Sometimes during a night of capture, when we have finished color-banding a loon and are releasing it back into its territory with its family members, I say to the bird, half jokingly, “Welcome to the Loon Project”. But I mean it. Once we place colored leg bands on a loon, we start to feel a kinship with that loon and take an active interest in its well-being.

The bond we feel with each banded loon grows as team members report its trials and tribulations across many years of its life. “Red over blue-stripe on Lumen is soooo tame!”. “Omigosh, that female on Lumen was super aggressive when two intruders landed in her territory this morning”. “Red over blue-stripe really scared a kayaker that came too close to its chicks today”. “Red over blue-stripe fed its chicks 58 times during the hour I was observing the family; those chicks begged relentlessly.” “Red over blue-stripe just skulked around the southern end of the lake this morning while her mate foraged with a new unbanded female. She looked so bummed out.” “There is a new breeding female on Birch today; she is red over blue-stripe!”

Just as we mourn when a male or female is evicted from its territory by a young adult, we cheer when it bounces back and claims a new territory nearby with a new mate. If one of “our” loons should be injured by a lure or fishing line, we spring into action to save it.

Knowing and caring about our study animals makes it more enjoyable and rewarding to observe them. But the warmth and connection we feel towards our loons is really just a pleasant byproduct of a coldly pragmatic research philosophy: mark every loon you can, and track marked individuals obsessively throughout their lives.

Why are we so fixated on marking loons and studying marked individuals? Because marking and reobservation allows us to turn anecdote into science. If one watches five unmarked adult loons circling and diving together in early July on Brandy Lake, and two of the five birds yodel at each other, one might conclude that two members of the group must be males that became aggressive for some reason. If, on the other hand, the five loons are color-banded, we can begin to make inferences about behavior. We might observe that the group consists of two territorial pair members from Brandy and three intruders: a 3-year-old male floater reared on Johnson Lake, a 7-year-old male floater raised on Bullhead, and an 11-year-old female breeder from neighboring Arrowhead Lake. We might further note that the two yodelers are the 9-year-old territorial male and the Bullhead floater. And finally, we might observe that the 3-year-old and neighboring female fled from the group of 5 following the yodeling incident and flew off shortly afterwards, while the 7-year-old male engaged in many simultaneous dives with the male breeder and stayed 36 more minutes before departing from the lake.*

Of course, one visit to a breeding territory does not by itself lead to any useful scientific conclusions, even when loons are marked. But when this day’s observations are combined with those by scores of other field observers on hundreds of marked loons and thousands of early mornings, statistical patterns begin to emerge. Indeed, in a paper we just published, we document how floaters (nonbreeders too young to claim a territory) behave differently as they age, how territory owners tailor their aggressive behavior to floaters of different ages, and how loon parents optimize defense of chicks differently as they grow. So the accumulation of observations on marked, well-known loons made possible several steps forward in our understanding of territorial behavior.

Marked loon populations have value over and above the strides they help us make in understanding loon behavior. Since loon numbers have clearly declined in Wisconsin in recent years and apparently also among the less-well-known loons of Minnesota, our study animals in both states suddenly have special significance. In the coming years, we hope to use our study populations in Minnesota and Wisconsin to ascertain the causes of the declines and work with others who love loons to turn things around.

*Linda’s cool photo above is of Nelson Gould, a Chapman student, who worked with us for three years.

I have pointed out many times how science proceeds not in simple linear fashion but haphazardly. A finding may appear rock solid but subsequent findings modify our understanding, even forcing us to discard earlier conclusions in some cases. Viewed from space — and over large stretches of time — we might seem to advance steadily in understanding a phenomenon. From ground level, progress in comprehending a topic is herky-jerky; we make clear progress for awhile, then reach a dead end, back up, and find a new path forward.

So it has been with loon conservation. Thirty years ago, we feared that methylmercury was a major health hazard for breeding loons and their offspring. At the time, our fears seemed well grounded. Now, having spent millions of dollars measuring mercury levels in loons and looking for its impacts, we must reassess. We now see that, at worst, mercury has the potential to harm loons in the eastern 1/3 of the breeding range — and even there only in acidic lakes. Consequently, where loon populations appear to be declining, we can cross mercury off the list of threats and turn our attention to other potential causes. By the way, it was no mean feat to cross mercury off the list of dangers to loons. Thoughtful, rigorous work by dozens of biologists across North America has made this conclusion possible.

Our study of a much narrower topic — the loon yodel — also seems to be moving forward by fits and starts. (Linda’s gorgeous photo above shows a male yodelling in typical crouched position.) A really cool paper by Jay Mager — a collaborator with the Loon Project for several years — showed fifteen years ago that the frequency of the yodel was strongly dependent upon body mass. Large males, Jay found, had low-pitched yodels. This was fascinating to us, because it meant that male loons were revealing their size to territorial competitors! Now it is well and good to advertise your size if you are a big loon. In that case, the fact that you are yodeling tells opponents that you are motivated to defend your territory, and the low frequency of your yodel informs them that you can back up that determination with beef! But consider the mixed message that a small male sends by yodeling: “I am small but feisty”. Hmmmm. Not such a deterrent to a territorial challenger, it would seem. We are still coming to grips with this so-called “honest-signalling” of body size and trying to learn how small yodelers might benefit from yodeling.

Among males whose ages are known exactly (blue) and males whose ages are estimated (red), older birds have higher-pitched yodels.

But wait! Lately we have had cause to wonder whether body size really does have a strong impact on yodel pitch. Now that a good many males that we marked as chicks have settled to breed, we know the ages of many of our breeding males precisely. Brian Hoover, a postdoc here at Chapman, took these new age data — data unavailable to Jay Mager — and looked to see whether age is correlated with yodel frequency. As you can see from the figure, age is strongly correlated with yodel frequency: old males have high-pitched yodels. Reassuringly, the better our age information is, the stronger the correlation. That is, the blue points show a tighter age/frequency relationship than the red points.

Where does this leave us? I just explained that small males have high-pitched yodels. Now I am telling you that old males have high-pitched yodels. Can it be both? It is possible that both mass and age influence yodel frequency and could exert additive effects. (Imagine the extreme falsetto of a male that was both old and small!) However, Brian examined mass in his more complete analysis and found no evidence that it affects yodel frequency after all. In other words, we might have found a mass/frequency pattern back in 2006 simply because we did not have age data that would have shown us what was really an age/frequency pattern. Statisticians are quite familiar with this frustrating phenomenon; conclusions can change dramatically when a variable that was left out of a previous analysis (age, in this case) is added.

The finding that it might be age, not mass, that affects yodel pitch would be more palatable if high-pitched yodels by old males made more sense than high-pitched yodels by small males. But, intuitively, the new finding makes less sense! This is the delightful pickle we now find ourselves in. “Delightful” because the age pattern is robust and clear, as the graph shows. A “pickle” because we have no idea, at present, why or how old males have high-pitched yodels.

Well…so it goes in science!

He was the biggest, healthiest juvenile we caught in Minnesota last year. The Rush Lake-Northeast chick was so independent on July 16th, when we first attempted to catch the family, that we could not relocate him after capturing and banding his parents. We shrugged, returned the following night, and had better luck. At 2900 grams, “Copper-White”, as he became after banding, was 300 grams heavier than the second-heaviest chick we caught last summer and almost certainly a male.

Considering the risky environment inhabited by juvenile loons, it is a mistake, I have found, to become attached to them. So, with the exception of the “Miracle Chick” — a juvenile on Squash Lake in 2012 that lost his father at three weeks, watched his mother quickly re-pair with a new male, but still got enough food and attention to fledge — we have tried to avoid this practice. Still, Copper-White became lodged in my mind. I had great hopes for him. If any juvenile had a chance to fledge, migrate, and come back in a few years as an adult, it was Copper-White.

Large size and good body condition, it seems, are not enough to protect a loon in his first few months of life. Last Friday, the National Loon Center got a report of a loon hemmed in by ice on on Cross Lake. They raced out to check the bird, and Mike Pluimer snapped the photo above.

It was alarming enough to hear of a loon still on the breeding grounds in mid-December. By this time, loons from the Minnesota population should have arrived in Florida and begun adjusting to a saltwater diet. Our hearts sank a bit further to see the bird’s plight. Resting in a tiny pool of open water surrounded by encroaching ice, this juvenile was clearly in dire straits. Why had he failed to migrate south with others of his species? Something must have gone horribly wrong.

Following heroic efforts on the part of the Crosslake Fire Department, Copper-White was caught and transported to Wild and Free Rehab Center in Garrison. Terri and Richard, who live on Rush Lake and watched the chick grow from its earliest days, reported that the captured bird was strangely docile — another worrisome sign.

Arrow points out where Copper-White’s right wing was sheared off at the metacarpal bone by a boat propeller. (Photo courtesy of Wild and Free Rehab, Garrison, MN.)

It took little time for Katie, the vet at Wild and Free, to diagnose Copper-White’s problem. The end of the loon’s right wing had been sliced off some time ago by a boat propeller, rendering him incapable of flight. Unlike many hawks and owls, loons’ size and need for open water make them impossible to keep alive in captivity. The only option was to euthanize this bird.

Alas, I have no cheerful anecdote to cushion the blow. We are disheartened to lose a healthy, strapping juvenile loon to a boat strike. But boat strikes that injure loons are a fact of life in the Upper Midwest. We lost a healthy adult male even more tragically two years ago in Wisconsin. The only comfort here is that boat strikes occur infrequently enough in the Upper Midwest that they do not contribute meaningfully to loon mortality. At the moment, that is cold comfort.

Although it has been over a decade, I still remember that morning vividly. I was observing the banded male and unbanded female on Brown Lake as they foraged on the wide portion of the lake’s eastern side. As is the case with most of our study animals, the loons were quite tame. They reacted indifferently to my red canoe as I tracked their progress slowly down the lake.

The loon pair’s relaxed foraging seemed odd during what had been a most tumultuous year on Brown. Though the female had resided on the lake since April, three different males had vied for and held the position of male breeder for portions of the season. Ultimately, “Mint-burgundy over Silver, Green over Blue-stripe” (Mb/S,G/Bs for short) drove off his competitors and became the male breeder. Evicted from Two Sisters-West in 2008, Mb/S,G/Bs had drifted about for two years before finally seizing control on Brown. Sadly, his victory in late June 2011 came too late for successful nesting to occur. So on the day of my visit, August 3rd, Mb/S,G/Bs and his mate were merely killing time before molting and readying themselves for the southward migration.

As I watched the laid back pair forage, an intruder appeared overhead. The pair watched the intruder as it slowed, descended, and parted the water’s surface to land twenty meters away. The intruder — a female hatched and reared 15 km north on Moon Lake, near St. Germain, three years earlier — was clearly uneasy. She bowed her head, dipped her bill in the water repeatedly as she drew near the pair, and initiated many brief dives as she circled them. For their part, the male and female breeder seemed to be going through the motions. They circled slowly with the intruder and peered at her when she dove but seldom dove themselves. The video below from South Two Lake depicts a similar scenario.

Afterwards I reflected upon the encounter. More clearly than ever before it seemed to me that I was watching a jittery youngster confronting two old, confident territorial loons. I am not sure why it had taken me eighteen years to do so, but I felt that I suddenly understood something very fundamental about loon territorial behavior. Loon pairs watch the behavior of an approaching intruder closely, quickly size it up — estimating the level of threat it poses to their territorial ownership — and then behave accordingly. As a result of this particular lake visit to Brown, my research team began to recognize and record “initiates dive” behavior (i.e. being the first loon in a group to make a short dive) and also “declines dive” behavior (refusing to dive when another loon nearby has done so). These advances led to new data collection and new insights into age-related territorial behavior.

Intruders, we have learned recently, provide ample signals of their age, fighting ability, and level of interest in battling for territory ownership. As the above figure shows, one of the clearest hallmarks of youth among intruders is the “initiates dive“ behavior. Young, timid intruders with no intention of vying for territory ownership are nervous Nellies, like this three year-old female was, and carry out many initiates dives. At the same time, these youngsters almost never show the “simultaneous dive“ behavior (which signals a willingness to escalate conflict), nor do they yodel or show aggression of any kind. Without question, there are dozens of other small signals that territorial pairs pick up from intruders to assess their age and degree of threat they pose.

And territory owners act upon the information they glean from intruders. That is, they treat a harmless visitor within indifference; they behave aggressively toward a dangerous intruder. The keen ability of territory owners to distinguish between intruders helps us understand how they can survive hundreds of intrusions each year without becoming exhausted. They save energy where they can and only get worked up and aggressive when they must.

These conclusions might sound obvious and intuitive. They are. And yet it took some 20 years and dozens of statistical tests to recognize and analyze the age-related patterns in behavior that allowed us to infer how both intruders and pair members betray their motives and strategies during such encounters. Fortunately, our perseverance has been rewarded. A few days ago our paper on interactions between intruders and territory owners was accepted for publication in a good behavioral journal. It should appear in print early next year. Thus, we are incrementally closer to understanding the entire territorial system of common loons.

If you would like to support our work in understanding territorial behavior, measuring population parameters, and conserving loons in the upper Midwest, consider a donation to the Loon Project HERE. At the moment, we are hoping to buy two canoes and a small motorboat, which would allow us to continue our long-term Wisconsin research while adding new lake coverage in our new Minnesota study area in 2022. Thanks for any support you can give us!

I have said a number of times that we do not know how the Minnesota loon population is doing. That blanket statement is misleading. In fact, two well-organized efforts to gather data on Minnesota loons — both run by the DNR and staffed by armies of citizen scientists — have been under way for decades. These massive efforts have given us glimmers of information about the status of loons in the state that I will summarize here.

The Minnesota Loon Monitoring Program

Begun in 1994, the Minnesota Loon Monitoring Program relies upon volunteers to count loons within six regions in the state and produces a summary report every five years. A second project, the Volunteer LoonWatcher Survey, also run by the DNR, began in 1979. Since the MLMP aligns closely with one important goal of our Minnesota work — assessing the status of the Minnesota loon population — I will limit my comments to that survey.

Loon density (number of loons per 100 acres of lake), according to the Minnesota Loon Monitoring Program. (From 2020 report by Krista Larson; Minnesota DNR. Reproduced with permission.)

What Do the MLMP Data Show?

Of course, using volunteers — some without boats and binoculars — to measure loon numbers increases uncertainty in measurement. But despite inevitable fluctuations in measurements from individual regions and years, the MLMP survey seems to be an effective tool for estimating loon populations. So it is reasonable to look at MLMP data and expect to see meaningful patterns.

One of the first patterns you notice in the MLMP survey data is the noise within it. The true density of loons on lakes within each region of Minnesota should not vary much from one year to the next, because loons are long-lived and reproduce at a low rate. Yet the MLMP data show huge fluctuations in loon density from year to year, especially in Itasca, Otter Tail, and Becker Counties. That substantial scatter in the data is important, because it makes interpretation difficult.

Second, despite the noise, it is clear that the density of loons varies greatly between regions. The DNR’s analysis shows only one loon per 100 acres of lake in Kandiyohi County (southwestern part of the state) but three or more loons per 100 acres in Itasca County (northern part). The four other surveyed regions — Becker, Otter Tail, Aitken/Crow Wing, and Cook/Lake — have loon densities that fall between these two extremes. Differences in density across the state are significant, because they help us identify regions of particular importance to a species. With apologies to loon lovers in southern Minnesota, if loons are three times as dense in Itasca County as in Kandiyohi, then Itasca is a much higher conservation priority. (This sort of “triage” perspective is the bread and butter of conservation biology.)

Third, population trends — the aspects of the survey in which we are most interested — are dimly visible within the data, despite year-to-year scatter. According to the DNR analysis, two regions — Cook/Lake and Itasca — have seen small declines in loon density since 1994; one — Otter Tail — has seen a small increase; and the other three regions have experienced no significant change. These conclusions highlight one difficulty we face in assessing the MLMP results. If there are two bits of bad news and one bit of good, what do we conclude about Minnesota’s loon population as a whole?

According to the DNR summary, “MLMP results suggest that Minnesota’s loon population remains stable with an average of 2 loons per 100 acres of lake across all six Index Areas.” It would be pleasing to conclude, as this statement does, that: 1) there is one statewide population pattern and 2) that this overarching pattern could be encapsulated so simply. But the DNR’s summary seems to gloss over some worrisome trends in the data.

What Do the Data Show for the Past Ten Years?

In light of the brevity of the DNR’s summary, it seems worthwhile to take a deeper dive into the MLMP. One oddity of the 2020 DNR report is that it uses 1994 to anchor the trend line. Why 1994? Simply because this was the inaugural year of data collection. But we are most interested in the trend over the past decade, because that gives us a better sense of what is happening now. Over the past ten years, Crow Wing/Aitken and Itasca regions both appear to have suffered sharp declines in loon density; Cook/Lake has declined slightly; and Becker and Otter Tail regions have been more or less stable. Only Kandiyohi County provides good news, as it appears to have greatly increased in loon density in the past decade. But since loon density in Kandiyohi remains far below that in Crow Wing/Aitken and Itasca, the good news from Kandiyohi does not even begin to offset the disappointing findings from Crow Wing/Aitken and Itasca.

What is the Real Take-Home about Minnesota Loons?

We cannot reach any firm conclusion about the status of Minnesota loons based on the Minnesota Loon Monitoring Report. There is simply too much scatter in the data for that. However, careful inspection of recent findings reveals worrisome downward trends in two vital loon population hubs. I take these troubling signs seriously. With support from the National Loon Center in Crosslake, I am accelerating my effort (begun in 2021) to establish a large marked study population in one of these two hubs — Crow Wing County. In the next few years, we will produce estimates of adult survival, reproductive success, and other demographic parameters to construct a new population model for the region. Our fine-grained analysis will indicate whether the downward trend suggested by the MLMP data is real and sustained or whether those of us who wish to conserve loons in Minnesota can breathe a great, collective sigh of relief.

The fact that all loons look alike is so widely known in the North that it scarcely bears mentioning. But this fact has impacts on our understanding of loons that range from annoying to devastating. From the public’s point of view, the difficulty of distinguishing one adult loon from another is simply confusing. No doubt it contributes to the enduring myth that breeding loon pairs mate for life. After all, the loons that showed up on your lake this year looked and acted pretty much like those from the year before — and ten years before — right?

A minor source of confusion for the casual observer is a massive obstacle to the scientist. Our inability to tell one individual from another means that we can catch only glimmers of knowledge about territory defense and settlement, aging, survival, nesting ecology, and mate fidelity without marking loons individually. To view the situation more positively, the individual marking of loons has produced huge breakthroughs in our understanding of their behavior and ecology.

Yet even the marking of loons for study has severe limitations. Consider our situation in Minnesota. Yes, we banded dozens of loons in 2021 and they seem, if anything, a bit easier to approach and study than the 120 marked Wisconsin pairs we have been observing for almost three decades. But we are, in a sense, starting from scratch in the North Star State. Why? Because, well, loons all look alike! The breeding pair we marked on Rush-Northeast consists of a male that we can only estimate as being 5+ years old and a female that we can estimate as being 7+ years old. (Females settle about two years later than males do, on average, leading to these estimated ages of newly-banded adults.) The same estimated ages apply to the Rush-Boyd pair, the Ossie-Island pair, the Roosevelt-Southwest pair, the pair on Big Pine, and the twenty-odd other pairs we marked in July. In fact, many of these Minnesota loons are in their teens and twenties; a few are likely to be in their early thirties, like the female in Linda Grenzer’s photo, above.

Knowing loon ages is not trivial. Some of the most valuable findings we have made in recent years have emerged from our knowledge of loon ages in our Wisconsin study population. Most crucially, information about age helps us refine our population models so that they yield more precise predictions about population trends. So we would very much like to know the ages of our new Minnesota study animals.

How might we learn the ages of freshly-banded loons in Minnesota? Alas, there is no obvious aspect of loon appearance (like wrinkles or grey hair) that can clue us in. However, one exciting possibility is telomeres.

Telomeres are simple segments of DNA that sit at the ends of chromosomes. They are not genes, nor do they contain genes. Instead, telomeres serve as protective “end caps” on chromosomes. Unlike genes, which reside on chromosomes and are always replicated in their entirety when a chromosome is copied, telomeres become shorter each time a chromosome is replicated. Why? Because the process of DNA replication is imperfect and can never quite replicate the entire ends of a chromosome. Since telomeres reside at the ends of chromosomes, a portion of each telomere is shaved off each time a chromosome is replicated. In effect, by allowing themselves to be shortened, telomeres sacrifice a portion of their length to prevent genes from suffering the same fate.

If telomeres get shorter each time a cell replicates, then they might serve as a clock within the bodies of animals. Young animals should have long telomeres, while old animals — whose cells have undergone many rounds of division — should have short ones. Studies in many vertebrates have confirmed this broad expectation. In fact a recent study showed that telomere length is quite closely correlated with age in a wild bird.

A new collaborator at Chapman is currently measuring telomeres of Wisconsin loons using small blood samples we collected. He is at a very early stage, but his findings so far are promising.

Ys/Gs,S/Gs Townline, 6-year old T/S = 1.02
Bs/Ar,O/S Two Sisters-East, 9 years old T/S = 1.06
Ts/S,W/W Mildred, 21+ years old T/S = 0.71
S/O,O/R Arrowhead, 22+ years old T/S = 0.91

Thus, two young males known to be six and nine years old had rather long telomeres, while two females in their 20s had short ones. This difference occurs despite a pattern that we had noted earlier about loon telomeres — that females generally have longer ones than males.

So we await further telomere measurements from our Chapman collaborator with great anticipation. If Wisconsin data show that telomeres are predictive of age in loons, we will begin to be able to separate the old-timers from the young whippersnappers in Minnesota.

It seems ages ago when my team was out on the lakes, finding pairs with chicks, capturing and banding them — then hastily storing our canoes and the Loonmobile for the winter. So much has occurred since early August that those frantic days linger in my brain only as a hazy memory.

But the loons stayed on. While I was vacationing in the East, attending faculty retreats, and lecturing with a mask and fogged glasses so that we could keep classes in-person, loon parents continued to stuff their young with food, chicks matured and learned to fly, and most adults abandoned their territories for the Great Lakes. Even now though, as I brace myself for that peculiar mixture of joy, renewal, and mortification that only Thanksgiving with family can bring, loons remain on many small lakes in the Upper Midwest. Most are juveniles, like the one in Linda Grenzer’s photo, which often postpone migration until the very last second. This strategy probably permits them to maximize their energy reserves for their first long overland journey to Florida.

So hold a good thought for the stragglers. The Brandy Lake chick, which a lake resident told me about in an anxious e-mail today, is among them. Perhaps by the time we are all sitting down for our Thanksgiving meal, that strapping juvenile will have begun winging his way anxiously in a south-south-easterly direction. Though he cannot have a clear picture of his destination, he will cease his migration off of Cedar Key, Panama City, Tampa, Fort Myers, or Apalachicola. For a time he will be that nondescript brownish diving “duck” that some young family from Nebraska watches distractedly while building their sand castle. Let us hope that we see him back up north in a few years — and in more striking attire.

As we motored around the Whitefish Chain in late May, the thought crossed my mind. As I looked over Katy and Jordana’s field notes from Minnesota in June, it occurred to me again. And by the time we banded five tightly-packed loon pairs on Ossawinnamakee Lake in a single night in July, I had become utterly convinced: there are more loons per lake, on average, in our new Minnesota study area than in our long-time study area in northern Wisconsin.

Of course, it is one thing to have a gut feeling that a natural pattern is out there and quite another to demonstrate that the pattern is real. Indeed, having enough self-discipline to wait and test a hypothesis instead of blurting it out and selling it as fact is what separates science from…..well, something less than science.

So I examined our data from both study areas. If there are more breeding loons per acre of lake in Minnesota, the difference should be evident from a statistical analysis. I looked at all lakes between 165 and 740 acres in both study areas for which we have reliable data, divided lake area by number of breeding pairs, and ran a test. The result: In our Wisconsin study area, a loon pair’s average territory size is 282 acres, while in Minnesota an average pair occupies a territory of only 180 acres. This is a highly “significant” statistical difference, which means that the huge disparity seems to represent a real pattern, not just a chance result.

What does it mean? Having done the easy part — finding a difference — we are now faced with the thorny task of explaining it. Innumerable hypotheses leap to mind. (1) The slightly different climate of central Minnesota might support a denser breeding population than the northern Wisconsin climate. (2) Lake chemistry might be more favorable in Minnesota and thus explain the difference in density. (3) Minnesotans are somewhat more apt to put out artificial nesting platforms for loons (21 of 105 territories; 20%) than are Wisconsinites (23 of 216; 11%), which might support more loon pairs. (4) Predators might be more abundant in Wisconsin and/or food scarcer. (5) Minnesota lakes might be more convoluted in shape and thus contain more natural boundaries that allow coexistence of more loon pairs on the same area of water. (However, a quick glance at lake shapes suggests the opposite — that our Minnesota lakes are more round.) (6) Human harassment of loons might be more intense in Wisconsin. (I have not noticed any such pattern, however.) In short, we have lots of questions and no answers, at present!

Now, it is important to take a step back. We have under active investigation only about 10% of all Wisconsin loons. In this beginning phase of Minnesota research, we have only 1.4% of all Minnesota loons in our study. (The nice loon photo by Katy Dahl above shows only one of about 14,000 loons in the North Star State.) So our two study areas — especially the one in Minnesota — capture only a snapshot of a small subsample of each population. The overall statewide loon densities might be quite different. Still, the two study populations are similar in numerous ways, including latitude, degree of human lake usage, and deep affection of almost all lake residents for the species. The ability of Minnesota loons to live “shoulder-to-shoulder” tells us something profound, I think, if we can only ferret it out.

Although most of our research team is long gone by September, Linda and Kevin Grenzer remain in Wisconsin. At a time of life when most folks widen the dimples in their BarcaLoungers, these two are devoting their time to rescuing injured birds. (Linda, of course, is also one of our field team members and a gifted photographer to boot!)

Linda and Kevin have gotten more proficient at rescue in recent years. Four years ago, they often found themselves hours from home on some false alarm — an eagle that was heat-stressed but recovered; a loon that seemed wounded but was merely preening. These days they insist on seeing photos or getting vivid descriptions of injured birds from experienced observers before setting out to save them.

After Ken and Joanne Lubich sent us the photo at the top of the page, it was clear that a bird was in trouble. The Lubiches keep a close eye on the two loon pairs on eyeglass-shaped Two Sisters Lake. On a routine patrol around the lake on September 13th, they were horrified to see that one of the two strapping chicks on the east lake had a huge muskie lure attached to its left leg and was swimming erratically.

It might seem difficult to find the positive here, but, in fact, this chick was fortunate. The Lubiches keep a close eye on the loons on Two Sisters and have a network of contacts who live on the lake. Thus, the distressed chick was found only a day or so after being hooked. Furthermore, Joanne and Ken know Linda and Kevin and immediately reported the hooked bird to folks who could help it.

Once they made it to Two Sisters yesterday, Linda and Kevin were able to capture the distressed chick, when it ventured close to shore. A quick inspection told them that at least two of the hooks on the lure had punctured the chick’s foot tissue and become infected. They decided to transport the bird to REGI for treatment.

As is evident from the photo below, we had captured and banded this chick. On the night of capture, July 13th, the bird weighed 2460 grams. Yesterday, the chick weighed 2470 grams, which means that it was only 10 grams heavier yesterday than it had been two months before. This tells us that the bird has lost a great deal of weight — perhaps 500 to 600 g — owing to the hooking. Needless to say, loons go downhill quickly when they are prevented from feeding themselves. This bird probably fed little or not at all for six days.

The world is looking brighter for this chick. Multiple hooks were removed from its foot. One hook was too close to a bone to remove and had to be left in the bird. (REGI staff hope that swelling in the foot will push the hook out in time.) If its injured left leg recovers, and it becomes fully mobile again, the bird will be released in a few days back on Two Sisters. Meanwhile, this loon is taking full advantage of the favorable fishing conditions provided in its temporary home!