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It was just a bag in the water. But it was a large white plastic bag, one flap of which protruded above the surface of Little Pine Lake in our Minnesota Study Area. As Evrett, Isaac, and I paddled across the southern end of Little Pine to begin our observations of the Dream Island loon pair, the bag caught our eye and sullied the otherwise idyllic Northwoods scene. Looking to leave the lake a bit cleaner than when we had arrived, we fished the bag out of the water.

The writing on the bag told the story.

I have a confession to make. I come from a family of non-gardeners. When we see a beautiful tree or flower, we savor it. But the notion that some act of ours might alter the health or appearance of a plant is altogether foreign. A product of suburbs of large cities, I have grown accustomed to gazing at the verdant, manicured lawns and gardens of neighbors — then turning to look ruefully at my own. Yet jealousy of my neighbors’ lawns is not enough to induce me to follow their lead.

Of course, the suburbs are one thing. Lakeshores are quite another. The bag that Evrett fished out of Little Pine suggested that a resident on Little Pine was placing fertilizer on their lawn. While the decision of how to treat one’s lakeshore is up to each individual, it has consequences for all of us. Inevitably some of the high-nitrogen and -phosphorous fertilizer that produces a lush green lawn by the lake washes into the lake when it rains. Lake phytoplankton — free-floating, microscopic algae that inhabit all lakes — are starved for nitrogen and phosphorous just like grasses and trees on land. So adding fertilizer to lakes causes higher-than-normal growth of phytoplankton, which reduces water clarity and can have a variety of more serious impacts on lake-dwelling animals and plants.

It is too early to tell whether lawn fertilizer is at the root of the water clarity loss in the Upper Midwest during the past quarter century. We do know that heavy rainfall causes low water clarity. And we know that low water clarity hinders loon parents’ feeding efforts and produces emaciated chicks. But while we investigate the specific cause of water clarity decline, wouldn’t it be prudent for lake residents to stop using fertilizer on lakeside lawns, in case loon chicks are unintended victims?

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By the way, Wisconsin Public Radio did a short segment on our study and on the decline in water clarity we have reported recently. If you wish to hear how I sound after a day of field work and a bit too much coffee, you can find it at this link.

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I went on a tour of Upper Gull Lake territories in Minnesota on May 15th. Most loon pairs there were incubating eggs.* The same was true last week when Hayden and I checked out many territories in Wisconsin. And Kaidan and I found more of the same after I returned to Minnesota a few days ago. Over a third of our breeding pairs in both states are recovering from nest failure — mostly owing to black flies. But the remainder have weathered that storm and are close to or even beyond the halfway-point of incubation.

As Sheila Johnston put it eight days ago when she and her friend Darcy led me around the Upper Gull breeding territories, we are in our annual “period of hope”. The burst of excitement and territorial intrusions of April and early May have passed. Breeders have re-paired with their old mates or replacements, established a firm grasp on their territories, and are standing vigil over their eggs.

If there is little for loons themselves to do during incubation, there is even less to do for humans who wish them well. Unless you choose to chase away eagles — Taryn Schultz on Upper Whitefish told me yesterday that a “bear horn” is her weapon of choice for this task — we can only watch with crossed fingers.

And so we wait. But our waiting is not laced with dread. It is not an “I’m afraid to look” sort of waiting. Ours is an expectant waiting — one warmed by the knowledge that we are a few weeks away from the emergence of comically small, chocolate brown puffballs that behave like awkward, bumbling adult loons but otherwise resemble them only faintly. The appearance of these puffballs brings the hopeful tedium of incubation to a most satisfying close.

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* The striking photo of the Upper Gull – Causeway nest in the Minnesota Study Area is by Sheila Farrell Johnston, who led me on the tour of the Upper Gull – Causeway on May 15th. Thanks, Sheila!

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Last year I reported precocious territorial behavior by one two-year-old in Wisconsin and another two-year-old in Minnesota. These sightings were extraordinary. Before 2023, we had no record of an adult loon younger than four years of age holding or attempting to hold a territory. Naturally we were excited to see whether those youngsters would return at age three and continue to show assertive territorial behavior well ahead of schedule.

We were not disappointed.* “Junior”, as I reported recently, is firmly ensconced on the Oneida-West territory in our Wisconsin Study Area. Meanwhile, the now three-year-old who seemed determined to settle on Pig Lake on the Whitefish Chain last July appears to have claimed the Ossawinnamakee-Boozer’s Bay territory…..and is nesting! This young Minnesota male** was hatched in 2021 by the Ossie-Muskie Bay pair. So he has settled only a few miles from the territory on which he was raised three years ago.

It is cool to see two loons in different states set the record for youngest territorial breeder simultaneously. This finding suggests that all adult-plumaged loons, even very young ones, are capable of breeding. The result also implies that many young adults would settle and breed if the habitat were not already occupied by older loons.

Could it be just a wild coincidence that two such unlikely settlements transpired at the same time? Yes, it could be. As someone whose job it is to look for patterns, though, I think I see the beginning of one here. We know from past work in Wisconsin that four, five, and six year-old adults are bigger, stronger, and more competitive for breeding territories than two and three year-olds. We know also that the pool of four to six-year olds looking for territories has become depleted by poor breeding success over the past decade. In other words, fewer chicks fledged has led to fewer young competitors scoping out territories to claim. The sudden settlement of two very young adults in Wisconsin and Minnesota suggests that territorial competition has softened to the point that two- and three-year-olds can now compete for and claim territories.

So the excitement of watching territory settlement by very young adults is tempered by the nagging concern that these events are further evidence of a downturn in the breeding population. But maybe I am overthinking it. For now, let’s savor the spectacle!***

* These cool findings are not mine. Hayden and Claudia, our scouts in Wisconsin and Minnesota, found and ID’d each of these adults on territory. Kudos to these two outstanding field workers, who have braved cold, damp conditions to ID returning breeders in both states!

** I initially called this bird a female on the basis of size. It seems I was wrong. Its settlement so near its natal territory makes the loon almost certain to be a male.

*** The featured photo above is by Claudia Kodsuntie, who scouted our study lakes in Minnesota. It pictures the hind 3/4 of the 3-year-old adult on Ossie-Boozer’s Bay. The photo is not beautiful. I like it, though. It shows the kind of quick underwater view of colored leg bands that one often gets during the early census period. So it gives you a good idea of the challenges that Claudia and Hayden have oversome to make this blog post possible.

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I left you hanging last July. A young adult male in Wisconsin seemed on the brink of achieving two spectacular firsts for our long term study. He was attempting to settle at the age of two, two years younger than any male or female loon had ever settled. And he was making a play to claim his natal lake as a breeding site, which we have never observed. In the end, his effort fell short. “Gs/C,Y/S” — whom Linda calls “Junior” because he is the son of Clune, the long-time male on her lake — could not sustain his hold on Muskellunge Lake. For a time, he fell off our radar.*

But the Loon Project scout for Wisconsin this year, Hayden**, found Junior — now all of three years old — on Oneida-West earlier this week. (Oneida Lake is just over 7 miles from Muskellunge Lake, Junior’s natal lake.) Junior has not been idle. He has paired with one of our best-known females, “Silver/Blue,Orange-dot over Orange-dot”. Let’s call her “Dot”.

Dot is the second oldest adult loon in the Wisconsin Study Area and an accomplished breeder. She was banded in 1997 on the Oneida-East territory, where she reared 22 chicks to adulthood between 1997 and 2013 with two different males. Dot was evicted from Oneida-East in 2013, but that did not stop her. She moved around a bend in the lake to the Oneida-West territory. Between 2014 and 2020, she raised 3 more chicks to fledging with two different males on Oneida-West. In 2021 she again lost her breeding position to a younger female. I thought we had seen the last of Dot. But female loons are nothing if not resilient, and Dot was not ready to quit.

We are not sure what to expect from this unlikely pairing. Three-year-old Junior would shatter all records by merely building a nest and beginning to incubate eggs. And 31-year-old Dot is astounding us simply by remaining in the game. We have never seen such an inexperienced male pair with such an accomplished female. Whatever happens from this lopsided pairing will be a surprise. I guess this is why I continue to study loons.

*The featured photo is by Linda Grenzer. It shows Junior on her lake back in June of last year.

**Hayden is doing his own impression of Junior. Although he knows Oneida County well, Hayden is new to loon field work and ID’ing loons from leg bands. Not a problem! Hayden is sweeping efficiently across the study area, identifying territorial adults like a seasoned pro. If you see him out on your lake in his canoe, give him a pat on the back for his incredible efforts this spring!

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At a March meeting of loon researchers in New Hampshire, John Cooley of the Loon Preservation Committee showed that the recent increase in severe rainstorms in the Northeast has made flooding of loon nests a routine cause of nest failure there. John’s report was eye-opening to me for two reasons. First, nest floodings occur seldom among Upper Midwest loons, so his result showed that environmental threats facing loon populations vary regionally. Second, and more important, John’s findings pushed me past a personal cognitive tipping point. I now see clearly that climate change, which has negatively impacted plants and animals worldwide, has not spared the common loon.*

I must admit that I was among those who hoped that loons might dodge climate change. I have long understood that hundreds of terrestrial birds are being adversely affected by changing patterns of temperature and rainfall. But loons are aquatic, I reasoned. Maybe they are different.

In fact, the list of climate-related factors known to harm loons is growing. In addition to the new flooding threat from storms that John’s talk revealed, the list includes black flies, which are getting worse owing to increasing annual rainfall. And our just-published paper shows yet a third problem that rainfall poses for breeding loons. In a nutshell, July rainfall reduces water clarity, which hinders loons’ efforts to capture fish to feed their chicks. This problem has led to a decline in chick mass and increase in chick mortality over the past 25 years in northern Wisconsin. If you are keeping score, we now know of two climate-related patterns that reduce hatching success of loon eggs and one that increases mortality of chicks after hatching. It is no wonder that loon reproductive success is falling across most of the breeding range, including its heart, in Canada.

These are not short-term patterns likely to reverse themselves in a year or two. Flooding, black flies, and water clarity have been getting worse for at least 25 years. No rational person who has seen these data and is capable of looking at the world with an objective eye can doubt that climate change is harming loon populations.

What now? Do we resign ourselves to loon population decline in the Upper Midwest? Do we accept the models that show the breeding range shrinking northwards until the species no longer breeds in the United States by 2050 or a bit later? Do we sit down with our children and grandchildren and explain to them that they will have to go to Canada to see the birds whose charismatic presence near our summer homes has so enriched our lives? I don’t think so. We cannot reverse climate change in a hurry. We cannot stop rain from falling. But continued field research might allow us to pinpoint climate-related hazards faced by loons — such as the precise identity of the material that rain is washing into lakes to reduce water clarity — and use that information to mitigate the harmful effects of climate change. The current picture is disheartening, but we must do what we can to save loons.

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*Featured photo by Linda Grenzer on April 8. Loons, mostly males, have begun to trickle back to the Northwoods. Linda took this photo of the male that has bred for 12 years on Deer Lake in Lincoln County. But here he is exploring nearby Muskellunge Lake, to which the longtime male resident did not return in 2023. It will be interesting to see if he settles on Deer Lake, where he has experienced seven nest failures in a row, or moves over to Muskellunge, which has a very good track record of chick production.

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Humans are social animals. Living as we do in an environment full of family ties, friendships, and competitive rivalries, we must be skilled at recognizing other members of our species as individuals and assessing the benefit or threat they pose to us. An abundance of individual cues help us identify each other, including face, body shape, posture, size, gait, voice, and mannerisms. When you consider the vast array of human attributes that betray identity, it is not surprising that we can recognize conspecifics easily — and often from a great distance.

But loons are far less social. Although loons gather in large groups seasonally, these are either: 1) loose aggregations of strangers waiting for ice out on their lakes in spring, or 2) feeding assemblages — again consisting of strangers — during the fall. During other seasons, loons are either solitary (winter) or confined to a territory with their mate and chicks (summer). Based on their limited sociality, then, we would predict that loons should recognize conspecifics rather poorly. That is, loons must be able to tell their mate apart from intruders. And breeders should also recognize neighbors, which do not threaten their territorial ownership, and the few young nonbreeders that intrude persistently into their territory and do threaten it. But loons have no friends and allies, as most humans do. So we would not expect loons to be able to recognize scores of individuals of their species.

Field observations support the idea that loons have limited ability to recognize conspecifics. When one pair member returns to its mate after a trip off territory, we can observe mate recognition in action. Loons are typically uneasy in the initial stages of such reunions. In many cases, the returning pair member lands 50 meters or more away from its mate. Both pair members immediately assume an alert posture. After several anxious minutes, the returning pair member creeps closer to its mate, and eventually both pair members relax and begin to act normally. Observations of this kind suggest that: 1) even loons’ recognition of their mates is not immediate, and 2) recognition is difficult at a distance but apparently easier at close quarters. In short, loons’ ability to recognize individuals falls far short of humans’, as we expected.

Why should we care whether loons can be told apart? There are two reasons. First, proving that loons can distinguish each other visually — and under what circumstances they can do so — would help us understand their social behavior. Although casual observations suggest that inter-individual identification is difficult, we have no scientific data on the topic. Second, if we could tell loons apart from their plumage, we could use photos alone to determine whether both, only one, or neither member of each territorial pair from the previous year had returned. In this case, a reliable record of annual photos of many breeding pairs from a specific population might permit accurate monitoring of that population without capture and marking.

We have reason for optimism regarding photographic identification of individual loons. Humans can learn to distinguish individual swans from bill markings and geese from neck patterns. While loons may not differ one from another as obviously as some swans or geese do, breeding adults seem to differ consistently in bill size and shape, the pattern of branching white lines on the neck collar (see below), and perhaps also the density of white spots on the back. So it seems conceivable that photos alone might be used to tell one loon from another.

Fortunately we do not have to rely upon fallible humans for recognition of loons. The development of image recognition technology — used for human facial recognition — allows us to delegate the hard work of distinguishing between loons to computers. In fact, a Chapman colleague in the Information Systems and Technology department has been using artificial intelligence technology to help a computer learn what individual loons look like for the past several weeks. Her initial findings, which are highlighted in the featured image above (based on photos by Linda Grenzer and myself) are promising.

Will we be able to cease banding loons altogether in coming years and rely instead upon photographers and computers to do our work? No. As our recent finding of loss of body mass by loons has shown, we will always need to capture and measure loons in order to track fully the health and sustainability of populations. But use of AI might allow us to increase the number of populations from which we can glean information about adult survival, a crucial demographic indicator. That would be a huge advance.

By the way, many folks chipped in generously to our field effort. Thanks so much to all who donated! We now have sufficient funds to support full teams of four students in Minnesota and Wisconsin both for the first time ever. So 2024 should be a banner year for data collection. Let the loon photography begin!

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We are over halfway there. Thanks to the generosity of a lot of you folks, we will be able to put a larger team of researchers in the field this year than last. At present, we can afford to hire a research staff of three interns in Minnesota and one — and a half — in Wisconsin. This is excellent news!

Our goal, however, is to place four interns in the field full time in Minnesota and at least two (we would prefer three) in Wisconsin. To reach that goal, we will have to raise an additional $16,000.

We are fortunate that a supporter has stepped up to match all donations for the 2024 field season up to $10,000! So that gives us a path to $20,000, if we can just raise $10,000 from other donors.

If you have already donated, thank you so much! Your kindness is keeping us afloat while we look to acquire long-term state and/or federal grant funding. If you have not yet donated and would like to — knowing that every dollar from you now will bring in two dollars to support this summer’s work — please consider helping out now. We would love to ride this generous matching offer to full funding for a robust 2024 field effort!

Click HERE to go to our donate page.

Just to convince you that we really are getting research done, below is a look at the abstract of a just-published paper written by Brian Hoover (a former Chapman postdoc) and me. The paper shows that males’ yodels get higher-pitched with age. This finding suggests that old males signal their age to challengers in order to communicate their aggressive tendencies. Let me know (wpiper@chapman.edu) if you would like me to send you the complete paper. It is not out yet, but the journal is allowing us to distribute the paper to our friends and contacts in order to publicize its findings.

Thanks to Linda Grenzer, a super duper photographer, for this nice picture of the male on her lake and a chick that has just left the nest.

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   ”Fossils reveal that loons have been on earth about 70 million years, making them one of the most ancient bird families.“

This sentence, from the National Park Service’s web page describing the Common Loon, is in error. Loons — even by a loose definition — have not been on Earth anywhere near 70 million years. Moreover, this faulty information from a reputable source has spawned additional spurious pronouncements scattered across websites and social media.

On its face, the Park Service’s statement seems plausible. It feels as though loons have always inhabited northern lakes. Perhaps we feel this way because of the self-assuredness with which loons slither beneath the water’s surface to initiate a fishing bout. Perhaps it is loons’ alertness to all sights and sounds in their aquatic environment or the ease and confidence with which they move about their territories and confront intruders. On the other hand, maybe loons simply look primitive — and hence, ancient — to us when we observe their ungainly movements on land. But I suspect that — more than any other aspect of their biology — the ethereal echoing of loons’ wails and tremolos across the surfaces of northern lakes hints at an ancient origin.

Humans’ view of loons as primitive creatures emblematic of northern climes dates back to native people of North America. The Ojibwe, who have looked upon loons as harbingers of death and bearers of magic, have also shared northern lakes with them for thousands of years. Thus, from a strictly human standpoint, loons are old. That is to say, loons have been integral to northern ecosystems for as long as humans can remember.

But we humans are a very recent evolutionary arrival. Whereas mammals as a whole evolved some 200,000,000 years ago, Homo sapiens, by most measures, is no more than 200,000 years old. Human residency in North America began very recently indeed — about 16,000 years ago by common reckoning.* Humans’ recent evolutionary appearance makes our historical and cultural records worthless for charting the comings and goings of most other species.

Enough about humans. What about loons? To get a sense of how old loons are, we need to look at the entire avian lineage.

It was 145 million years ago (mya) when Archaeopteryx’ feeble wingbeats were first heard faintly overhead by the theropod dinosaurs from which they evolved. Following Archaeopteryx, the first known bird, many avian lineages evolved that were dead ends (i.e. they left no living descendants). These included the ternlike Ichthyornis (95 to 85 mya) and the massive diver Hesperornis that lived 85 to 75 mya. But early members of the chicken/duck lineage roamed Earth at around this time too, as did the flightless Paleognatheae, a group that includes ostriches and kiwis.

For their part, loons are members of a rather recent avian branch, the Neoaves (“new birds”). As the name suggests, this massive group burst onto the scene after the early avian lineages — some 60 to 50 mya.

Loons fall within a group of Neoaves termed “water birds” that includes gulls, sandpipers, herons, albatrosses, cormorants, and pelicans. Loons’ closest living relatives are neither grebes nor ducks, which they seem to resemble closely, but penguins and tropicbirds, from which they diverged around 50 mya. However, the first bird species that experts agree might be called a loon (Colymboides minutus) appeared 35 mya.** (This species was less than half the size of the common loon and less well adapted to diving.) Loon species assignable to the common loon’s genus (Gavia) do not turn up in the fossil record until about 16 to 18 mya. And the common loon itself (Gavia immer) made its debut not more than about 3 million years ago.

In short, we cannot accurately describe loons as “ancient”. If you wish to point to a member of an ancient avian lineage, you will have to settle instead for a duck, a turkey, or an ostrich. True, common loons have been plying the waters of freshwater lakes — and calling hauntingly across them — for as long as humans can remember. But that says less about the duration of loons’ residency in the north country than about our own fleeting existence there.***

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References

Brodkorb, P., 1953. A review of the Pliocene loons. The Condor, 55(4), pp.211-214.

Carroll, S.B., 2016. Genetics and the making of Homo sapiens. Human Evolution Source Book, pp.646-656.

Gingerich, P.D., 1976. Evolutionary significance of the Mesozoic toothed birds. Smithsonian Contributions to Paleobiology, 27, pp.23-33.

Lovette, I.J. and Fitzpatrick, J.W. eds., 2016. Handbook of bird biology. John Wiley & Sons.

Mayr, G., 2004. A partial skeleton of a new fossil loon (Aves, Gaviiformes) from the early Oligocene of Germany with preserved stomach content. Journal of Ornithology, 145, pp.281-286.

Mayr, G. and Kitchener, A.C., 2022. Oldest fossil loon documents a pronounced ecomorphological shift in the evolution of gaviiform birds. Zoological Journal of the Linnean Society, 196(4), pp.1431-1450.

McIntyre, J.W., 1988. The common loon. Spirit of northern lakes. UNIVERSITY OF MINNESOTA PRESS, MINNEAPOLIS, MN(USA). 1988.

Prum, R.O., Berv, J.S., Dornburg, A., Field, D.J., Townsend, J.P., Lemmon, E.M. and Lemmon, A.R., 2015. A comprehensive phylogeny of birds (Aves) using targeted next-generation DNA sequencing. Nature, 526(7574), pp.569-573.

Shook, B., Nelson, K., Aguilera, K. and Braff, L., 2019. Modern Homo sapiens. Explorations. https://pressbooks-dev.oer.hawaii.edu/explorationsbioanth/chapter/unknown-14/

* Recent stone tools suggest that humans might have arrived in many parts of North American 35,000 to 40,000 years ago. Even if this is so, we are very recent arrivals on the continent.

** Mayr and Kitchener recently reported a primitive “loon” fossil from about 54 mya. But this species (Nasidytes ypresianus) was a very different beast from the loons alive today. It possessed a wide and short beak like a modern coot, had limited diving ability, and likely fed by browsing on invertebrates, not pursuing fishes. Whether and how it might have vocalized is, of course, unknown.

*** Thanks to Linda Grenzer, for this wonderful photo of the former territorial male on her lake, Clune.

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A few years ago, a non-scientist collaborator of mine suggested that I place transmitters on loons. This was a cool idea in many respects. Transmitters would permit us to monitor loons’ locations in real time and share those data with the public on a splashy website. I agreed that the technique would be thrilling and draw lots of public interest. But when the surge of adrenaline subsided, I was left with two troubling questions. First, what scientific hypothesis could we test with transmitters? Second, how would attaching transmitters to loons help us conserve loon populations in the Upper Midwest?

I am not knocking the technique. Transmitters are a potent tool used by animal ecologists to learn about patterns of migration, dispersal, and nomadism. Kevin Kenow and his collaborators employed satellite transmitters to show that typical adult loons breeding in Wisconsin and Minnesota spend the fall on Lake Michigan before heading south for winter. Kevin’s team also learned that juveniles remain on or near their natal lakes until late November, at which time they make a beeline for their winter quarters. So transmitters have helped us pinpoint times and places that are crucial to the annual survival of Upper Midwest loons. At present, though, there is no burning question concerning loons that transmitters might address.

What questions are most pressing with respect to Upper Midwest loons? With another year behind us and the 2024 field season looming, let’s take stock. How healthy is the population of loons in the Upper Midwest? And how can we best use our resources to protect them?**

Population Surveys

Two broad censuses carried out by armies of volunteers look at loon populations across large swaths of Minnesota and Wisconsin during late July. These counts are prone to fluctuations caused by changes in personnel and weather conditions during a narrow window of data collection. Still, they provide valuable large-scale “snapshots” that, in the long run, tell us how each population is faring. Furthermore, by comparing Minnesota and Wisconsin snapshots side by side, we might discern a broader regional trend.

Wisconsin’s LoonWatch survey has been carried out every five years since 1976. The survey showed robust statewide gains in loon numbers during the 1980s, 1990s, and 2000s. The most recent survey, however, revealed a decline in the Wisconsin loon population between 2015 and 2020. (The next survey will occur in July 2025.)

The Minnesota Loon Monitoring Program generates data annually and is based on six “index” areas. The enhanced geographic dimension to the MLMP survey suits Minnesota’s loon population, which is three times the size of Wisconsin’s. From 1994 to 2010, populations in two of six areas increased, two declined, and two were stable. But trends have shifted downwards in recent years. Since 2010, two areas have been stable, two have declined slightly, and two have fallen sharply. Surprisingly, the strongest, most consistent declines have occurred in the two most northerly areas (Cook/Lake and Itaska).

If we stitch Minnesota and Wisconsin surveys together, we can see that the Upper Midwest loon population as a whole increased (Wisconsin) or remained stable (Minnesota) during the 1990s and 2000s. We can also detect an apparent decline across the region that began in about 2010 in Minnesota and five years later in Wisconsin.

Poor Breeding Appears to Explain the Wisconsin Decline

Our breeding data from Wisconsin shed light on the recent population decline there. During the 1990s and 2000s, Wisconsin breeders raised healthy chicks with high survival. Brood size was split 50/50 between one- and two-chick broods. Beginning in 2010, however, chick survival and mass fell, and only 20 to 30% of broods contained two chicks. Furthermore, young adult survival plunged by 60% in Wisconsin from 2000 to 2015. Thus, poor breeding success and loss of young adults seem to be driving the population decline. There are simply not enough young loons being produced to replace adults that die.

Wait a minute. The breeding decline began around 2010, whereas the population did not begin to fall until after 2015. Are these results consistent? Indeed they are. Most loons do not settle on territories until they are five to ten years old. Therefore, several years must pass before poor breeding success is “felt” in the adult population. Hence, a statewide population decline beginning in about 2015 is what we would expect from a reproductive downturn 5-10 years earlier.

Hints of a Similar Pattern in Minnesota

We have only three years of detailed breeding data from the Minnesota Study Area. These data are too few to make robust comparisons with population trends from the MLMP. Still, we can report two preliminary patterns from the state. First, the adult return rate in Minnesota (80 to 83%) has consistently run 5% below that in Wisconsin.* Second, 31% of all fledged broods in our Minnesota Study Area from 2021 to 2023 contained two chicks. This number puts Minnesota in line with Wisconsin, where the paucity of two-chick broods reflects challenges faced by breeders since 2010. The 2022 MLMP report too cites reduced chick production in recent years as a potential cause for concern. At first glance, then, the loon population in Minnesota seems to be facing the same difficulty as its neighbor to the east.

Environmental Causes of the Decline

Thus, the loon population across the entire Upper Midwest seems to be in decline owing to reduced breeding success. This is vital information. But if our knowledge ended there, we would stand no chance of fixing the problem. To do so, we must identify the precise environmental factor or factors that impair loons’ ability to breed. In the past few years, of course, we have learned that decreased water clarity and increased black flies are two such factors in Wisconsin. That is a good start. However, it will improve our understanding — and strengthen any case we might wish to make for using local, state, and/or federal resources to mitigate the problems — if we can extend these findings from Wisconsin to Minnesota.

The Plan for 2024

2024 is going to be a pivotal year for the Loon Project. Why “pivotal”? Because we have built a conceptual and logistical platform in Wisconsin for understanding the entire Upper Midwest loon population. And we have painted a clear picture of a declining Wisconsin population and its causes. In 2024 we must pivot towards Minnesota.

Thanks to the hard work of our field crews, seed money from the National Loon Center, and the growing ranks of folks in Minnesota, Wisconsin and elsewhere who support our work logistically and financially, we have spent three productive years in Minnesota. We have identified 115 territories in Crow Wing and Cass counties that constitute our Minnesota Study Area and marked adults in about 3/4 of these territories. Our task now is to place a large enough team in the field to collect high-quality breeding data from our new Minnesota study lakes.

We will use methods in Minnesota that have proved successful in Wisconsin since 1993. In the spring we will clear cobwebs from our canoes, head to our 115 study lakes, and confirm the return or non-return of each pair member. On subsequent weekly visits single team members will locate and identify each pair member and document their nesting status or number of chicks. Most critical to our effort will be recording causes of nest failure and chick loss, because, of course, poor breeding success is the root cause of the Upper Midwest population decline.

Our growing sample of survival data from adult return rates will allow us to build a population model for the Minnesota Study Area. In addition, accumulating return records will allow us to determine whether the curiously high annual mortality of Minnesota adults that we have measured by three separate means holds up over time. If so, we will try hard to identify the source of the mortality, which would be very costly to the population.

Following the field season, we will determine whether the low breeding success in our Minnesota Study Area persisted in 2024. Then we will turn our attention to environmental factors that are causing nest failure and/or loss of chicks in Minnesota. That is, we will follow up our increased field effort with a statistical search for likely causes — especially water clarity, black fly populations, and weather patterns — that might be driving a breeding decline. It will likely take several years of intense field work to get a clear picture of such causes.

Support for Our Low Tech Approach

As you have surmised, our future promises to be unglamorous and low tech. We will not use drones, satellite transmitters, amphibious vehicles, or hovercraft to collect data. Instead, trained observers will employ the field techniques that have gotten us where we are today. We will carry our canoes to boat landings, put paddles in the water, find loons, and collect as much data as grit and elbow grease allow.

Now I am asking for your help as we do this important work to save loons in the Upper Midwest. If you believe in our work and wish for it to continue, please consider a tax-deductible donation to support us. In keeping with our theme of simplicity, we run a lean operation. None of our funding goes into the pockets of senior researchers. This year we will use our funds to support: 1) field interns who visit study lakes by canoe and collect data (about $6,000 for each of four interns covers a monthly stipend and reimbursement for gas); 2) lodging for the interns and myself (about $10,000, if recent experience is a useful guide); 3) economy airfare for me to make two trips to and from the Upper Midwest and gasoline for the motorboat we use to cover breeding pairs on the Whitefish Chain ($1800); and 4) color bands for marking loons and costs to replace broken equipment and needed supplies ($4,000). So I estimate our need to be about $40,000 for the expanded 2024 field effort in Minnesota.

By the way, we currently have enough funding in place to support a modest field effort in Wisconsin. However, increased funds directed to Wisconsin would also strengthen our effort in this most valuable long-term study population. You may earmark your donation to go towards our Wisconsin work, if you so choose.

You may use this link to go to our “Donate” page. Thanks for any support you can give us. We promise to make every penny count! 

The Future

Our future prospects seem bright. In addition to cultivating a large number of supporters across the Upper Midwest, we are forming an Upper Midwest research team. Obtaining funding is always uncertain, but our new collaborators have a good track record of acquiring major regional funding. We will apply for such funding this year and, if we are fortunate, might receive it by late 2025.

If all goes well, lake dwellers in Crow Wing and Cass counties will soon get used to the same peculiar sight to which lake residents in Oneida and Lincoln counties have become accustomed: paddlers in solo canoes, wearing bleached PFDs and binoculars, scanning the lake’s surface ceaselessly for loons.

FOOTNOTES

* This pattern is enigmatic. I can think of no reason why Minnesota loons should die at a higher rate than Wisconsin loons. One hypothesis is that the pattern is the higher density of loons in the Minnesota Study Area than the Wisconsin Study Area results in greater competition for territories in Minnesota. If so, what appears to be a low adult survival rate might instead be a higher rate of eviction. From a conservation standpoint, we must hope that eviction explains the apparent difference. If Minnesota loons truly die at a substantially higher rate than Wisconsin loons, Minnesota birds would have to offset that mortality rate with considerably higher breeding success.

** The beautiful featured photo, as usual, is by Linda Grenzer. It shows a foot waggle by two-year-old male that tried to claim her lake as its territory this past summer. We are slightly worried that this youngest-ever settler is a sign of population decline in Wisconsin, because four-, five-, and six-year-old nonbreeders would normally outcompete it for this territorial opening.