Laura Erickson's For the Birds

Loon nest structures

Last month I had the opportunity to drive to Ithaca, New York, to attend an ornithological meeting at the Cornell Laboratory of Ornithology. This was my first visit ever to this wonderful place, where so many of the world’s greatest ornithologists have been trained, or conduct research, or contribute to the amazing collection of sounds, films and videos. I felt as if I were on a pilgrimage to my own personal Mecca.

Not only did I get to spend time walking about in this splendid facility, I also got to meet a host of wonderful ornithologists, including one man whose work I’ve admired greatly—he’s shared some of his data and loon recordings with Journey North, the Internet site that teaches kids about migration. Jay Mager is a Cornell University graduate student who has been studying loon vocalizations and territorial behavior in northern Wisconsin. I’ve used his stuff on Journey North because he gave us recordings and sonagrams to show how he identifies individual loons by their calls. At this meeting in Ithaca, Jay was showing some of his research about floating loon nest platforms. When properly constructed and spaced, these structures are wonderfully beneficial to loons, giving them secure nest sites that are safer from predators than natural sites, especially on disturbed or developed lakes. If anchored properly, with enough slack, they can stay afloat even when water levels rise significantly, so loon nests on these are much less likely to get flooded than loon nests on shorelines. Perhaps that is why loons are so drawn to them.

Directions for building a loon platform can be found in Carrol Henderson’s excellent book, Woodworking for Wildlife. In both Wisconsin and Minnesota, these structures need to be registered because they can be a serious hazard to boaters in some situations. Carrol Henderson recommends putting reflectors on all four sides, too, to make them more visible to boaters at night.

But as Jay Mager has learned, loon nest platforms are a perfect example of how it’s possible to have too much of a good thing. Loons are highly territorial, probably because it takes so many fish to sustain a pair and their two chicks over the summer, and until the babies can fly in fall, they’re pretty much restricted to their lake. If fish populations get depleted, the young loons can easily starve, or have to walk clumsily in search of another lake. So for the best insurance that a loon family won’t run out of fish, a pair of nesting loons drives every other swimming bird from their lake. Usually the more experienced pair at a given lake wins the fights quickly and without much damage to any of them because in natural situations, the “new kids on the block” readily give up and search for another lake. Unfortunately, loon nesting platforms are so enticing that newcomers to a lake seem more likely to stand their ground and fight. And loons fight to win. When two pairs are competing for the same lake, they can injure or even kill one another. Jay showed me a video clip of one amazing fight, with the birds locking bills and jabbing at one another—it was pretty gruesome.

Because nesting success of loons is significantly helped when they use nest platforms, Jay is not recommending that people stop providing them. But until research gives a clearer picture of the best spacing for loon nest platforms, it seems prudent for us to never allow more than one of these structures to be built on a single lake. That means property owners on lakes need to cooperate in providing these, or risk doing more harm than good.

People who care about loons have made great contributions that are helping this magnificent bird. Making sure we aren’t putting more than one loon nest structure per lake is a small step backward for us humans, but may prove to be a giant leap for loonkind.