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I have started to call it “the Great Void”. It is the period between a chick’s first autumn and the point — at 2 to 4 years of age — when it has matured, molted into adult plumage, and returned to the breeding ground to look for a territory. Why “void”? Because we know almost nothing about loons during this period.

The Great Void used to be a nuisance. It was frustrating to think that our birds were passing through so many critical life stages without us knowing where they were or whether they were alive. But we have now pinpointed high mortality of young adult loons as the greatest threat to the loon population of Wisconsin and, more recently, Minnesota as well. “Nuisance” no longer captures the depth of our frustration. We now have to admit that we know least about our loons during the time when it matters most. So I think we need to begin to describe the Great Void as a grave concern.

Yet we are not completely in the dark. We get a glimpse into the Great Void now and then. Here is the story of one glimpse we got in March of 2024 from the wintering grounds.

As soon as he spotted it, Jim “Crater” Anderson could see the bird was in trouble. Seabirds in Panama City, Florida do not lounge on the beach in late afternoon sun like tourists from Ohio. And this one was looking especially out of sorts. It was well above the high tide point, sitting in dry sand. Crater did not think twice about interrupting his daily 10,000 steps to come to its aid.

“That is not how a duck should sit”, Crater thought, looking at the bird. Indeed, with legs splayed right and left of its body and belly in the sand, it was a curious sight. The animal skootched awkwardly across the beach and flapped frantically as he approached to within five yards, making him wonder if its legs were broken. At that moment, he felt strongly that he must capture the bird and take it to someone who could help. He removed his grey hoodie and, crouching low to the ground to appear less threatening, crept still closer. “It’s okay, I am going to get you to someone who can fix you up”, he murmurred reassuringly.

The bird was not mollified by Crater’s soothing words. Now that he was within six feet, it whipped its head around and eyed him suspiciously. He steeled himself and grabbed it, enduring its painful nipping at his arms and hands. As quickly as he could, he swaddled the bird in his hoodie to calm it and walked briskly to Rick and Sheila Harper’s house. “They have parrots”, he reasoned. “They’ll know what to do.”

The bird he was carrying was bigger and heavier than he had thought it would be – much larger than any duck he had handled. Its bill was thick and dagger-like. Its legs were not broken, just connected at the very end of its body. And – this was the biggest surprise of all — someone had placed four brightly‑colored bands on the bird’s legs. “What is that all about?” he thought.

When he arrived at Rick and Sheila’s, Kim Youngbeck was also there. The four friends placed the bird in a cat carrier that was snug but secure and set about trying to learn what kind of bird it was and how they could help it. Sheila’s parents are birdwatchers who live in Park Falls, Minnesota. She sent them some photos in hopes that they could help with the ID. “That’s a loon!”, they announced with equal parts excitement and concern.

The Florida Fish and Game contact they spoke to informed them that a loon would not do well in captivity and that they should return the bird quickly to where they had found it. Dutifully, the friends walked back to the beach. Night had fallen in the hour or so since Crater had first captured the loon. Knowing that coyotes and raccoons prowled the beach at night, they decided to place it higher in the dunes than it had been at first. That seemed safer.   

Still, they worried about the loon sitting exposed in the darkness. The bird had not tried to get away from them after they placed it back on the sand. And when they went back to check an hour later, it had not budged. At that point, Kimberly volunteered to take the bird for the night.

Back at home, Kimberly wracked her brain to think what was wrong with the animal. Was it weak from hunger? Knowing that its diet was mainly fish, she offered it the only fish she could – some tilapia filets from the fridge — on a small plate. The loon showed no interest. She looked at the clock and realized that it was 10 p.m. Whatever they were going to do for this loon would have to wait until the next day. She turned the lights out, draped a sheet over the carrier, and hoped it would get some rest.  

The next morning Crater and Kimberly strategized again about the bird. It looked pretty healthy and fiesty, they agreed. They could see no reason to hold onto it any longer. Together they decided to return it to the ocean.

The two friends took the carrier to the beach and removed the loon. This time, though, they let it go at the water’s edge, where the waves were breaking on shore. With furrowed brows and hands on hips, Crater and Kimberly watched as the bird bravely faced the waves and began to crawl towards the ocean. It was not pretty. On five occasions, a wave caught the loon and hurled it backwards several yards towards the beach. Kimberly was reminded of videos she had seen of tiny sea turtles heroicly battling the surf to reach the sea after hatching. The bird did not give up, however. Eventually it was able to take advantage of a lull between waves, reach water deep enough for a dive, and plunge beneath the crashing surf. Kimberly and Crater cheered to see its head pop up thirty yards from shore, well beyond the surf zone.

After a late March sojourn with beach-going humans, the loon, which we had banded the previous summer on West Twin Lake in north-central Minnesota, was back where it belonged — and looking none the worse for wear. We have no idea what brought this nine-month-old to shore.

We got a second, more sobering glimpse into the Great Void in late August 2025.

Battered by stiff winds and high waves from Hurricane Erin, the loon sat within the surf zone on Rockaway Beach in Queens, New York, twelve miles southeast of the Statue of Liberty. Waves crashed over it — even submerging it entirely on occasion. Susan Garman and her ten-year-old son Justin had made a quick trip to the shore to gawk at the surging whitecaps. But when they spotted a large bird that was being pummeled by waves and seemed unable to help itself, their light-hearted jaunt to marvel at nature’s fury took a serious turn.

They hurriedly shed their shoes, waded into the surf, and approached the bird. It looked as bad as Susan had feared it would: dazed, bedraggled, and water-logged. Worse still, the bird showed little fear of Susan and her son when they approached it. “You’re hurt, aren’t you?” she said to the animal, a comforting, motherly tone in her voice. “We are going to help you”.

Yet after she had gathered the bird up, Susan’s concern deepened. She had hoped to feel a smooth, reassuring mass of pectoral muscle when her fingers reached around its chest and belly, but instead, she encountered the sharp protruding keel of its sternum. So it was also emaciated. “Oh, buddy, I am so sorry!”, she whispered. It lifted Susan’s spirits slightly to see that the bird had four bright color bands on its legs. Her mind now racing, she reasoned that the person who had marked this bird would surely wish to help them save it.

She and Justin carried the bird to their home to do what they could. They nestled it in some blankets in the kitchen; it made no objection. Susan Googled “injured bird”, and found some local rehabbers and veterinarians, but no one that she reached could or would help. Justin submitted a photo of the bird to Google Lens to try and identify it. Lens came back with: “The bird in the image is a Common Loon.” “A loon!”, Susan repeated, trying to square her recollection of that glamorous northern species with the unsightly mass of soaked, tousled feathers on her kitchen floor. She and Justin were cheered by their ability to identify the bird they had rescued. They finally seemed to be getting somewhere.

But the loon was very weak and slipping away. “We are here with you”, was all she could muster, her voice softer and breaking from sadness and frustration. Finally, the loon stretched its head forward for a moment, pulled it back again to rest on its chest, and let out its last breath. Crushed by the loss herself, Susan looked for a positive to share with her distraught son. “At least it did not die alone”, she offered.1

We will have to record many more encounters of our young marked loons before we can shed much light on the alarmingly high mortality of loons during their first few years of life. Meanwhile, I am keeping my fingers crossed that other loons of ours who are in need of aid find such generous, compassionate people as these two youngsters did.

1 – We had banded the loon that Susan and Justin found as a chick on Upper Hay Lake, near Pequot Lakes, Minnesota, in July of 2024. So it was just over a year old when it perished. From the work of Kevin Kenow and his team, we know that loons from the Upper Midwest that winter off of Florida make their way up the Atlantic coast to spend the summers of their first and second years of life as far north as the Gulf of St. Lawrence. Thus, this young bird was probably on its way back to the wintering grounds in Florida.

Our paper on the Silver Spoon effect in loons has just been published online. You can read it at:

https://link.springer.com/article/10.1007/s00442-025-05836-8?utm_source=rct_congratemailt&utm_medium=email&utm_campaign=oa_20251124&utm_content=10.1007/s00442-025-05836-8

The top photo is of the loon from Panama City Beach, Florida. Photo by Jim Anderson.

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Following a long summer of capture, marking, and field observation, we have a new tranche of loon data from Wisconsin and Minnesota. The picture in Wisconsin does not change greatly from year to year. There we already had 32 years’ worth of research findings before 2025. But each successive year in Minnesota — where our research began in 2021 — increases our understanding of that population immensely. And with our improved knowledge of Minnesota loons, the status of the loon population across the Upper Midwest is coming into focus.1

Three demographic parameters together dictate whether a population of animals is increasing, decreasing, or stable, These factors are: 1) survival of breeding adults, 2) reproductive success, and 3) young adult survival. Recent measurements have shown us that the Wisconsin population is declining. And we know very well which of these parameters is responsible for the decline. If we compare our growing dataset in Minnesota to the trove of data we have from three decades of research in Wisconsin, we can learn whether or not Minnesota loons are headed in the same direction.

First, let’s look at survival of adult breeders. It should not be surprising that the most important single indicator of population dynamics (i.e. whether a population is stable, increasing or decreasing) is the rate of survival of its adult members. There is good news from the Wisconsin Study Area. The survival rates among territorial females and males both have been stable for the past three decades (Figure 1). This finding implies that once loons reach adulthood, they survive and hold their territories well. The decline that we are seeing in the Wisconsin population, then, must come about because of problems that occur before loons settle on territories.2

Figure 1. Annual survival rates of adult breeders on territories.

What about survival of territorial breeders in Minnesota? From measurements in 2022, 2023, and 2024, it appeared that adult survival in Minnesota might be lower than that in Wisconsin (look at these years in Figure 2, below). However, each year we get a better “read” on these numbers because our sample of loons becomes larger and more representative of the overall population. So the 2025 adult survival numbers are the most reliable ones we have to date. As you can see from Figure 2, there is no evidence for a

Figure 2. Survival rates of adult breeders in Wisconsin and Minnesota from 2022 to 2025. (Sample sizes are shown above each bar.)

difference in survival rates of territorial adults between Wisconsin and Minnesota. Minnesota, like Wisconsin, is seeing good adult survival. Again, this is good news!

Now let’s turn to reproductive success in the two states. Since we learned recently that the silver spoon effect is strong in loons, we know that we must look both at quality and quantity of loon chicks produced to get a good sense of how well a population is reproducing.

First let’s look at quantity. As Figure 3 shows, chick production in each region fluctuates greatly from year to year according to ice out date, severity of black flies, water clarity

Figure 3. Chicks fledged per territorial pair since 1995 in the Wisconsin Study Area and from 2021 to 2025 in the Minnesota Study Area. (Dotted line shows the trend in Wisconsin.)

in July, and other factors. Overall, however, chick production has decreased significantly in Wisconsin during the past three decades. Adult breeders are simply not producing as many offspring now as they did 30 years ago.

While Wisconsin data show a clear decline in number of chicks produced, it is too early to discern a trend in Minnesota. Chick fledging rate simply bounces around too much from year to year to see a pattern. We can say that chick production is at a similar level in the Wisconsin and Minnesota study areas. However, note that 2025 was a banner year for chick production in Minnesota and a poor one in Wisconsin.

Next we need to look at the quality of loon chicks that Wisconsin and Minnesota are producing. Our recent work has shown that chicks that fledge at low weights are much less likely to survive to adulthood and produce chicks themselves than are their heavier peers. Chick body condition has been falling for the past few decades in Wisconsin (see Figure 4, below).

Figure 4. Average body condition (mass divided by age) of chicks in Wisconsin from 1998 to 2025 and in Minnesota from 2021 to 2025. (Trendline shows Wisconsin pattern.)

The five years of data we have on body conditions of Minnesota chicks are not as many as we would like, but the numbers are consistent. Chicks fledge in Minnesota at similar — or even slightly worse — body condition than those in Wisconsin (Figure 4). We can infer that Minnesota is suffering from the same challenging chick-rearing conditions that have plagued Wisconsin (probably declining water clarity).

The third and final piece of the puzzle that we need to understand population dynamics is the survival of young adults. These birds are the breeders of the future that have not yet settled on territories. They range from three to about six years of age.

If you have been following my blog closely, you know that young adult survival of Wisconsin loons has seen the most dramatic decline among the three critical population determinants. That is, adult survival has held steady, and chick production has fallen somewhat, but the return rate of young adults to the breeding grounds has been abysmal — far below what it was a quarter century ago (see Figure 5, below).

Figure 5. Return rates of chicks to the breeding grounds 2 to 4 years after being banded as chicks in Wisconsin. (Data are missing for 2000 and 2007.)

We have been on pins and needles to see if this distinctive and rather alarming Wisconsin pattern is present also in Minnesota. Fortunately, our understanding of young adult survival has grown by leaps and bounds in Minnesota this year. Why? Because: 1) we started banding Minnesota chicks in 2021 and have done so every year since then, 2) most young loons return to the breeding grounds at three or four years of age in adult plumage, and 3) we regularly record identities of these young birds as intruders and loafers within our study areas. Thus, 2024 gave us our first glimpse at young adult survival in Minnesota using the crop of 26 chicks banded in 2021. And 2025 provided an even better window onto young adult survival there, since we could look at the return rate of 64 banded in 2021 and 2022 combined.

What do our findings show so far? In 2021, we banded 52 chicks in Wisconsin. Of these, 7 had returned as of 2025 (13.5%). We marked 28 chicks in Minnesota during 2021, and only one has so far been spotted as an adult (3.6%). For chicks banded in 2022, the numbers that have returned in Wisconsin and Minnesota, respectively, are 5 of 44 (11.4%) and 4 of 36 (11.1%).

These numbers tell a clear story. The percentage of young adult loons returning as adults in Minnesota is well short of that expected in a healthy population (a rate of about 41%). That percentage is also far below what we have seen in the past in Wisconsin (note the return rate in the 1990s and 2000s in Figure 5). In fact, the low return rate of young adult loons in Minnesota closely mirrors the dismal rate in Wisconsin.

In summary, it has taken five years to be confident of how the loon population in the Minnesota Study Area is faring. But our data now show that loons in Minnesota — at least those in Crow Wing and Cass counties, where we work — exhibit the same set of quirky demographic patterns that typify loons in Wisconsin and have set in motion a decline in the overall population there: 1) strong and stable adult survival, 2) poor reproduction in terms of both number of chicks and body condition at fledging3, and 3) a massive and diagnostic plunge in the survival rate of young adults (which are future breeders).

We have work to do.

1Thanks to Sheila Johnston, who took this photo of a molting adult loon on Gull Lake, which is just south of the Minnesota Study Area.

2I know. I just published a blog post in which I mourned the losses of many male breeders in the Wisconsin Study Area. I am still concerned about these losses. But in the long-term, which spans over three decades, adult males and females both have survived well. So I am hoping that the loss of several old, established male breeders this summer in Wisconsin was a blip.

3As noted earlier, it is too soon to tell from our data whether the number of chicks fledged is declining in Minnesota. We will gather those data over time. But we already know that Minnesota loon chicks are fledging in poor condition, just like Wisconsin loons. It is worth noting that the Minnesota Loon Monitoring Program, which has counted chicks across the state since 1994, reports a long-term and statewide decline in chick numbers.

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Loon calls seem to demand our attention. And sometimes they affect us emotionally. So it was this spring as I sat in a canoe with Sophia on the Blue Lake-West territory. While mopping up lakes after the pre-breeding census, we found the 16-year-old Blue-West female, W/G,B/S or “White-Green”, alone. Her behavior was ordinary, for the most part; she foraged, rested, and preened. Yet every few minutes, as if guided by an unseen hand, she lifted her head skyward and emitted a loud wail whose declining pitch seemed to convey profound and irredeemable sadness. Clearly her mate from the previous season was gone, and no male had stepped in to fill the vacancy. Indeed, White-Green spent the spring alone and still had found no partner in mid-June, long after the window for nesting with a new mate had closed.

White-Green was not alone in her solitude. On the following day Korben and I found the female on Hilts Lake, “White-blue-Silver”, nervously hanging out in the northwestern corner of that small lake. She foraged cautiously, unable or unwilling to drive off an intruder that foraged at will in her territory. She too found no mate with whom to breed this year. Having observed two openings for male breeders at the beginning of the year, I started to wonder if I was seeing a pattern.

I was chagrined to observe one of my favorite males, Green over Green, White over Silver (i.e. G/G,W/S or “Green-Green”) caught up in the male troubles that seemed to typify 2025. In 2015, when he took over Flannery, he created headaches for the resident female, who was rearing a chick on her own after losing her mate suddenly. But in the decade that followed, Green-Green became the steady, unflappable presence that his father was on Townline1. I smiled each time my schedule called for me to visit Flannery, knowing that I would get to check in on this tame, accepting male. But this spring, a few days after finding males missing on Blue-West and Hilts, I failed to locate Green-Green on Flannery. Instead, I followed his mate as she foraged throughout the lake. Every few minutes, she wailed pitifully — just as the Blue-West female had done. I took her behavior as a sign of Green-Green’s likely disappearance. A week later, however, Anna found Green-Green on Flannery behaving normally but reported that his left eye was cloudy. He remained on Flannery for the next month. But on July 13 he was found incapacitated by lake residents. Linda and Kevin Grenzer captured Green-Green and took him to REGI for treatment. Nine days later he seemed recovered and was released on Boom Lake. That was the last we heard of him until three days ago, when I got a report that his carcass had been recovered on the north shore of Washington Island on Lake Michigan. His presence there showed that he had recovered well enough to make a long flight east in preparation for his southward migration. We cannot be certain how he died, but his neck had a deep wound, which might indicate a prop strike. Life moves on, of course, but I am not looking forward to my next visit to Flannery, as I used to.2

The news was even more disheartening for the North Two male, “Red-Blue” (R/B,Ts/S). This tame 18-year-old loon — a veteran breeder that claimed the lake in 2014 — beached himself in early July. Linda and Kevin netted Red-Blue and took him to REGI also (see photo above, courtesy of REGI). He did not look terrible at capture, except that his right wing drooped. But he slid downhill rapidly and passed away within two days. The sudden appearance of necrotic tissue without other symptoms led REGI to conclude that he might have been electrocuted, perhaps through an ungrounded wire associated with someone’s dock lights. Naturally, his death was another blow. Despite the dearth of good nesting habitat on North Two, Red-Blue had raised four chicks during his eleven years on the lake.

Bad news comes in threes they say. So it was with a sense of inevitability that I learned recently of the third death of an established male during the breeding season in Wisconsin. G/S,Ar/Y (“Auric Red-Yellow”) was a skulker. My memories of Auric Red-Yellow are chiefly from capture nights. His was the ghostly black and white form that would take shape in the distance at night after we had motored slowly down sinuous, weed-choked Jersey City Flowage and spotlighted what seemed like ten thousand mallards lurking in patches of lily pads. But he was a successful parent, having fledged nine chicks with his even-more-skittish mate: Silver over Pink, Green over Green. Auric Red-Yellow was found dead on shore and emaciated, having ingested some form of metal. A vet must confirm this, but it seems that he swallowed someone’s lure, lost the ability to feed himself, and died of starvation.

Preoccupied as I have been with loon capture and marking, wrapping up the field season, and starting a year-long sabbatical, I have had difficulty processing the flurry of male mortality. I hope that the three males lost mid-season will be replaced by youngsters who had been waiting for their chance. After all, that is the way of things. Yet loss of male breeders does not always happen smoothly — or at all. The disappearance of our much-beloved male, Clune, from Linda Grenzer’s home lake in spring 2023 has resulted in three years (and counting) without a breeding pair on Muskellunge Lake.

In fact, I find this recent loss of five established male breeders profoundly unsettling. I have pointed out before that males are the limiting sex in loons. That is, males live shorter lives than females, and this tilts the adult sex ratio towards females. Put simply, males are in short supply, while there are ample females to fill breeding positions. Males have also been impacted by loss of water clarity. They, like chicks (and unlike females) are of substantially lower mass now than 20 years ago. As the “weak link” in the population, males seem most likely to be the cause of further population decline. Does the loss and lack of immediate replacement of these males this past season signal the beginning of that downturn? I hope not. But the pitiful wails of the solitary Blue-West and Flannery females after losing their mates made this year’s loss of males especially poignant and the memory hard to shake.

1Although there are many finalists for the honor, my all-time favorite loon was the old Townline male, Silver over Red, Orange over Green (S/R,O/G). “Orange-Green” was a doting dad who cranked out 20 chicks with five different females during an incredible 24-year run on his tiny lake just west of Rhinelander. Banded as an adult in 1994, Orange-Green seemed uncertain at first about his role on the Loon Project. Each time we launched our canoe and approached to take data he would eye us suspiciously for a moment and then relax, as if recalling that we were just those canoeists that liked to hang around with him and his family during the summertime. I was sad when Orange-Green did not return in 2018.

2The only good news to report regarding this episode is that another local male — this one an eight-year-old who was raised on Emma Lake and who made failed nesting attempts on Sherry and Hook lakes recently — is showing signs of claiming Flannery for his own and settling in with the breeding female. If he does so, the Flannery female — a pleasant, tame individual whom we banded as an adult in 2021 — will have no more reason to wail.

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There are several moments each year when I find myself out on a lake at night during capture season and suddenly think I must be insane. One such moment occurred at about 2 a.m. last night in Minnesota. Richard was driving the motorboat; Owen and I were perched in the bow scanning for loons. We swept the spotlight back and forth, back and forth across the dark surface of East Fox Lake. But we spent very little time in contact with loons. Our spotlight mostly caught dense, swirling tendrils of fog hanging in the air. Occasionally we broke free from this suffocating cloud for short intervals and the spotlight suddenly gave us an unobstructed view of 100 yards in every direction. Fortune was not on our side, however. We saw no loons in parts of the lake that were free of fog.

Loon capture — even loon-spotting — seemed highly improbable under these circumstances. I looked back at Richard behind me and Owen to my left. Their presence somehow reassured me that what we were doing — trying to locate a family of diving birds in total darkness and pea soup fog on a 241-acre lake so that we could lure them close to the boat with imitated calls and scoop them up in a muskie net — qualified as rational behavior. We searched on, fruitlessly. “Kill the motor Richard”, I said finally. “Let’s try playbacks.” Yet the loon pair at East Fox-South and their two 7-week-old chicks did not give away their position by vocalizing in response to our crisp recordings of wails from Maine and yodels from Michigan. Maybe it was regional bias.

We continued stalking the silent loon family. I directed Richard to steer right or left, so as to remain within the loon pair’s favorite part of the territory. Fifteen, twenty minutes passed. As our hopes of finding the family were beginning to fade, we caught sight of two black loon heads ten yards apart, partially obscured by a fog bank. “We need the unbanded male”, I reminded Owen. “Okay”, he whispered good-naturedly. With the two adults separated, we could not determine which was larger, forcing a split-second decision. Owen spotlighted the nearer adult. As we drew close to the bird, however, we realized our mistake. “Banded!” we both shout-whispered simultaneously. Owen swiveled the light quickly to the male we wanted. We crept up to him, while I imitated the scratchy whistled call of chicks in an effort to freeze him on the surface. At first, we were hopeful. The male did not shrink from the spotlight, as many loons do, and he was interested in the chick call. Alas, though, he was an unpredictable diver. He remained near the surface where Owen could track him with the spotlight, yet he swam first at — then underneath — the bow of the boat. I could not get the net in the water to catch him. After a minute or so, he vanished into the mist.

Moments later, the female wailed to our left. “Let’s go for her”, I told him, and soon after I had scooped her into the boat and — with Richard’s help — Owen had tucked her neatly into a padded, ventilated box. “Maybe the male will find the chicks”, I said hopefully. It was a reasonable expectation. We had seen the sole parent seek out the chicks many times before, once we had removed its mate from the water. And an adult swimming with its chicks is usually highly protective of them and less apt to dive. But we did not blunder into the male and chicks after that first encounter, despite 20 more minutes of puttering around in a cloud.

We gave up, motored to shore with the female, took a feather sample and blood drop, weighed her, and released her off shore. It had been a frustrating middle of the night boat ride on East Fox. We had failed to catch the bird we had targeted on the South territory. Yet we had banded four new chicks earlier in the evening — including two on socked-in East Fox Lake — and recaptured three adults. That brought our two-state tally to 40 unmarked adults newly banded, 88 chicks banded, and 27 adults recaptured. Looking back, we had quite a lot to show for our labors this July, considering that we face variable weather conditions, unpredictable study animals — and engage in an enterprise that seems to verge, at times, on outright insanity.

Pictured are Cora from the Minnesota team and Korben from the Wisconsin team.

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Twenty years ago colleagues and I published a paper showing that artificial nesting platforms increase loon’s hatching success by 70%. Others have reported similar patterns. So there is no doubt that, on average, loons that incubate their eggs on artificial nesting platforms (“ANPs”) put more chicks in the lake than do pairs using natural sites. Moreover, our paper showed that greater hatching success produced by ANPs also leads to more fledged loons.

In the last two decades, ANPs have become an enticing tool used by loon conservationists to boost loon populations. This is not surprising. ANPs have proven to be effective, and they are rather easy to make and place in the water. So conservationists can plop a mess of ANPs in the water and feel pretty confident that they have added young loons to the population. And they can make a strong case to funding agencies that their actions might help loons avoid population decline. Indeed, many millions have been/are being spent in the U.S. to float ANPs as a means to mitigate the negative effects that oil spills in the Gulf of Mexico have had on the species.

Are ANPs really just as good as natural sites at producing young loons that reach adulthood? Or are platform-raised chicks not as likely to survive to fledging age as chicks hatched as natural sites? We must remember that loons pick the location of a natural nest, whereas humans choose the site where platforms go. So it seems quite plausible that platform-raised young face hazards that natural-raised young do not.

It is only now that I have large enough samples of nests from platforms and natural sites that I can run a head-to-head comparison. Despite my 32 years of Wisconsin data, only a small proportion of loons in the Wisconsin Study Area (e.g. 15 of 90 focal pairs in 2024; 17%) nested on platforms. In Minnesota, however, almost half of all of our focal pairs use ANPs (38 of 84 territorial pairs in 2024; 45%), so our sample of platform-hatched chicks has swollen markedly since 2021.

As the graph above shows, hatchlings from platforms are lost slightly more often than are natural-hatched chicks in both states. While the pattern shows up in both Minnesota and Wisconsin, the difference is quite small and does not reach statistical significance. In other words, we have no scientific evidence that chicks hatched on platforms suffer lower survival than those hatched at natural sites. The same can be said for chick loss in Wisconsin versus Minnesota, despite what appears to be a slightly higher rate of chick loss in the North Star State.

Frankly, I am relieved! It has become almost de rigueur to place an ANP in your lake to support the loons. If, for some reason, ANPs had been producing chicks likely to perish before reaching adulthood, it would have sent shockwaves through the world of loon conservation.

I am still not a great fan of nesting platforms. Why not? Because we have learned in recent years that nest predation is not the main problem loons are facing in the Upper Midwest. Remember, nesting platforms are a one-trick pony. They increase hatching success enormously and put more chicks in the water. But if chicks cannot get enough food to survive to adulthood or reach prime condition, then all of the platforms in the world will not help them.

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I am a nervous traveller. The day before I am scheduled to leave, I start to worry what could go wrong. Could I miss my flight? What personal items will I forget to pack? Which tasks on my to-do list will I leave unfinished?

So it was two days ago as I drove from the house where I had been staying to meet up with my Minnesota field team before flying home to California. I had spent the morning collecting data on territorial loon pairs — six on Ossawinnamakee, and one each on Fawn and Pig Lake. I relish every moment spent with loons, especially when I am on my own. But anxiety about getting my field work done, entering my data, and tidying up the place before my departure gnawed at me all day.

I tried to work backwards. Arrive at Brainerd Airport at 5:15, so leave from storage box at 4:30. Be at storage box by 4:00 to pack up canoes and check banding supplies for next month. Arrive at tech’s lodging by 2:30 to review field procedures and check in before my trip. Finish entering data in online database by 1:30. Tidy up lodging by 1pm. Leave my last study lake by noon.

When I set off to visit my techs on Ossie, I was still on schedule. As I began to round the hairpin curve on County Road 39 next to the Ossie boat landing, I thought: I just might make my flight. In a brain-staggering moment, though, I spotted an adult loon sitting on the shoulder on the east side of the highway displaying a clear intention to cross. “Oh no!”, I screamed, as I pulled to the side of the road and flicked on my emergency flashers. I ran across the highway and placed myself in the middle of the northbound lane, intending to block any traffic from passing close to the loon. As I crept cautiously toward this adult, I noticed two newly-hatched chicks huddling against it, trying to shield themselves from my view. “Oh no!”, I repeated.

Despite my shock at the loons’ predicament, I understood immediately what was happening. Six hours earlier Keith and Dawn Kellen had given me a tour of the six breeding pairs on Ossie. The Ossie-Muskie Bay pair had stumped us all spring. The Kellens had seen them together early in the year, had seen only one out on the water on multiple occasions thereafter, and yet neither they in their pontoon nor my team in our canoe could find a nest in the far east bay of the lake, adjacent to County 39. The pair had simply vanished. The sudden appearance of an adult and two small chicks told me that they had not nested on Ossie, where we had been looking for them, but on Rat Lake,

Location on County Road 39 where I found the adult male and two small chicks.

across the highway from Ossie’s eastern end. Thus, the Muskie Bay pair was in the awkward situation of seeking to nest on one lake and raise their chicks on another. That ambitious plan set them up for a difficult land crossing.

I had stumbled upon the loon family at the most dangerous point of their overland journey. The adult wailed and tremoloed as I stood in the highway 30 feet away. A southbound car and truck slowed down to rubberneck but continued by despite my frantic waving for help. My mind raced. I could not handle all three loons. If I picked up the adult, its flailing might injure the tiny chicks. Furthermore, the chicks might decide to strike out on their own across the road without their parent to guard them. I was not sure that I could discourage them from putting themselves in harm’s way while holding the adult.

Knowing that the field techs were a few minutes away, I pulled out my phone. “Call Owen”, I demanded of Siri. Owen answered in his calm baritone. But I screeched, “Drop everything and come to the Ossie boat landing. There is a loon here in the road, and I need your help!”. “On my way”, he responded.

While I waited for Owen, more southbound vehicles came by, each carrying a driver wearing a puzzled expression. But no one stopped. As I was debating the odds of getting help from a stranger, the panicked adult abruptly turned, lined himself up with the roadway, and began to run down the highway with wings flapping, leaving his chicks with me. I watched and listened in horror as his feet repeatedly thwacked against the hard pavement during this takeoff attempt and was relieved when he aborted it and skidded to a stop about 40 yards away in the southbound lane.

At that desperate moment, Mitch Carlson arrived in his pickup with his friend, Leo, and stopped in front of the grounded adult. Sensing that the window to save the loon family was closing, I scooped up the tiny chicks and marched hastily in Mitch’s direction (see photo below). He opened his door and looked at me questioningly. “Can you take the chicks?” I asked. “Okay”, he replied quickly, sensing my urgency and smoothly accepting them. He volunteered, “My wife raises chickens!”. I turned my attention to the adult in the road.

After his aborted takeoff attempt, the male loon sits in the southbound lane of County 39 while I approach carrying his chicks. Photo by Mindy Schenck.

Quick, decisive action yields the best results when capturing animals, I have found. When I drew close enough, I lunged at the rearing adult and managed to grasp it. I then folded its wings against its body, held it to my side, and did my best to fend off its bill. Meanwhile, Owen had arrived. I struggled towards the boat landing with him guiding me. Mitch followed with the chicks, while Leo walked alongside, gawking and snapping photos.

The chicks were so small that I was afraid the adult might leave them behind in its haste to put distance between us and himself after release. So I asked Mitch to let the chicks go, waited a moment, and gently

Mitch holds the two newly-hatched chicks moments before we release them at the Ossie boat landing. Photo by Leo Carner.

lowered the adult — which felt like a male based on size and ornery demeanor — into the water at the end of the boat landing. Fortunately, he dove, surfaced quickly, spotted the chicks, and promptly resumed his parenting responsibilities. It was an ample reward for Mitch and me to see them all together so quickly again in the middle of the lake.

The male and chicks reunited quickly after we let them go off of the Ossie boat landing. Photo by Leo Carner.

I will always be a nervous traveler. I do not think one outgrows that. And I need to put a schedule together to convince myself that I can meet a deadline. But perhaps on my next trip I will remember to include 30 minutes of wiggle room for unforeseen events.

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We face many difficulties in studying loons. They are aquatic. They dive and resurface far away when we approach them. They are gone for half the year. We can capture and mark adults only during a brief window when chicks are small. We cannot keep them in captivity, which limits what we can learn about their biology. Finally, loons are long-lived, so it requires decades to understand their life histories fully.

Back in 1993, when I informed her that I was about to begin a loon study, my postdoctoral advisor at Indiana University made a face. “Are you sure?”, she said. She was well aware of the difficulty of studying species like whales, eagles, tigers, and loons. These are beautiful, charismatic animals. But they are challenging to learn about scientifically. Was it wise for me, a young untenured academic, to embark upon a long-term investigation of a notoriously recalcitrant species?

No, it was not wise. But wisdom does not always guide our decisions. I felt drawn to loons. I also believed that the training I had received at Indiana, at Purdue, and especially from Haven Wiley, my PhD advisor at the University of North Carolina, had equipped me to ask rigorous, meaningful questions about the behavior of any animal.

When I first began my work in 1993, I recognized immediately that my greatest obstacle was going to be telling loons apart. This problem is familiar to behavioral ecologists. I had confronted it myself when studying wintering white-throated sparrows in North Carolina in the 1980s. But treadle traps allowed Haven and me to band hundreds of white-throats and recapture them at will. Moreover, we could see the bands on sparrows’ legs at all times.

Not so for loons. In most cases, we cannot identify an individual when it is resting on the water. Even when we have nailed the bands on both members of a breeding pair, we must reidentify each bird when it dives and resurfaces. (Every so often a loon has an oddity in its plumage or on its bill that sets it apart from other adults.)

Loons themselves must be far better at identifying others of their species than humans are. After all, if humans lose track of which loon is which during an observation session, we curse and make a few erasures on our datasheet. But a loon that mistakes an intruder for its mate might pay for the error with its life.

So it was with more than casual interest that Anna Alber and I entered the second phase of our analysis of loon appearance by computer. Could a computer learn to tell a large sample of loons apart visually? If so, then surely loons themselves can tell each other apart. A loon, of course, can base its identification not merely on appearance, but also on behavior and vocalizations.

Anna ran two trials. First, I identified 10 loons from Wisconsin and Minnesota for which we had at least 24 photos from a range of angles. Anna chose a set of “test” images of each loon in the sample and set them aside. She then “trained” the program to identify all 10 loons, using the remaining images. Upon testing, the computer correctly assigned 85% of Anna’s test images to the proper individual. Considering that pure chance would have resulted in a success rate of 10%, 85% seemed pretty good. In the next trial, we used 35 banded loons. This time I picked one test image for each loon, trying hard to select ones that closely resembled no other in the sample. In this go round, the program correctly identified loons at a 68% rate. Since random guesses would have resulted in a 2.8% success rate (1/35), Anna and I have begun to think that the computer knows what it is doing.

We found two additional patterns that shed light on the use of AI to identify loons from photos. First, in the cases wherein the computer correctly ID’d the loon in the test photo, it had 18.7 images to practice on beforehand, whereas the mean number of photos for misidentified loons was 11.5. In other words, when the computer had developed a good sense of what a bird looked like, it was better able to identify that loon later. Second, the computer was good at predicting its errors. In the 24 cases where it had ID’d a loon correctly, the computer’s average certainty of its guess was 81%. In contrast, the mean certainty of the computer for photos where it misfired was only 53%. And if we narrow the sample to instances when the computer had 90% certainty or more, it was right 12 of 12 times.

There is more work to be done in identifying loons from their photos. Phase Two, happening this year, will be to take photos of as many loons photographed last year as we can to see if the computer can use photos of a loon in one year to identify it in another year. This, of course, recreates the problem that male and female breeders across the Upper Midwest faced a few weeks ago when they returned to their territories and encountered an individual of the opposite sex. “Is that you?”

The photo above is by Hayden Walkush and shows the long-time male breeder on North Two Lake, near Lake Tomahawk, Wisconsin. Hatched and reared on Hodstradt Lake in 2007, this male settled on North Two in 2014 and has fledged four chicks on the territory since then. The Wisconsin Team found him back on North Two this past week, so he is back for another go!

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I love southern California. I truly do. Although it is disconcerting to look outside — or even step outside — and never really know what the season is, the weather is always beautiful here. The beauty of the region pales for me a little this time of year though. Why? Because we get curious, muted springs. True, Orange-crowned Warblers, House Wrens, and Bell’s Vireos have exploded into song. But it is only slightly warmer now than it was a month ago — and barely greener. The spring that I read so much about in the paper each day must be going on elsewhere.

Indeed it is. With ice off of our study lakes in Wisconsin and Minnesota, loons have returned to their territories. Most are reacquainting themselves with their mates of the previous year after eight months apart, foraging to recoup energetic losses from migration, and checking out potential nest sites.

But rest and recovery are not the only orders of the day for territory holders. The few weeks after iceout are a time of great peril. Young loons without territories probe those in their neighborhood for vacancies and weakness. These young adults try especially hard to seize territories where they observed chicks the year before. (Chicks on a territory are like a badge signalling its quality.) Breeders intent on holding their territories must invest considerable effort convincing young pretenders that an attempt to evict them would be costly and futile. Providing ocean conditions on the wintering grounds a few months before allowed them to prepare well for the breeding season, most territory holders do ultimately hold off all competitors and turn their attention to breeding.

Loons are not the only ones scrambling. With classes still in session until May 16th, I am stuck in California for two more weeks. While my Wisconsin and Minnesota teams are prepping for fieldwork, I am completing an endless stream of forms, contracts, online trainings, and other paperwork to help bring that about. On weekends, my wife and I ride our bikes toward the ocean and take in the mild greening and hint of warm weather that mark springtime in this part of the world. Yet a big part of me hungers to be on northern lakes, where spring arrives with a vengeance and loons fight tooth and nail for the privilege of rearing young for another year.

Sheila Johnston’s cool photo from this spring shows her favorite loon, Lena. Lena was a victim of an early-season eviction last May and spent weeks recuperating. We are delighted to see her back this year and re-paired on her old territory. With some luck, she and her mate will raise chicks on Upper Gull in 2025, just like the old days.

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In recent blog posts, I made the point that the course of a young loon’s life is more affected by its early experiences in Wisconsin or Minnesota than by conditions during its first winter in Florida. Winter happenings along Florida’s Gulf Coast do affect youngsters, but the amount of food they receive in their first several weeks of life makes an indelible imprint on their well-being.

One might have expected established breeders to show even greater immunity to winter conditions. Once an adult has claimed a territory, reared chicks to fledging, and survived several trips from the Midwest to Florida and back, what challenge is left that can threaten it? Can’t adult loons begin to “coast” a bit after these achievements? And if so, might the four months spent along Florida’s shoreline simply be a period of rest and recovery from the stresses of territoriality?

To some degree, established adults can coast. Having settled on a breeding lake at the age of 6 years or so, they have surmounted life’s greatest obstacle. Since senescence does not take hold until they are in their mid teens or 20s and since annual survival of loons in their prime is 94%, newly-settled breeders stand a good chance of holding their territories for a decade or more. But long-term ownership is never certain. The simple act of raising chicks exposes an adult loon to territorial challenges, because nonbreeders bent on claiming a territory use the presence of chicks there as a badge indicating its quality. So proud parents in one year pay the steep cost of increased territorial defense — and the risk of eviction — the next.

Recently we have learned an incredible thing. Ocean conditions that loons face during winter — whether they are 8, 11, or 15 years old — can reduce their body condition subtly such that they are prone to eviction from their territories several months later, when they return to the breeding grounds. Specifically, loons that have spent the winter in cold, dilute ocean water are much more likely to get booted from their summer territories than those that spent the off-season in warm, salty water. Here is what those patterns look like.

Fig. 1. Territory holders that experienced cold ocean water during the previous winter are more likely to lose their territory in a battle than those that spent the winter in warm water.
Figure 2. Breeders that encountered ocean water of low salinity were more likely to be evicted from their territories than breeders that had wintered in salty water.

An obvious question is this. Why is warm salty water beneficial to loons? Sadly, the answer is not obvious, although loss of salinity can be linked to increased runoff from rivers into the Gulf of Mexico, which reduces water clarity and can spawn phytoplankton blooms. (Both low clarity and increased phytoplankton are harmful to loons.) The negative impact of cold ocean water is also hard to interpret, but cold water forces loons (and other warm-blooded aquatic creatures) to expend energy just to maintain a high and stable body temperature. Perhaps the energetic hit that loons face in keeping warm in a cold ocean puts them at a long-term disadvantage.

We are not the first to discover that environmental factors in one season can impact animals in another. In fact, such “carry-over effects” are now known in several species of songbirds. Understanding carry-over effects is crucial to conservation, because they reveal the interconnectedness of the seasons. If the quality of a bird’s winter habitat limits when it can migrate in the spring, how successful it is at finding a territory on the breeding grounds, and the number of offspring it raises, then clearly we must take a holistic view to understand avian conservation.

From a territorial loon’s standpoint, poor ocean conditions in winter pose yet another challenge. It is bad enough that raising chicks puts a great big target on your back. We now realize that loons that encounter cold, dilute ocean water during a winter after rearing chicks will face a double whammy in holding their territory the following spring.

Our discovery of carry-over effects in loons might help us understand how the species’ odd system of territory eviction evolved in the first place. Perhaps natural and inevitable fluctuations in the quality of the winter habitat guarantee that some adult breeders will be vulnerable to takeover each year. If so, winter-weakening sets the stage for the evolution of territorial eviction as an effective behavioral strategy for claiming a territory.

We eagerly await the 2025 field season and have a very strong team in both states. However, field costs have mushroomed unexpectedly by a whopping $28,000. As it stands, we are $1,800 short of our goal of raising $20,000 to earn an additional $20,000 in matching funds from the Walter Alexander Foundation. If you are able, please consider helping us cross this threshold so that we can defray most of our field costs. Thanks so much to those who have already given!

The beautiful photo of the male is one of Linda Grenzer’s. It shows the Deer Lake male (B/S,P/R) becoming airborne during a takeoff run. Love that pink band!