Many scientific journals are trying to add some color. That is, amidst the dry, highly-condensed scientific analysis and interpretation that is their standard fare, they are sprinkling lively photos and vignettes. These science tidbits vary from one journal to another in form and length. But all are much easier — and more fun — to look at than run-of-the-mill scientific articles.

In the past decade, I had observed the increasing frequency of short, splashy stories from a safe distance. Now that I have got scientific writing figured out, why should I diverge from it? (Okay….this blog is a dramatic departure from scientific writing, but I have settled into a good groove, so I do not count it!) In mulling over the possibility of a little splashy piece, I was not sure: 1) what I might write up as a colorful little story, 2) whether such vignettes are likely to be read widely, and 3) how hard it would be to get one published. So for many years I made no effort to report a loon finding in this new format.

The hypothesis of “spotlighting” by loon parents with chicks changed my mind. Having stumbled upon Frontiers in Ecology and the Environment and read a few of their delightful little photos and attached stories, I thought: “Well, I could do one of those!” I was encouraged by the fact that my current “hot” idea, the spotlighting hypothesis, is perhaps the most exciting one I have ever had. When I made statistical findings that provided strong support for the hypothesis, I was just bursting to share them with other scientists.

Sad to say, sharing of a finding or hypothesis in the form of an “Ecopic”, as Frontiers calls their little photos/stories, is not a thorough and rigorous means of sharing. 250 words is simply too few to provide evidence in support of any idea. If you are a cynic, you might even claim that Ecopics and their ilk allow scientists to get their half-baked ideas out there without thorough scrutiny by their peers. Please take my word for it when I say that rigorous testing of the spotlighting hypothesis is very much on my mind!

Ignoring for the moment that not all is nailed down with regards to the spotlighting hypothesis, take a look at the Ecopic. My text and Linda’s photo tell a story that we had not dreamed of when intensive study of loon territorial behavior began 30 years ago. So for now, let’s put aside the uncertainty and simply enjoy what loons might be doing!

One of the challenges of studying loons is that they are so well-loved. Many people have observed them, written down notes about them, and — here’s the problem — shared their speculations about all aspects of loon biology with others. Those of us who study loons are in a position of power, because the public looks to us for information. It takes some humility, when a journalist asks us a question about loons, to admit that we do not know the answer. Admitting ignorance is embarrassing. It disappoints the questioner. It makes us feel inadequate and uninformed. Yet admitting ignorance is vital. Our willingness to say we understand fully some aspect of loon biology that we do not — on websites, at conferences and in print — poses great problems for loon science and conservation.

Wait. Published material on loons should help move our understanding forward, right? Yes and no. Well-researched, robust science on loons improves our understanding; anecdotal, speculative work based on small samples of loons, inexpertly analyzed, and passed off as fact does not. In the field of loon behavior and ecology, a huge “grey literature” exists, which consists of popular loon articles, books, websites, unpublished Master’s theses, and low-brow pseudo-science that eked its way into the lower echelons of science journals. When such sketchy information makes up the majority of the material publicly available about loons, there is a real danger that speculation and pseudo-science might drown out real science.

There is good news, however. Our understanding of loon biology is better now than ever before. Across the continent, loon researchers have started to mark individual loons, examine many aspects of their ecology and behavior, use powerful statistical tests, and publish their findings regarding loons in peer-reviewed scientific journals. This last step is critical, because peer review means that three or more scientists are criticizing a paper submitted for publication anonymously and candidly before publication. In most cases, scientists who review loon research do not themselves study loons, so they can bring an important bit of objectivity to the process and read what a loon scientist writes without preconceived notions about the species. Reviewers who are not loon researchers, in effect, are helping pull the study of loons into the mainstream of scientific research. If scientific studies on loons are treated with the same level of rigor as those on fruit flies, downy woodpeckers, wolves, elephant seals, and angelfish, loon science will eventually become as robust and reliable as science carried out on other species.

Such rigor in loon study is long overdue. Now that we see multiple populations of loons declining in number or reproductively, we must do better. We need to advance from “there are still loons on my lake, so the population is stable” to careful, longitudinal quantification of adult survival, juvenile survival, breeding success, and other demographic parameters that can contribute to a valid statistical population model.

Why does it matter? Because when we fall into that very human trap of expounding upon a topic without a foundation of scientific fact, people sometimes listen and use our pronouncements in ways that we did not foresee. Case in point: the Minnesota loon population. Any population ecologist who looks at the data — well, lack of data, in this case — will tell you the following. We truly have no idea whether the population of loons in Minnesota is rising, falling, or remaining steady. We simply have not marked adults, carefully recorded their rate of return to their territories, measured the number of chicks they have produced, marked those chicks, measured the rate at which those chicks return, and plugged all of these data into a statistical model. Without such a thoughtful, complete analysis of survival and reproductive success, any statements about the Minnesota loon population are simply speculation — speculation that could be seized by others to undermine conservation efforts. Indeed, one difficulty faced by the “Get the Lead Out Minnesota” campaign (which anyone who loves loons and wildlife should support strongly) is that there are many baseless statements to the effect that the Minnesota loon population is stable in the media and the grey literature.

So, a plea. Let’s emulate population ecologists in describing our knowledge of loon populations in Minnesota and elsewhere. Let’s apply rigorous techniques and wait until the research has run its course to reach any conclusions. In the meantime, let’s have the courage to utter those most honest but difficult few words: “We don’t know”.

We have had an exciting last few weeks. First, our paper on population decline in northern Wisconsin has been the most frequently read paper in Condor: Ornithological Applications every single day during the past three weeks. Of course, I jinxed it, and when I looked just now I found that we have fallen and are only the second-most read paper! In any event, we seem to be getting the word out about problems that loons are facing in the Upper Midwest.

Second, Brian Hoover’s paper that describes and explains lake preferences of juvenile loons — those that have just fledged and become independent of their parents — has just come out. Brian’s paper shows that juveniles tend to visit lakes that have similar pH to their natal lakes and also that they use large lakes with a variety of fish species present. In other words, if we are to preserve the Upper Midwest loon population, we must look out not only for lakes where loons nest but also those lakes nearby where juveniles fatten themselves up to prepare for migration.

Third, our collaboration with Sarah Saunders of Audubon has borne fruit; Sarah’s paper has just been accepted by Journal of Animal Ecology and should appear as an accepted article in the next week or two. Her model, which combined measures of land use, climate, and our study population, indicates that the North Atlantic Oscillation — a fluctuating climatic pattern that is projected to increase under climate change — is having a net negative impact on both adult loon survival and chick production in northern Wisconsin. The pattern is complex, but it dovetails logically with the population trends we have seen in northern Wisconsin. The simplest interpretation of her findings is that the North Atlantic Oscillation affects food levels on the loons’ wintering grounds, which, in turn, impact survival and subsequent chick production. Sarah also found that increased human development reduced adult loon survival. Most alarmingly, Sarah’s simulations of the next decade all project decline for the northern Wisconsin population, just as our Condor paper did. So, we must look for more ways to boost loon breeding success and adult survival on the breeding grounds in an effort to counter what is a most worrisome trend.

Sarah’s findings place new urgency on my efforts to understand all 12 months that constitute a year in a loon’s life. Most recently, I have batch-plotted recoveries of loons banded in northern Wisconsin that covered distances of more than about 200 miles. As you can see from the featured image above, we have a lot of these data. (You might have to click on the title in the e-mail to see the map.) Leaving aside the small number of interesting shifts westward and northward, the photo confirms the wintering pattern that I mentioned in a recent post. Our Upper Midwest loons winter in large numbers along both coasts of Florida — especially the Gulf Coast. About a quarter of our loons, however, winter off of the Carolinas, especially North Carolina. Concerned as I am with the increased rate of mortality among adults in recent years, I cannot help thinking that hazards along these coastlines are creating trouble for them. Clearly while I can use the fall, winter, and early spring to rest and recover after intense field work during May, June, July and August, my study animals do not have that luxury.

We have had a good week on the Loon Project. A few days ago, the November 2020 issue of Condor: Ornithological Applications came out that contains our article on the declining loon population in northern Wisconsin. Our article was selected as an “Editor’s Choice” for the issue! Linda’s photo graces the cover, and it

features Linda’s “own” loons in a touching embrace. Of course, there is brutal irony here. The article documents the fact that there are fewer and fewer two-chick broods in the Northwoods these days. Linda’s picture, therefore, displays an exception to the trend of reduced breeding success in the past quarter century.

Speaking of our article, as of today it is the one most frequently read by visitors to the journal’s website. I take heart to see this; maybe that means that we are getting the word out that Wisconsin’s loon population should not be taken for granted. During my optimistic moments, I hope that attention focused on the fragility of our population and its current downward trend might help us take the first easy and obvious step to help loons. What is this step? First, we must get rid of lead sinkers and jigs, which kill many Wisconsin loons each year painfully and needlessly. This requires simply having the sense of responsibility to replace all of the sinkers and jigs in our tackle boxes with lead replacements that work just as well but do not kill loons and other wildlife. If we take this simple step and — here’s the hard part — have the chutzpah to ask our friends and relatives and neighbors to do the same, we can start a wave and get it done. Are you willing to step up and do this for Wisconsin’s loons?

A second piece of good news for the Project this week was the acceptance for publication of our collaborative paper on climatic and land-use impacts hurting the northern Wisconsin loon population. As with the just-published Condor article, this accomplishment is decidedly bittersweet. While it is nice to have your work recognized as important and worthy of publication, it is a shame to see yet more scientific evidence that spells trouble for loons.

Having just posted about our discovery that loons with chicks are in a desperate struggle to protect long-term territory ownership by hiding their own chicks and “spotlighting” neighbors’ chicks, I kept thinking: “That is pretty cool! How can I let others in science know about it?”

In looking for a suitable journal where I could submit our new paper detailing that finding, I came across the high-impact journal Frontiers in Ecology and the Environment. Our entire data paper turns out to be too long and the subject matter not appropriate for a full-length paper in Frontiers. But, while leafing through the journal, I saw that it also publishes 150- to 250-word blurbs accompanied by crisp photos that together describe an “Aha!” moment you had as an ecologist — a moment when you discovered some pattern that answered a burning question or opened up a new field of study.

That piqued my interest. Since I study the most photogenic animal on the planet and work with a talented photographer, I thought I would take a flyer, work up the nasty neighbor story, include a couple of Linda’s photos, and see what the journal said.

The writing was sheer agony. 250 words is a laughable number for explaining a tricky concept like spotlighting of neighbors’ chicks, because you have to introduce the species, explain the territorial system, describe loon chicks and their behavior, and — most challenging of all — explain the complex system of information-gathering by floaters and intrusions by territory owners that underlies the nasty neighbor story. I wore out my “delete” key writing this tiny, unbelievably dense piece.

But it was worth it. Less than 24 hours after I sent the blurb in, the editor accepted it. Linda and I are thrilled. I think my tofurkey will taste a little better this year! Sorry…..I am unable to show you the piece here because we have signed a form preventing that until publication. I promise to post a link as soon as Frontiers publishes it.

Several months have passed since our paper on the population decline in northern Wisconsin was accepted for publication. But the wheels of science turn slowly, and only just now has the online “issue” come out that contains our article. To accompany their published articles, the journal invites authors to publish also a blog post on the journal website, and I jumped at this opportunity to spread the word about the peril that my study population now faces and its particular meaning to me.

Rather than repeating that blog post here and incurring the wrath of the journal, I will include this link. The article itself is freely accessible to the public, according to the website.

What is better than finding out that your just-published article has been featured by an online science media outlet? Finding out from your dean! An hour ago this happened to me as I strolled out of our new science building.

We were excited to learn this article has excited some attention. It was a bit of a sleeper. Published in a good — but not spectacular — journal, our investigation of the flies’ impacts and loons’ logical responses to them caught the eye of the journal’s media department. I will not bore you by rehashing our findings, which I have discussed before. By the way, a related media blurb included Linda Grenzer’s cool photo of the male on her lake sticking on the nest in 2017 despite flies biting him mercilessly. (Another of Linda’s related photos appears above.)

Fortunately, this year has been a mild one for black flies. So while pondering the harsh negative impacts that black flies often have on loon nesting behavior and breeding success, we can all relish their absence.


The Nose Lake male I observed today had a conspicuous scar on his head. This particular scar, which I dutifully sketched on my datasheet, was located on the right side of his head, behind and beneath the eye. In comparison, the head of the Nose Lake female was sleek and without blemish. Scarred males paired with pristinely-plumaged females are a common sight. In fact, the scar I recorded today was the 72nd of the study – and the 63rd seen on a male. Moreover, this scar has persisted for a month; Linda photographed this bird on May 6th, and the scar was obvious then.

Scars on heads of males, which occur when they grasp each others’ heads and necks in a territorial battle, bring to mind the short, violent lives that many males lead. Slowly and surely, we are beginning to understand why male battles are fiercer than female battles. Part of the explanation for this pattern has to do with nesting behavior. We know from analysis of nesting behavior among color-marked breeding pairs that male loons control the placement of the nest. While we do not know why males control nestsite placement, we can see that male control of nest placement cranks up the stakes for male territorial battles. Why? Because male loons learn by trial and error where to place the nest. Once a male has nested successfully on a territory, he reuses that good nest location again and again, boosting his hatching success. Therefore, once established on a territory where he has nested successfully, a male has a large stake in holding that familiar territory. If evicted from there, the male must relearn where to nest and where not to nest on a new territory, which costs him precious time and energy. In contrast, females, which do not control nest placement, can freely move from one territory to another without paying a penalty in lost familiarity and, hence, breeding success. Since one territory is, in effect, as good as another to them, females should fight less hard than males to remain on a territory – and they behave as predicted.

A second part of the explanation for violent male battles is rapid senescence. Again, while we do not yet understand why males should age so badly, compared to females, the contrast in senescence has strong implications for male behavior. A male reaches a point – in his mid-teens typically —  where he is in rapid decline. That is, he is losing body condition and is at great risk for losing his territory. With the future offering little reproductive promise, many males in their mid-teens increase their aggressiveness and territory defense so that they can squeeze another year or two of breeding out of their territory. This, of course, is the terminal investment finding that I have been blogging about for the past months. (By the way, that paper has just been published online.)

With two factors – male nestsite selection and senescence – at play, we can begin to understand why males might be so violent. The factors are additive. A fifteen year-old male on a familiar territory is both falling into decline and facing a steep loss in breeding success, if evicted. So he has two good reasons to fight like hell to hang on.



Ending a short run of bad luck, we just had our paper accepted that describes impacts of black fly infestations on loon nesting behavior. As I have explained in many previous posts, Simulium annulus wreaks havoc with loons’ reproductive efforts. The biological relationship between the fly and the bird is of substantial scientific interest, and we are pleased to have finally brought our low-level data collection on this relationship to fruition.

On the other hand, our celebration of this achievement has been cut short by the cold weather still gripping northern Wisconsin. Why? Because one of our findings was that unseasonably cool springs often bring extended periods of fly abundance. So we face the prospect that the breeding season of 2018 will illustrate the threats to loon breeding we just described so vividly in our article.

There is also reason for hope. As the above figure shows, early ice-outs resulting from warm spring weather ensure that flies will be only a minor nuisance to loons. Late ice-outs pose a problem, but the results vary from a severe rate of nest abandonment (as in 2014, the worst year ever for fly-caused abandonments) to modest impacts. Let’s all hope that 2018 is one of those years when the correlation between cool spring temperatures and severe fly infestations breaks down.