News & Notes

Should I build a loon nesting platform?

Tuesday, July 24th, 2012
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Loon nesting on an man-made nesting platform. Photo by Turner Ragsdale

There’s not much to a loon’s nest, just a simple mound of vegetation and muck scooped from the water’s edge. Loons nest right beside the water so they can slip on and off the nest easily, quickly, and quietly, without being seen by predators. When all goes well, a loon pair will incubate their eggs for about 29 days, then leave with their newly hatched chicks to spend the rest of the summer on open water.

But often, in Maine, things don’t go quite like that.  Heavy rainfall in early summer, like the June rains of 2012, can lead to rapid water level rises of a foot or more. The eggs sitting atop a loon nest can simply float away.

But loons have options.  They can start over again if their eggs disappear, remounding vegetation, often fairly close to the first nest site.  And if the rainy June evolves into a dry July, the loons will be able to keep the next batch of eggs warm and dry.  But even with moderate weather, keeping lake water levels constant can be an issue, especially if dams on the lake are adjusted to raise and lower water levels throughout the breeding season in June and July.  This is the case where a man-made loon nesting platform makes the most sense, and where they are likely to get the most use.

Here are some quick thoughts, tips, and links on loon nesting platforms that will help you make an informed decision about putting one out on a lake or pond near you.  See the platform links below for much more detailed information on raft construction.

If a lake has loons that breed successfully, year after year, a platform will not likely be used.  Platforms can be a good management tool when changes in water level, or persistent mainland predators, result in egg losses year after year.  We suggest you watch a loon pair for a couple of years, documenting where their territory boundaries are, where they are attempting to nest, and if they are successful at hatching out eggs, before deciding to place a platform. Loons are never 100% successful, and an occasional loss of an egg may not warrant placing a platform.  Consistent losses of eggs over three or more years, due to predation or water level changes, makes a good case for experimenting with a platform.

Making and maintaining a nesting platform is a serious investment of time and money.  Take a look at “traditional” cedar raft plans as well as plans for an “eternal” platform design from Wisconsin.  Whatever route you choose, platforms need to go in the water early in the season, as close to ice out as possible.  Loons start defending their territories and looking around for nest sites as soon as they return in early spring.  The sooner the platform is out, the greater the chance that it will be seriously considered by loons as a place to nest.  Platforms need to be securely anchored to the lake bottom, and watched throughout the summer to make sure they stay put. Putting platforms in quiet coves, away from wave action and in deep enough water that they will not be stranded if water levels drop, will improve chances of success.

It can take up to three years for a loon pair to use a loon platform, so patience is required!  Don’t give up if the loons don’t immediately take to the platform.  They are likely checking it out, and evaluating how good a nest site it might be.  Keep putting the platform out in the spring (and taking it in in the fall), and give it at least three years to see if it works. If after three years the loons are staying away, there’s probably something not right with the location.  Or they may just not like it.  See the raft plans for more details on good raft locations.  If loons are successful on natural nest sites, they may never change to the platform.

Never place a loon nesting platform without having a rough idea of where loon pairs are on a lake.  Drawing in a new loon pair, or causing conflict by placing a raft between two existing territories, can do more harm than good, and can cause additional nest failure, exactly what you are trying to avoid with the platform in the first place!

For much more detailed information about the science behind raft placements, read Chris DeSorbo’s 2008 article in the Northeastern NaturalistFor printed copies of raft plans, e-mail [email protected].   And as always, visit the Maine Loon Project home page for more information about loons in Maine.