, they usually settle in a vacant territory with a mate and thus found a new territory. If they have not acquired a territory by 6-8 years of age, however, they usually attept to seize a territory from an established owner after a violent and prolonged territorial battle. Such battles can be dangerous. In fact, about one-third of all territorial takeovers among males result in the death of the displaced male owner.

For additional information on common loon territorial behavior, visit The Loon Project website provided by Dr. Walter Piper at Chapman University.


Where do common loon’s nest?

Loon nests are usually situated on a low mass of vegetation near water, often on an island and usually contain two olive-brown, lightly spotted eggs. Both adults incubate the eggs and share in care of the young.


What is the difference in appearance between a male and female common loon?

Male and female loons are similar in appearance. Males are generally larger than their mates.

Seasonally, the adult common loon's plumage changes dramatically between the breeding and non-breeding seasons. The photo above which shows an adult on its nest is indicative of the loon's breeding (summer) appearance.


Why does the common loon chick ride on its parent's back?
How long does the loon chick ride on the parent's back?

Common loon chick

Biologists suspect there are two primary reasons for back riding:

  1. Back riding may serve to warm the chick.
  2. Back riding may reduce predation. During the first week after hatching a chick may spend more than half its time on adults. After a week there is a sharp drop in back-riding.


How long do common loons live?

Loons are a long-lived bird. The oldest known common loon lived 25 years but their lifespan may be up to 30+ years.

What do common loons eat?

Common loons feed primarily on fish, but also consume aquatic invertebrates (including crayfish and aquatic insects).

Why do common loons make calling noises at night?

Loon calls are used to communicate among family members and to maintain territories during the breeding season. Adult loons have four basic types of vocalizations; the yodel, hoot, wail, and tremelo.

How many different kinds of loons are there?

There are five recognized species of loons (family Gaviidae):

  • Common Loon
  • Arctic Loon
  • Pacific Loon
  • Red-throated Loon
  • Yellow-billed Loon
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