Two common loons swimming. Credit: Bob Duchesne / BDN

I live on a lake. Therefore, I have summer guests. They love the water. They love the scenery. They love the loons calling at night.

All night.

Geesh, sometimes the loons won’t shut up. For those who have a backyard robin, mockingbird, or Carolina wren waking them up before dawn every morning, don’t you wish sometimes you could just throw a shoe at them?

Every April, minutes after ice out, I look forward to the eerie yodeling. By August, not so much. It’s OK when they stay out in the middle of the lake, or on the far shore. But when they’re right outside my window, yikes!

I know I should be grateful. A lot of tourists long for this experience. In fact, Mainers should be universally proud of their loons. The population has nearly doubled over the southern half of the state. How do we know? We counted them.

Maine Audubon’s Loon Count happens annually on the third Saturday of July. During the highly coordinated event, more than a thousand volunteers fan out over assigned areas, and start counting at precisely 7 a.m. They count for half an hour, then stop. This timetable minimizes the chance that loons will be double-counted.

While all the loons get counted, it’s the number of chicks that matters most. Loons are a long-lived species, typically over 20 years. It can take years to observe changes in the population. By counting the chicks, reproduction rates can be compared year-to-year, showing trends much more quickly.

For a long time, the trends were worrisome. Half of Maine’s loon population had disappeared. The nesting range for common loons extends all across Canada, barely dipping down into bordering states. In Maine, there are multiple explanations for the decline. But what about all those undeveloped lakes in northern Ontario? It didn’t take long to identify mercury and acid rain as the chief culprits, diminishing food supplies and decreasing reproduction. Loons were simply unable to make enough babies. Better pollution controls reduced the threat somewhat, and populations have rebounded a bit, but our lakes have not fully recovered.

Along the southern end of the loon’s range, additional threats have contributed to the decline. Lakeshore development reduces nesting habitat. Harassment by watercraft disrupts breeding. Boat wakes from speeding watercraft swamp nests. Many adult loons are poisoned by ingesting lead sinkers while picking up gravel from lake bottoms.

Today, we’ve become more sensitive to these threats. Not only has harassment decreased, but people are more eager to report violators. Maine has phased out the smaller lead sinkers, and Maine Audubon has even partnered in free exchange programs to help anglers switch from lead to acceptable substitutes. Anglers are more careful when discarding spent fishing line.

However, some threats have increased. A resurgence in the bald eagle population has led to more predation on loons. The illegal introduction of non-native fish, especially northern pike, has increased the predation threat to chicks. If you ever wondered why loon chicks ride on the backs of their parents, it’s because of the threat from below, including snapping turtles.

This year marked the 38th annual loon count. The final results won’t be fully tallied for another few months, but results from last year show the news is mostly good. We’re back up to around 3000 common loons in Maine. The population appears stable, and it’s even growing slowly. There was a noteworthy decline in the adult population over the last two years, but temporary fluctuations are normal. Sometimes, the reduced number is just because of bad weather, and fewer reports on count day. This year’s count was hindered by fog.

Maine is doing its part to restore the species, so I guess I’ll have to live with occasionally interrupted sleep. Songbirds are noisy in spring, but quiet down as summer advances. Not so for loons. They can be darn talkative right up until the lake freezes. They have a complex language, and their conversations change over the months. Loons typically mate for life, so for much of the early season they just call to each other, getting reacquainted and romantic. The males also yodel to warn other loons to stay away. Later, the pairs call often to let each other know where they are, since more than a mile can separate them while feeding. Both will call out threats, which mostly consist of eagles and floatplanes. Eventually, the males stop defending territories, and loons congregate wherever the fish are. I just hope those fish aren’t outside my window.

Bob Duchesne, Good Birding

Bob Duchesne serves as vice president of Maine Audubon’s Penobscot Valley Chapter. He developed the Maine Birding Trail, with information at mainebirdingtrail.com. He can be reached at duchesne@midmaine.com.