The Loon is the state bird of Minnesota. 
They are a fascinating bird that is generally found in abundance only in clean pristine lakes.

They live in abundance in Minnesota state parks near the Boundary Waters Canoe Area Wilderness lakes.

The Loon call is synonymous with the true outdoors for many people.

Loon Calls

Audio Loon Calls

More Audio Loon Calls

The high, haunting wail helps loons to figure out where they are relative to each other.
They call back and forth, using the location of the sound to move closer together. 
The wail says "I'm here, where are you?  The other one calls back "I'm over here".

The wavering tremolo call—sometimes called the loon laugh—
means a loon is excited or alarmed.
Loons also use the tremolo when they fly over a lake
to announce their presence to any loons there.

A loon gives a hoot—a soft, short call—that sounds like the word "hot"
to let other loons know where it is or to ask another loon where it is.
A parent might hoot to its chick, or one of a pair to another.

Only male loons make this loud sound,
which starts with three notes and ends with a couple of swinging phrases.
They use it to defend their territory.
Each male has a “signature” yodel.
Some people can recognize a specific loon by his yodel.

We once heard a Yodel at around 3:00 AM and it was amazingly creative and beautiful.  I've never heard another yodel like that one since.

The YouTube videos found below remind me of experiences we have had during
Minnesota State Park camping trips.

Loon Wail

Loon Tremelo

YouTube Video

YouTube Video

Minnesota DNR Brochure on Loons
Easy to read brochure on Loons

Fascinating Loons, a book by Stan Tekiela
Truly a Fascinating books on loons with amazing facts

Loon Preservation Organization
Beautiful photos of Loons!

Stan Tekiela's Website
Pocket books for hiking and identifying wildlife for birds, flowers, trees, animals, etc