Common Knowledge: Loons are driven off lakes by boaters. The literature from the 1970s and 1980s makes it clear that there was a reduction in loon populations on lakes that were previously more isolated, and have become more accessible, and suffered greater amounts of boat traffic. Boats cause several problems for loons, including a damaging wake, and presumably it is bad if a loon is run over by a boat. Generally speaking, though, this early literature seems mainly to say that loons like the quiet and isolation and are driven away by human business. One piece of literature I read from the mid 1980s states, and I paraphrase: “increasingly, loons have gown accustom to the intrusion of boats, but shouldn’t we ask ourselves, isn’t it better to have loons that live in their natural habitat of peace and quiet?”

Challenge: There is evidence that indicates a change in the need for loons to have an out of the way and quiet habitat, and certainly this is what I see in our local loons, who are happily raising offspring among a modest number of fishing boats, the occasional skier-dragging boat, and jet ski thingies. I’m sure that these boats distract and bother the loons to some extent, but my memory of the adirondacks in the 1970s is that lakes with boats tended to not have loons. That is clearly not the case with this lake.

What I do want to point out in particular is the assertion I refer to above: That even if the loons grow accustom to boats, don’t we still prefer the old kind of loon that didn’t like boats? I understand the sentiment that author is expressing . I would love to see far more lakes in Minnesota be inaccessible by car and to have no motorized boats. At the moment there are very few, and the average Minnesotan, when you suggest this to them, stares at you blankly like they have no idea what you just said. What is the point of a lake without a road? Minnesotans are only just now beginning to realize that if you divide up every bit of land into 120 foot frontage lots on lakes, eventually there will be nothing but houses (not even small cabins) on every single lake. It is almost too late to reverse this thinking here in Minnesota.

The problem with the statement, though, is that the original plan seemed to be to link loons, as a kind of large aquatic canary, to habitat preservation. But then the loons evolved (or changed in some other way) so the disappearance of the loons from a lake was no longer the indicator of habitat destruction and human encroachment on the natural world.

In general we have to be careful what “what if” models we use, because sometimes the reality underlying the model changes (or perhaps was never what we thought it was to begin with) and we are then left not only short one rhetorical tool, but perhaps with a tool that will work against us. “Never mind what those conservationists said! They told us the loons would all die if we built too many cabins and used too many boats! But look, the loons adapted to us! So, everything will adapt to us!!”

In the next installment: Miscellaneous other stuff. Don’t miss it!

In this installment of How the Loon Terns we will look at breeding success.

In this installment of How the Loon Terns we will look at breeding success.

Common Knowledge: When a pair of loons fails to breed, it is because they have lead poisoning. Last year the pair of loons failed to breed. I mentioned this to a bird expert … a trained ornithologist who is actually working part time on loon conservation and who works for a major research institution. We were chatting at an educational bird display event and she was showing off some raptors. She did not know that I was a scientist, loon-lover, blogger, but she did know that I did the lake/cabin thing. That is important context to what she told me. She indicated that lead poisoning was the reason, caused by hunters using lead shot and anglers using lead weights. The idea here is that when loons go down to the bottom of the pond or lake to get stones for their gullets, they often pull up these bits of lead. This significantly affects their health. When I suggested alternative explanations, she politely told me that no, it was the lead. “Trust me,” she said. “Sure,” I said. “Right,” I thought.

Now, I’m sure this is a real problem, and I support regulations against lead in hunting and fishing. In fact, I can’t believe we are still using lead. But I’m not so sure that lead was the issue here. The following observations argue against it:

1) Last year the lake was at its lowest in any one’s memory. Everyone’s memory is that the loons produce one or two offspring a year, but last year it was zero and the year before one. Last year was the lowest lake level, the year before the second lowest. The lake level determines the ecology of the bay including the inlets and shallows, and the extent of the marshes. A very large area that is normally shallow water became marsh last year, and the loons do not really forage in the marsh. So, the change in ecology should be considered as a possible factor. I’m not saying it is a factor, and I’m certainly not insisting that it is the factor. I’m just sayin’.

2) The loons live over rocky and gravelly substrate. If you grab stuff off the bottom, it will be sand with gravel (between rocks). While there is some duck hunting right in the vicinity that the loons nest, and there is lots of fishing around here (so I have no doubt that lead is a problem) this bay has a lot of non-lead gravel to offer. I hypothesize that lead is more of a problem in waters with little natural gullet-suited gravel.

3) As mentioned in point 1, the loons seem to always breed except that one year. I would think that if lead was a chronic problem with these loons there would be many years with zero and some with one offspring, rather than most with two and a couple with one (except this one year with zero).

I want to point one thing out that is very important: I noted earlier that one loon in the pair might have changed two years ago. That pair raised one offspring. Last year I did not see a change, and this year I did not see a challenge to the pair by an interloping loon, but this does not mean it did not happen. So, it could be that both adults in the pair are constantly being poisoned by lead, and when two longer-term loons are resident, they eventually have low success, but when one of the two is relatively “fresh” they have better success. Or, it could be that an interloper who takes over (say a female) for one of the pair could be from a place where more lead is consumed (a muddy bottomed pond where the lead shot is more likely to be consumed because there is not much gravel). And so on. My point being that my observations of what happens here on this bay may be only part of the lead poisoning picture.

I conclude that while lead is important, I’m being fed some rhetoric from the bird conservation people who want to emphasize the lead problem at the expense of adherence to the science. I don’t blame them. The average person has a hard time with nuance (I wonder why???) so they have to be beat over the head with simplified version of the facts. Many hunters or anglers may be quite willing to use uncertainty as an excuse for continued use of lead sinkers or lead shot. I do think, however, that this sort of zeal on the part of bird conservation people is fairly common and not generally a good thing.

Next: A look at boating and habitat loss.