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Early fall means the loons are gathering


Loons081910.mp311.06 MB
Chel Anderson is a botanist and plant ecologist for the Minnesota Department of Natural Resources. She lives in Cook County and joins us periodically to talk about phenology or what’s going on in the woods right now. Welcome, Chel.
Anderson: Hi!
And as we edge towards fall, if we’re not already there, what are the loons doing? That’s always a big thing this time of year. Are they getting ready to migrate and when?
Anderson: Their lives are changing as well, and one of the really interesting aspects of loon interactions and behavior that is easy to observe at this late summer and through the fall, through September anyway, are social gatherings that loons have. They actually have these throughout the summer, spring and summer, but as the summer grows later and we get into fall, the amount of time that loons spend doing this and in these social gatherings and the numbers of loons that are a part of them really increases. So, whereas in the spring you might have, oh, maybe three to five loons at the most that get together and hang out in these social gathering groups, by this time of the summer you’re definitely getting up above that number at times and eventually, in the late fall when they’ve really left here for the most part, the adults, and have moved into what are their migration staging areas. So, this would be by sometime in October. Then, you can have loons in groups of 40 or more gathering like this, and they use this in a variety of ways during their migration. But, what’s going on basically is, as far as researchers have been able to figure out, is that loons use these social gatherings, these get-togethers on lakes as a way to reinforce their cooperative feeding behavior that they use pretty much only during migration, or especially during migration. So, what that really means or what to look for if you’re wanting to check this out for yourself, is to watch for adult loons in groups of more than three, five, and, as I said, as the summer gets later and early fall, it could be even more than that, spending time together. And, what they do is they come together, they form a circle, and they’ll actually swim in a circle. And as they’re swimming together in a circle, they’ll be doing these very ritualized behaviors of dipping their bills, which if you’ve ever watched loons, you’ve seen them do this head turning, where they just turn their heads back and forth, jerk swimming, it’s called, which is just kind of a dipping of their whole head and neck. They don’t really submerge, but they do that. As they swim in this circle together, they do those behaviors. And after everyone has been engaged in that activity for a few minutes, then one of the loons will initiate the next phase by diving, and that bird will dive and disappear, and the others will all dip their heads down and peer in the water with their heads down. For a little bit after that loon has disappeared, they’ll wait for a little while and then they’ll all dive while the first one is still underwater and then they’ll eventually emerge usually a little distance away in a little less perfectly configured circle and they’ll repeat this over and over and over again. And as they spend, as I said, more and more time at this, they’ll repeat it many, many times, they’ll spend not just a few minutes doing this, but hours doing this together, and researchers believe that it is a way to learn and practice this feeding behavior that they use as they migrate, also to reinforce their connections together and familiarize themselves with each other. Loons spend the vast majority of their lives feeding on their own. In the winter, they pretty much feed on their own. They just hang out all by themselves. In the spring, when they come back here, you know, it’s one or two. That’s it, because of the strict territorial boundaries that they have. They mostly just spend time alone, and the adults, of course, are separate, because one is watching the young or on the eggs when that’s happening, so they spend this time making these other connections that they’re going to need during migration. Apparently, the benefit of doing this is that once loons leave their territorial nesting grounds that they’re very familiar with and know where the good fishing is, right, because that’s where they spend all their time in the summer, and on their migratory routes, they can be in lots of unfamiliar places where they don’t know the good fishing. So, everyone benefits by having 15 or 20 or more pairs of eyes peering down through the water looking for these schools of small fish that they’re primarily using in migration, and getting everyone on the same track to go after these things. So, you as an individual can benefit as a loon by working together with everyone else to find these.
Well, while the adults are moving around in circles, where are the young ones?
Anderson: Yeah, well, if you’re an adult loon, you won’t start really being a big part of these social gatherings until your young loons are pretty much good to go in terms of feeding on their own. Young loons are gradually weaned away from being fed by their parents throughout the late summer and into the fall. And so, eventually, the adults just leave the young loons on their own and spend more of their time alone or in these social gatherings, and the young loons, like other young birds, are usually the last to leave, because it takes them a long time to get fit and ready to make the migration. They’re hardwired to know where to go, but, you know, they have to build up their musculature for this long flight, so you’ll see young loons in the fall practicing, trying to get up enough speed to take off, for instance, and doing little practice flights around and around to build up those flight muscles and then feeding, just to build up the reserves that they need.
Chel Anderson, DNR botanist and plant ecologist. Thanks for helping us understand what’s going on with loons this year.
Anderson: You’re so welcome.