Recently I received an e-mail from Sharon Smith, in Monroe, regarding common loons. She has watched them from her family’s camp on Sebec Lake and has come to be familiar with their habits and behaviors. She noted they did not produce young this year.

“Not unusual, I know,” she wrote. “They say the water levels of the lake have fluctuated a lot this spring. What I’m curious about is the fact that the other morning I saw seven loons gathered together – isn’t it unusual for them to be gathering at this point in the season?”

I thought about that and began investigating. At the beginning of their nesting season, loons will define and defend a territory from each other as well as other birds, such as common mergansers. This defense increases as the chicks leave the nest and begin following their parents. Toward the end of the of the summer and into the fall, they stop defending territories and begin congregating in large flocks, or “rafts,” prior to migrating. This is common at this time and most people expect to see it.

However, there may be other times during which loons may associate without territorial posturing. Large bodies of water such as Sebec Lake, which is 6,803 acres in size (loons may hold territories of 20 acres or more), may have two, three, or more pairs nesting and holding territories. If the area is large enough, there may be designated neutral zones in which the loons associate without strife, as stated in the “Stokes Guide to Bird Behavior,” by Donald and Lillian Stokes.

My research also revealed loons that fail to reproduce successfully may stop defending territories earlier than usual; in this case they gather together in loose aggregations, feeding and socializing. This could be the case based on Sharon’s observations.

Additionally, I’ve gleaned from information in the “Birds of North America,” species accounts that loons may use certain lakes as nonterritorial feeding areas. I also corresponded with Maine Audubon biologist Susan Gallo, who coordinates Audubon’s statewide annual loon count on the third Saturday in July.

“When pairs aren’t breeding, they will congregate… and given no young on the lake, it may be pairs who abandoned attempts to breed, or it could be just non-breeding adults who are gathering where there are no territorial pairs to disturb them,” she said.

There are many factors that may prevent successful reproduction. Because loons build their nests so close to the shoreline, fluctuations in water levels can have disastrous effects. Rising water can swamp the nest and eggs. This also happens with boat wakes, so it is vitally important that boat traffic slows down when close to shore.

Falling water levels of even one foot can prevent a loon from reaching its nest. Since they are specialized diving birds, their legs are set far back on their bodies for maximum propulsion through the water, and are not able to support them on land. The best they can do is push themselves along on their chests. They also cannot take flight from land; aquatic takeoffs are possible only when a loon has sufficient room to gain enough speed and momentum for liftoff. Collisions with speeding boats and other personal watercraft is one of the leading causes of death for loons, according to Maine Audubon. I once read a horrible account of a jet skier who ran right over a nest containing eggs and young.

In addition, canoeists and kayakers, intent upon getting a close-up view or photographs of loons, often separate parents from young or cause an incubating female to leave her nest. In each case the eggs/young become susceptible to predation and exposure to the elements.

A new brochure detailing ways to avoid stressing loons is available from Maine Audubon. You can also help loons by getting involved in this year’s loon count on Saturday, July 19 (Sebec Lake needs counters!) You may find more information about both by contacting Susan Gallo at sgallo@maineaudubon.org or by calling 781-2330, ext. 216.

Chris Corio, a volunteer at Fields Pond Nature Center in Holden, can be reached at fieldspond@juno.com