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.

It is a bit unseemly, I suppose, to pile on Russia now. Having been caught meddling with our election and cheating during past Olympics, their reputation could hardly get worse. Yet the metaphor of the Russian judge — meaning a person who brings a strong bias to a process that is supposed to be marked by disinterested fairness and good judgment – is almost irresistible to me at this juncture. Indeed, the metaphor has been throbbing in my brain these past weeks as I have marveled at the scores awarded to figure skaters and Big Air snowboarders.

Let me explain. I recently completed a revision of our paper on terminal investment by male loons: the most remarkable finding we have made in 25 years of research. (This is the paper showing that males become highly aggressive and territorial at the same time that their health, survival, and territory defense is declining.) Praised by three reviewers at a prestigious journal, our paper was blocked from acceptance by a fourth reviewer who insisted that we complete a complex statistical analysis to check our results. Review of scientific articles is almost always anonymous, as in this case, so we cannot know the reviewer’s identity or the reason for his/her objection. But my study of his/her statistical point convinced me that it was mistaken. Yet, the editor disregarded my carefully-crafted refutation and chose to support the reviewer. Of course, it is immensely frustrating for an author when an editor sides with a stubborn reviewer. This outcome forced us into a difficult decision: 1) kowtow to the reviewer by reworking our statistical analysis needlessly, which would have entailed a lengthy delay in publication and cost us perhaps $2000 to hire a statistical consultant, or 2) pull the plug on the submission that seemed on the brink of acceptance, pending completion of that difficult statistical revision. I hope I made the right call by withdrawing the paper and sending it to a new journal.

Two factors played a role in my decision to withdraw the paper that, perhaps, should not have. First, I have spent many months polishing this paper and am reaching the end of my rope with it. I am certain that it is sound statistically and likely to be impactful in my field, if I can just navigate the stormy seas of reviewer opinion. Second, I must soon turn my attention to acquiring new research funding and must have this paper in print in order to demonstrate to funding agencies that the past funds they have sent to me have been well spent. Thus, I have chosen to send the paper to a solid – but not highly prestigious – journal in my field, hoping to find a fast track to publication.

I am not the first person to make a decision to publish a great paper in a low-impact journal in order to keep the wheels of research turning. Each paper, in my experience, follows its own journey. A pedestrian paper sometimes catches a wave and ends up in a lofty journal, only to be scoffed at and forgotten in short order. And cool papers sometimes fall into low‑impact journals, are discovered by many scientists, and become classics. Let’s hope the terminal investment paper falls into the latter category.

I have just completed my paper on black flies. The paper presents evidence that black flies cause nest abandonment, which was lacking in the literature before. The evidence is pretty convincing, I believe. (We shall see what my scientific colleagues think when I submit the work for publication in the next week.)

In the course of looking at black fly impacts on nesting, I stumbled into two  interesting findings. These findings were serendipitous, like much of what scientists report. That is, I was keenly focused on one topic — black flies and nest abandonment — when I made a finding related to another topic — other causes of abandonment. In fact, I analyzed statistically a whole set of factors, some seemingly unrelated to black flies, that might have predicted nest abandonment. Among these were age of the male, age of the female, duration of the pair bond between them, exposure to wind (which might have kept the flies at bay), size of breeding lake, and distance from the nest to the nearest flowing water (from which black flies emerge as adults).

I was excited, but also baffled, to discover two new predictors of nest abandonment. First, pairs on large lakes are less prone to nest abandonment than pairs on small lakes. Second, pairs containing an old female are far more likely to abandon a nest owing to black flies than are pairs containing young females.

Now, I like to think that I know everything about loons. When I am visiting a study lake and someone asks an easy one like, “Do loons mate for life?”, I puff myself up, lower my voice an octave, affect a mild British accent, and pontificate on the serially monogamous breeding system of Gavia immer. But I was wholly wrong-footed by these two new findings. I had been so laser-focused on black flies as the prime movers in nest abandonment that I had included age and lake size in the analysis almost as an afterthought. I had not even considered what it would mean to learn that age and lake size were significant predictors.

The statistical significance of lake size as a predictor of abandonment forced me to confront a complex variable. If numbers of black flies are correlated with nest abandonment (as they are), then it requires no great conceptual leap to infer that black fly harassment is causing loons to abandon their nests. But the fact that lake size predicts abandonment opens up a much broader range of explanations, because lake size is correlated with degree of human recreation, pH, wind exposure, wave action, available food, and numerous other factors. Having picked through the possibilities, an energetic explanation seems most likely to explain the lake size pattern. That is, large lakes provide more food than small lakes, so loon pairs on large lakes should be in better health and condition than those on small lakes. Well-fed, healthy adults with strong immune systems should be better able to cope with the blood loss and exposure to blood-borne pathogens (like Leucocytozoon protozoans, which cause a malaria-like disease in birds) than under-nourished individuals with weaker immune systems.

What about the higher abandonment rate of pairs that contain an old female? Here again, energetics might be the key. Old females senesce — they experience much lower survival and slightly higher vulnerability to eviction than young females. So it stands to reason that old females are in poorer body condition and are more likely to abandon nests when attacked viciously by black flies. Reproductive decline among old females is widespread in animals, and the tendency of old female loons to abandon nests more readily seems consistent with that pattern.

But what about males? As I have emphasized in recent blog posts, males senesce even more dramatically than females do. How is it possible that old males can continue to incubate eggs when being bitten mercilessly by black flies when old females cannot? Terminal investment appears to be the answer. Terminal investment — efforts to increase breeding output as death approaches — occurs only among male loons, even though both sexes senesce. As the months have passed, we have learned that male loons not only become hyper-aggressive when they reach old age (15 years) in an apparent attempt to hold their territory for another year or two of breeding, they also seem to show a more subtle willingness to try harder to hatch eggs and rear young to fledging. The new finding showing that old males do not abandon nests as readily as old females when beset by black flies is thus part of a growing pattern.

My tentative explanations for the impacts of lake size and sex on nest abandonment are not the end of the story, of course. Rather, they raise more vexing questions. Why on earth would a loon settle to breed on a small lake, when small lakes doom loons to poorer body condition, a higher rate of abandonment, and the likelihood of losing one or both chicks in the event they can hatch the eggs? And even if the higher rate abandonment of nests by old females fits a growing pattern, why do males and females differ so much in their life-history strategy? We do not know….and this is why I love my work!