The beginning of the tale is heart-rending. A gosling is orphaned before hatching. A loon pair fails to hatch chicks of their own and, seeking to fill the void, sits on eggs they find near their nest. When these two desperate parties converge into a single — if nontraditional — family, they produce a heart-warming story*.

To see two species coexist despite 90 million years of evolutionary time spent apart is surprising. To see them not merely tolerate each other but become thoroughly interdependent, as parent and offspring, is truly striking. Such an improbable scenario makes one hopeful. This story suggests that differences between groups — even vast ones such as between geese and loons — can be overcome.

On the other hand, the sight of a gosling nestled comfortably on a loon’s back is also strange. It is a reminder — like exploding black fly populations, loss of water clarity, devastating storms, and the sudden abundance of wake boats — that the loon’s world has changed.

*Thanks to photographer Brad Thompson, who shared his beautiful photo.


What if we had an early warning system in loons that could alert us to population decline, like the proverbial canary in a coalmine?

Male loons might serve as such an early warning system. That is, careful monitoring of the health of male loons might provide a good indication of the health of the loon population as a whole. How is this possible? Because the more we study the breeding ecology of loons, the more stark differences we find between the sexes. And — more to the point — male loons have some chinks in their armor that females do not.

Most fundamentally, males are 25% larger than females. Greater size places greater energetic demands on males. Males are living “closer to the edge” than females and might often fail to acquire enough food during the season to maintain good body condition. Thus, a decrease in the quality or quantity of food — which could set in motion a population decline — should strike males first and hardest. Indeed, as the graph below shows, the average mass of male loons has declined in northern Wisconsin over the past 30 years in a way that suggests they are having more time finding food now than they used to. (Note that females have not declined in mass during the same period.) The obvious conclusion: something in Wisconsin lakes has changed in the past three decades that has impaired males’ ability to feed themselves.

Average masses of male and female loons in northern Wisconsin, 1991 to 2021. Male mass has declined significantly during this period, while female mass is unchanged.

Long before I discovered that male masses were in decline, I had begun to worry about male loons. You see, male loons live shorter lives than females. This means that there are simply fewer adult males around. In fact, the majority of non-territorial adults (“floaters”) in the loon population are females. Since males are in short supply, the loss of an adult male breeder on a lake or territory sometimes leads to that territory becoming vacant. In fact, in 23 of 24 well-documented instances where an adult breeder’s death was associated with a territory vacancy, the dead breeder was a male. Vacant territories are, of course, a harbinger of overall population decline.

Sadly, recreational fishing does not help the situation. Possibly because males’ greater size makes them a bit more desperate to feed themselves, male loons are twice as likely as females to be hooked by anglers or become entangled in fishing line. This pattern is well-documented in New England loons, but the same scenario plays out in the Upper Midwest. Specifically, of 47 known fishing entanglements among our study animals, 33 involved males, and only 14 involved females. Angling mortality, then, exacerbates what is already a female-skewed sex ratio owing to early male senescence.

It is difficult to predict the future, but I think you can see why I am concerned. Male loons appear to be in trouble. We cannot say for certain whether mass loss by male loons will cease or continue. Furthermore, we have no evidence to date that the 4% net loss in mass by males since 1991 has negatively affected their survival. So it is too early to panic about these patterns. But it is also hard not to feel like a miner glancing anxiously at his lethargic canary.

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 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!

In a recent post, I described how the popularity of loons and the willingness of many folks to pontificate about them without solid data or thoughtful scientific analysis makes loons unique. I tried to point out that this practice can be harmful, if we make misleading statements about loon conservation at a time when some loon populations are declining.

Now, let me give an example. Millions of state and federal dollars have been spent in recent decades in attempting to measure the effect of methylmercury (the toxic form of mercury) on wild animals, especially birds. Without a doubt, more funds have been spent analyzing mercury impacts on loons than on any other aspect of loon biology. What have we learned from this body of work? The major take-homes are that: 1) mercury certainly can affect behavior and survival of adult loons and chicks if it occurs in a high enough concentration in their tissues, 2) high mercury levels tend to occur mainly in loons living on small, acidic lakes, which have negative effects on loons that have nothing to do with mercury, and 3) harmful concentrations of mercury do not occur in most geographic areas within the breeding range. In short, despite an abundance of research and the expenditure of millions of research dollars across three decades, we have no direct evidence that mercury negatively impacts loon populations. In fact, the consensus among loon scientists is that mercury probably has little or no negative impact on most populations.

The situation is dramatically different with lead. Careful analysis of loon carcasses in New England has shown us that lead is quite deadly and affects a great many loons. (The featured photo above shows a deadly lead sinker in the stomach of a loon that died a few days ago in Wisconsin. Photo by Wild Instincts.) In a 2017 study, Grade et al. determined that a whopping 48.6% of the loons they examined had been killed by lead sinkers and lures. The authors estimated that this mortality rate had reduced the New Hampshire loon population by 43%.

The contrast between mercury and lead is stark. Mercury might affect loon survival and breeding success slightly in a few isolated populations. Lead has been shown to cause half of all loon deaths in one state and to make an enormous dent in the loon population of that state.

The contrast between these two toxins goes further. Mercury exposure is pushed to high levels mainly through burning of fossil fuels like coal and oil, which contain mercury. So reducing loons’ exposure to mercury requires a long-term effort to reduce burning of fossil fuels over a large geographic area. In contrast, loons are exposed to lead through our use of lead sinkers and fishing lures. The remedy for lead-related loon deaths is simply to implement use of lead-free fishing tackle in lakes where loons breed. (Steel, tin, and tungsten are common alternatives). Indeed, lead bans are now in place across New England.

Here is the problem. Despite the lack of evidence that mercury affects loons in nature, mercury has become the “go-to” environmental toxin mentioned by many loon researchers. Mercury has become such a prevalent scapegoat in grants, reports, and even published papers that many of us are not keeping its limited impact on loons in proper perspective. A clear-headed, candid, objective review by a loon researcher with a strong background in mercury toxicity would do wonders for loon conservation. At a time when studies have just reported long-term declines in two loon populations, those of us trying to conserve loons would do well to focus our attention on the real enemy.

We have been out all night for the past week capturing and marking adult loons and chicks. It is tiring work. Last night, for example, we had to carry our 14 foot motorboat off of a highway shoulder and into Sunday Lake. Next, we hefted it down a long flight of steep stairs, out a long narrow dock and into a marsh to reach the Minocqua-Huber Bay territory. My back still aches! But these visits were productive. In both cases, we captured a male hatched in the study area, his unmarked mate, and their two chicks. So our strenuous efforts were rewarded. (The Sunday male is a fifteen-year-old who was hatched on Seventeen Lake; the Minocqua male is only six and was reared on Brandy Lake.)

Our third lake of the night has a public landing. It was a breeze to back the trailer up and slide the boat into the weedy, pike-rich waters of Little Bearskin Lake. For a change, we were not sweating profusely and breathing hard as we began our improbable search for the pair and their young. However, we were not prepared for what we discovered.

The visit began routinely. We motored slowly to the middle of the lake to listen for the birds, as we often do. Within a minute, a bird wailed in the southeast corner. We were thrilled, because we seemed to have found the family quickly. The loon that had called was, in fact, only the female from the pair, who had wandered off separately from the male and chicks. Nevertheless, she responded strongly to our chick calls and was easy to scoop out of the water. As we removed her from the capture net, we were alarmed to find that she had a fishing lure and monofilament line wrapped tightly around her left leg.

Fishing line is unkind to wildlife. The very properties that make it attractive to anglers — its strength and thinness — give fishing line the ability to cut deeply and mercilessly into the flesh of animals unfortunate enough to become entangled in it. As the photo above shows, the female’s left leg was tightly wrapped, and a lure and hook had become attached to her leg.

Linda was able to cut away the line that had pierced the scaly, keratinized outer layer of the female’s left leg (see video below) and remove the attached lure. We are concerned about the raw tissue that was exposed by this piercing, but Linda applied antibacterial ointment, and we are hopeful that she will recover.

An injury to any loon is painful, but this one was doubly so. This mother of two chicks is the second oldest loon in our study area. She is at least 31 years old! First marked in 1996 on West Horsehead, she raised 19 chicks with three different males on that lake but was evicted in 2018 and fell off of our radar. We were delighted to see that she had resettled on the very productive Little Bearskin territory this spring with the 18 year-old male there. The two healthy chicks she has raised with him provide further evidence that females retain the ability to produce young during their later years.

But we worry. At 3500 grams, she is 250 grams or so lighter than when we captured her several years ago. This, the fact that she had left the male to care for the chicks last night, and the odd not-quite-wails that she uttered after we released her might indicate that she has been compromised by this angling injury.

In fact, she and we were extraordinarily lucky. Most “off-chick” adults — those not tending their chicks — are difficult to find at night and capture. Only the fact that we stumbled into her before we found the male and chicks allowed us to catch her, free her from the tightly-wrapped fishing line, and treat her injured leg. Now, at least, she has a fighting chance to resume her parental responsibilities, regain lost weight, return to her Florida winter quarters — and perhaps return again in 2022.

Three days ago, Allison and I had only one car, so we covered a double circuit of lakes. We loaded two solo canoes precariously on top of our ’07 Toyota Corolla — “That seems safe”, I said, tugging on one of the straps we had used to lash the boats to the roof rack and smiling reassuringly at my dubious daughter — and headed to a northern tier of lakes. I dropped her and her canoe at Brandy, and scurried across Highway 51 to Arrowhead. An hour and half later I covered Kawaguesaga-North, while she observed at Bullhead, and so forth throughout the day. It was tiring, and Allison inevitably had to wait ten minutes or so for me to drive back from my lake to hers, but we visited four sets of lakes this way. Covering many lakes with limited personnel is central to the ethos of the Loon Project, and I was delighted to walk the walk on Sunday.

While our highly fuel-efficient observations on our last day in the field were very cool, the portrait of reproductive success that emerged from the lakes I visited was decidedly ambiguous. The Hodstradt pair has two thriving, five-week-old chicks. During my visit, the ten-year-old female (hatched on Butternut Lake in Forest County) was struggling to provide enough food for her large family. The alpha chick begged her mercilessly and received 14 feedings. In contrast, the beta chick, which only got two food items, was on the receiving end of three harsh pecks from his larger sibling. Still, Hodstradt has a history of producing two-chick broods, so they appear to stand a good chance of fledging both young.

In contrast to the thriving family at Hodstradt, the Arrowhead breeding pair has been impacted heavily by a wing injury to the male. Even as I began to pull the canoe off of the Loonmobile, I saw a large loon preening awkwardly forty meters off the Arrowhead boat landing. “Uh-oh”, I thought. The telltale drooping of his right wing revealed the male’s identity long before I observed his plastic leg bands. He was alert and responsive to his environment, but he looked worse than ten days before, when we had captured him at night and inspected his injured right wing. I sighed and shook my head; we had hoped he would recover and rejoin his mate and chicks. As I took note of his struggle to preen without stretching his damaged wing, his sodden plumage (which occurs when loons fail to cover themselves with protective oil from a special gland near their tail), and his willingness to permit a fisherman to drift to within ten meters, a grim realization hit me. This male is going downhill rapidly and is not going to recover. (Marge Gibson, a veterinarian with REGI, has inspected a series of photos taken by Linda, and is confident that the right wing is broken — probably at the humerus — an injury she has seen often after severe blunt-force trauma such as a strike by a motorboat or jetski.) Despite the male’s injury, I wondered why he was confining himself to the small, protected cove off of the boat ramp, instead of remaining in the main body of the lake.

I quickly learned why the wounded male was hiding. A pair of loons rested confidently on the southwestern end of the main bay. Unlike the injured bird, these two sat up high on the lake surface. A short time later, they foraged in plain view in the middle of the lake. In other words, they acted like they owned the place. Clearly the male had taken refuge in a protected cove in order to hide from these two new adults that, in the absence of territory defense, had laid claim to the lake. Indeed, the new pair swam east to the mouth of the male’s cove as I observed them, as if hunting an intruder they wished to drive from the lake. I was relieved that neither pair member gave any sign that they detected the injured male in the cove. Somehow — either by diving often, hiding under a dock, or perhaps pulling himself up onto the shore — he eluded them and spared himself their attacks.

The wounded male was not the only loon systematically avoiding the new breeding pair at Arrowhead. As I patrolled the shoreline of the lake, I found his mate foraging madly for one of their two chicks in the northeastern section. Though her territory has slipped away because of her mate’s and her own inability to defend it, the female has been unwilling to desert her seven-week-old chicks. In order to avoid the watchful eyes of the new pair, she and the banded chick I found her with always remained within ten meters of shore and foraged among a stretch of long docks that jut out from the northeastern shoreline. As my video above shows, the chick begged his mother relentlessly for food, while she captured what few small fishes and insect larvae she could find along this sandy stretch. This brief set of observations provided a window onto the female’s plight. In order to fledge her two chicks, she must provision them surreptitiously for at least another month, wait for them to learn to fly, and then hope that they can move to nearby undefended lakes (which chicks naturally do at this age), where they can complete the growth process. The series of practice runs, aborted takeoffs, and awkward landings necessary for a chick to become adept at flight are sure to draw the attention of and aggression from the new breeding pair. If, by some quirk or miracle, the female manages to keep the chicks safe and healthy until they can fly, she will be the first adult we have ever seen to lose her mate when the chicks were younger than five weeks, have a new breeding pair take possession of the territory, yet still manage to fledge them. As much as I respect her determination, I do not like her odds.

After my report of continued decline of the former breeding male from three days ago, Linda and Kevin Grenzer visited Arrowhead yesterday. They found the same cast of characters that I had seen two days before — the skulking, incapacitated male, the confident new pair, the plucky old female, and the banded chick that she had been feeding — but, incredibly, Linda also turned up the unbanded chick that we had not seen on two previous visits and had given up for dead. In fact, Linda got a series of photos of this chick as it followed its wounded father onto shore (see featured photo at top). It is touching to observe the chick’s dilemma — sitting awkwardly and reluctantly on land, yet refusing to abandon its fading father. I guess if we are looking for a positive from the recent events at Arrowhead, it is that the family is doggedly sticking together in the wake of a gut-wrenching calamity.

The prospect that someone would feed a loon seems outrageous on three counts. First, how could a person get close enough to a loon to offer it food? Second, how many of us have small live fish in our pockets to offer? Third, we are talking about a loon, for Pete’s sake! Who would treat such a magnificent bird like a pond duck?

On second thought, I get it. People love loons. They wish to see them up close and to help them in any way they can. On its face, feeding a loon seems like a positive act. By offering fish to a loon, folks must think that they are doing their part to conserve this iconic species. At least, that is my most charitable take on the feeding of loons.

As it turns out, many loons readily accept food from humans. In fact, some loons abruptly change from being fiercely independent animals that are contemptuous of humans to shockingly needy creatures that have dropped all pretense of wildness and live only for their next handout. Linda’s photo shows a typical scenario. Here, the female waits expectantly near a human on shore. Though this human clearly has no intention of offering food, the female is so thoroughly trained to take food from humans that she does not distinguish between humans with food and those without.

Linda’s photo also highlights the particular danger that feedings can pose if they involve loon parents. If a chick’s parent is taking food from humans, the chick itself will observe this behavior and is likely to imitate it. At a time in its life when a young loon must become an efficient forager, build its flight muscles, and survive its southward migration in November, a dependency on humans is most unhelpful.

It is easy to tell if a loon is being fed by people. The video below shows such a loon. As soon as I came within view, this bird made a beeline for my canoe, and it stayed with me for several minutes. Each time I happened to move my arms rapidly, it became alert, expecting that I was about to toss a fish for it to catch.

What’s the harm, you might ask? People who feed fish to loons are providing more food to them and are possibly helping them to survive. As a scientist, I must admit that measuring any impact of human feeding of loons is difficult, and we must accept that human-provided food could help loons in the short term. But consider this: a fed loon is a loon that routinely approaches humans closely. While most of us love loons and would not dream of hurting them, not all humans feel this way. A small number of people might harm a loon that approaches closely enough to accept a fish from them. More important, loons that stay close to humans and expect them to throw food are more likely than other loons to chase fishing lures or live bait and get hooked.

So…..please, folks, if you see someone offering food to a loon, have the strength to approach them and explain why we must avoid this harmful practice. If necessary, get your lake association involved or report them to the local wildlife agency. If all else fails, I am happy to do what I can to contact the offending party and ask them to stop. I find that most people who feed loons are only trying to help them and have simply not stopped to consider the long-term harm they are causing.

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He doesn’t look it, but this male from Townline Lake, just outside of Rhinelander, is at least twenty-seven years old. He is among a dwindling few males from among those we banded in the mid 90s. This bird was banded in 1994, at which point he was certainly at least five years old, which means that he was hatched in 1989 or before. Thus, twenty-seven is a minimum estimate for his age.

The age of “Silver over Red, Orange over Green” (as I call him affectionately) is not his only remarkable attribute. What sets this individual apart from most others is his ability to hold onto his territory year after year while fledging healthy chicks. (Below, he relaxes near his mate and two strapping chicks from 2016.) A successful common loon is not only good at locating safe nest sites and defending and feeding young. A breeder that wishes to

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reproduce successfully must confront intruders that land in the territory without warning throughout the breeding period.

Intrusions are especially frequent during the chick-rearing period. A common scenario plays out as follows. Early in the morning, a male is diving for food, while his two chicks track his progress from the surface. Each time he surfaces, the chicks rush over to him, snatch food from his grasp, and nibble relentlessly at his bill, neck and chest, signaling their unquenchable appetites. On one occasion, he surfaces holding a small yellow perch, only to find five adult loons in flight above his lake. He drops the fish, gives a short barking call, and the chicks dive and head to the nearest shore. The male too dives but surfaces near the middle of the lake, drawing the now-descending intruders to himself. Three quarters of an hour later he has driven off the intruders, thanks in part to a lunge and point yodel that caused his five visitors to scatter and tremolo. Shortly afterwards his mate returns, and both parents forage for the chicks. The family suffers no further disruptions until the evening, when another group of three nonbreeders circle and land, causing yet another brief skirmish.

Considering that a large pool of territorial intruders are constantly sizing up the resident male or female of any successful territory for an eviction attempt, it seems remarkable that residents are able to hold on to their territories for even a single year. Yet Silver over Red, Orange over Green has put together a string of 23 years of straight ownership, the only blemishes a half-year in 1996 and another in 2003, when he was briefly deposed. He has fledged 20 chicks during his breeding career with four different mates. This male is not the only resident with an impressive resume. A female on nearby Langley has fledged 17 chicks on that territory since 1995, while the O’Day female has been on territory since at least 1997 and has produced at least 16 full-grown chicks during her breeding career.

But female loons are survivors. Females enjoy a high rate of survival and no detectable senescence well into their twenties. Males, on the other hand, hit the wall abruptly at age 20; almost half of all territorial males of age 20 will perish before the subsequent year. So when we see a male who defies the odds, like this one, it is worth looking closely to see if he possesses an attribute that sets him apart. As a scientist, I am loathe to draw conclusions based on a sample of one. Colleagues in my field would dismiss any such conclusions out of hand. But today Nelson, one of my Chapman research students this year, reported that Silver over Red, Orange over Green is the tamest bird we have ever measured in the study area. So let me invite ridicule by advancing a very preliminary hypothesis. Perhaps the key to lifetime productivity in a habitat rife with human recreation is picking one’s battles carefully. Maybe by ignoring the inquisitive, well-meaning primates in their watercraft, this male has been able to conserve his metabolic resources for provisioning young and driving off pesky intruders.