A common loon stretches its wings on Little Long Pond on Mount Desert Island. Credit: Aislinn Sarnacki / BDN

Hearing the haunting call of a common loon echoing across the water can be exhilarating.

And it can happen frequently, as we boast the largest population of loons in the Northeast, according to Maine Audubon.

However, boaters, anglers, paddlers, campers and others who recreate in Maine waters also pose the greatest threat to the state’s loon population. They are often killed by being struck by watercraft, ingesting or becoming entangled in fishing equipment, or having their nests disturbed by excessive wave action caused by boaters or from altering shoreline habitat.

Loon behavior can tell us a lot about how the birds are doing at a given time. That’s why it’s important to recognize some of the key signs that indicate a particular activity might be disturbing these majestic birds.

The Maine Department of Inland Fisheries and Wildlife suggests that bird watchers observe loons from a distance through binoculars or a spotting scope.

That’s because loons are averse to interacting with people or when approached by watercraft and may abandon behaviors such as feeding their young or sitting on eggs in a nest, if they are disturbed.

If you’re getting too close for the birds’ comfort, they’ll probably let you know.

Here are some loon behaviors that will tell you to back off.

Signs of agitation include a loon performing the “penguin dance,” in which the bird seemingly stands up in the water and approaches you in an aggressive way. It also might make its “yodel” call, which males use to defend territory.

Also be aware if a loon vocalizes in response to your proximity to it. The “tremolo” call often is the result of an annoyed or alarmed bird.

Should you happen to see a loon on the shoreline that is lying down and also has its head down, the means it is tending to a nest. Do not approach. It may slip back into the water, which leaves the eggs unattended and vulnerable to predators or weather.

July and August are particularly important months for Maine loons, which are transitioning into family-rearing mode. Eggs are incubated in the nest for approximately 27 days, at which time they hatch.

The loon family then moves to an area close by that serves as a nursery. The adult birds spend considerable time catching fish to feed the chicks.

Sometimes, you might see some of the little ones riding on the backs of their parents, where they are able to stay warm and out of the reach of predators.

DIF&W said it’s often necessary to have a keen eye when observing two adult loons, as each might have one or two chicks along for the ride.

Even so, loon chicks don’t need a lot of time to get up to speed on life as a busy aquatic bird. According to Audubon, chicks leave the nest in the first day or two of life and are capable of diving and swimming underwater within two or three days.

It takes about 10 or 11 weeks before chicks are able to fly.

In the meantime, they’re susceptible to predation, according to the National Wildlife Federation. Even though adult loons are seldom hunted — except possibly by sea otters during the winter, and bald eagles and ospreys — eggs and chicks must be protected.

Maine has many laws in place to help protect loons and other wildlife on our lakes and ponds. They govern the use of boats and fishing gear, along with property alterations.

Boaters are prohibited from harassing, chasing or disturbing wildlife, and watercraft must travel at or under headway speed and leave no wake within 200 feet of any shoreline.

Personal watercraft are not allowed on some lakes and ponds.

Maine has had a law since 2013 that prohibits the use or sale of lead sinkers that weigh one ounce or less or are not more than 2 1/2 inches long and in 2016 also banned the use of bare-headed jigs of those same measurements.

A 25-year study previously determined that ingestion of lead fishing equipment was responsible for approximately one-third of all adult loon deaths in the state.

Pete Warner

Pete graduated from Bangor High School in 1980 and earned a B.S. in Journalism (Advertising) from the University of Maine in 1986. He grew up fishing at his family's camp on Sebago Lake but didn't take...