Among the most curious and talked-about aspects of common loon behavior are “social gatherings” — groupings of three to twelve adults that occur in July and August, which feature loons swimming together and interacting socially for an hour or more. During social gatherings, adults exhibit stereotyped social behavior, such as circle-dancing, bill-dipping, excited peering, and splash-diving. Occasionally one loon lunges at a second, which touches off a point-yodel by a male or two and fleeing across the water by a few panicked participants. If the gathering is on a territory with chicks, those chicks hide near shore, while their parents swim with their adult visitors. However, as shown in Linda’s photo (above; the observer is Nelson Gould, who spent two years helping run the Project) and my video (below), the most frequent and obvious behavior seen in social gatherings is what appears to be relaxed, slow, joint swimming by a large raft of adults. Peaceful swimming of this kind could be described as the hallmark of social gatherings.

Of course, it is tempting to offer a simple, unitary explanation for social gatherings. I have been asked a number of times whether the visitors at social gatherings might not be chicks that were hatched on reared on a lake and have returned as adults to re-connect with their parents. Setting aside the fact that young adults looking for a territory would seem to have little to gain from visiting their parents — and might even harm their parents by drawing more attention to the territory (see below) — we have many marked loons of all ages in our study area and can look at the number of times that young adults have revisited their natal lakes. Of 1743 visits to lakes by adults that we marked as chicks that we have recorded so far, only 13 have been visits to the natal lake. We have not yet run statistics on this pattern, but it seems clear already that young loons actually tend to avoid their natal lakes — intruding at many lakes in the neighborhood but seldom visiting their natal one.

A second common speculation is that social gatherings are mere aggregations of birds for foraging purposes. But, as Jim Paruk has noted, foraging rarely occurs at social gatherings. Finally, social gatherings are sometimes described as being groups that form in anticipation of migration; but gatherings occur in late summer, not fall, so they happen far too early to be a prelude to migration.

In fact, a crucial first point to grasp as we seek to understand social gatherings is that participants in these events comprise a hodge-podge of adults with competing interests. In other words, the key to understanding social gatherings will lie in understanding their makeup. Therefore, we will be powerless to solve the riddle of social gatherings without a large population of marked birds, including both territorial adults and young intruders.

The first set of participants in social gatherings are simply territorial pair members defending the lake where the gathering occurs. If this “home pair” has chicks, the intruders within the gathering are unwelcome guests, and the home pair’s chief goal is to steer the intruders away from their chicks and make sure they do not stay too long. Why? Because nonbreeding loons that are part of the gathering try to find chicks, use the presence of chicks as a badge indicating the quality of the territory, and often return to evict owners on lakes that produced chicks the previous year. Home pairs that have failed to produce chicks probably also benefit from limiting the duration of gatherings, so as to protect their territorial position. (However, we have not verified this last hypothesis statistically.)

A second set of participants in social gatherings — the largest segment — are nonbreeders who seek information for future territory settlement. Unlike others who have tried to explain social gatherings, we on the Loon Project are in a unique position to describe this important segment, because we have been marking chicks in our study area for over twenty years and these marked chicks have returned as adult nonbreeders in many cases. Thus, we know that nonbreeders are: 1) adults two to four years old that are too young to settle on a territory, or 2) individuals five to ten years old that are in prime condition and on the brink of territory settlement, or 3) adults of various ages that have been evicted from a previous territory and are looking to resettle on a new one. Again, all nonbreeders have in common that they are learning about a variety of territories in a certain region — chiefly which have chicks; which do not — in order to settle on one of them, usually by evicting a territorial owner. So nonbreeders are a particularly dangerous segment of the loon population, from the standpoint of home pairs.

The third cohort of attendees, and perhaps the most interesting, consists of neighboring territory holders. These adults, which may or may not have chicks on their own territory, at least have a territory and therefore obviously have reasons very different from nonbreeders for joining the gathering. Since they have left their own territory undefended to make the flight to this neighboring lake — and often their chicks, as well — it seems clear that neighbors must gain something from the visit. The most plausible explanation for participation by neighboring pair members is that they are trying to draw nonbreeders in the neighborhood to someone else’s lake instead of their own. Neighbors seem to be exploiting the fact that adult loons of all stripes are strongly attracted to other adults that they see on lakes. In decoying nonbreeders to another lake near their own, neighbors are decreasing the odds that their own chicks hiding back on their lake will be discovered, while increasing the chance that the home pair’s chicks will be seen by nonbreeders. From the home pair’s standpoint, then, neighbors are competitors whose visit is potentially harmful in the long run, but at least they pose no threat to territory ownership.

I will have more to say about social gatherings. Indeed, I am currently analyzing and comparing the behavior of territorial pairs and intruders at social gatherings. So I will have further findings to share in the coming weeks. For now, try to keep in mind the key point of this post: loons in social gatherings constitute a broad swath of individuals that differ in age, territorial status, and current reproductive stage. Although the behavior of all participants might look similar during the gathering, each loon has its own goals in attending the event and its own hopes for the outcome.

In the interest of full disclosure, I will admit that I am grouchy. In the past five days, we have lost three adult loons from our study area. The first of these was the Arrowhead Lake male who, having broken his right wing in early July, finally succumbed to that injury last Friday, leaving his mate and two almost-grown chicks. We all knew that the Arrowhead male was going to die before the end of the season, but it still hurt when his lifeless body finally washed ashore.

The second loon that we lost was an adult male found in the eastern part of Minocqua Lake. He was unbanded, and the only unbanded male we know of from that location is the territorial male from the Minocqua-East territory, who nested unsuccessfully with his mate in the thoroughfare to Lake Tomahawk in May. So we are fairly confident that this male is from Minocqua-East. On Saturday he became incapacitated, beached himself near the Minocqua boat landing, was reported by lake residents, and was picked up in this defenseless condition by Linda and Kevin Grenzer, who took him to Raptor Education Group, Inc. Linda and Kevin could tell from his green droppings and lethargy that he was likely a victim of lead poisoning, and their suspicion was confirmed by a blood test at REGI on Saturday. The folks at REGI started chelation treatment to remove the lead from his blood, but their efforts were too little, too late. A large male weighing about 4.5 kilograms when he was healthy, he had wasted away to 3.1 kg at his death.

Male from Katherine Lake on Lake Michigan. Photo by Christopher Rocke.

The third death of a male loon from the study area occurred just a day later. On Sunday Chris Rocke e-mailed me to say that while paddle-boarding on Lake Michigan, he had run across a marked loon that stayed very close to shore (see his photo, above) and seemed reluctant to dive. He became concerned about the bird’s odd behavior and listlessness. Over the few days that Chris watched him, this loon became weaker and weaker, to the point where Chris was able to capture him by hand on Sunday afternoon. His bands, photographed by Chris, below, showed that he was “silver over red, taupe-stripe over red”, an individual that we have come to know well over the

years. First banded in 2004 on Lake Seventeen with his mate and two chicks, this male and the four females he was paired with during his breeding career on Seventeen cranked out eight offspring before his eviction in 2014. He then relocated to Katherine Lake, where he nested unsuccessfully for six straight years. This year, he and his mate failed in a way that we had not observed previously — first one of their eggs and then the other rolled off into the lake, because the nest had been placed on a slope near the water. Still, this male’s breeding success on Seventeen made him one of the most productive breeders in the study area. Like many loons from the Upper Midwest, he was making a stop on Lake Michigan prior to completing his migratory journey south.

Once I learned that Chris had found one of my oldest and most familiar study animals in a compromised condition, I urged him to take the loon to an animal rescue center. Chris and his partner, Leva Engel, interrupted their Labor Day vacation, drove the Katherine male over an hour towards Antigo, and dropped him off with Linda and Kevin Grenzer, who completed the trip to REGI. As the featured photo shows, it was deja vu for the Grenzers: another limp, lethargic loon. This condition, together with his greenish feces, pointed again to acute lead poisoning, a diagnosis confirmed by blood test. Like the Minocqua male that had died the day before, the Katherine male’s lead concentration was so high that it could not be measured precisely. The Katherine bird had wasted away from 4.4 to 2.8 kg in a period of a week or so, owing to his inability to feed himself. After several seizures yesterday (another symptom of lead poisoning), he passed away overnight.

If lead poisoning were a freak occurrence, like a lightning strike, we could justifiably shrug and move on. We cannot protect loons from lightning strikes. But a clear pattern has developed in northern Wisconsin: many adult loons die each year from acute lead poisoning, when they ingest lead sinkers, usually on fishing lines. Loons can survive ingestion of fishing tackle. In fact, their powerful digestive systems have been shown to grind up steel hooks and swivels. Lead is different. Lead kills loons, eagles and other wildlife that swallow it, because it has rapid, powerful effects on the brain and nervous system and cannot be quickly broken down or expelled by the body. And most loons that ingest lead fishing tackle are not reported by humans until they are so weak that even extreme measures taken by veterinarians cannot save them.

Consider this. We hear about only a fraction of all loons in Wisconsin that swallow a lead sinker and die quietly on a lake shore. Still, in the time since I started this blog, we have recorded five loon deaths (three just this year) from lead poisoning. I think it is time to see lead poisoning as less of a freak occurrence and more of a regular — and probably important — source of loon mortality. In New Hampshire, half of all recorded loon deaths in a 2017 study were caused by lead toxicosis. Even if we are far better off in Wisconsin, and only, say, 1/4 of all loon adults die from lead poisoning in our state, this seems like an unacceptable number. I say this because we can prevent deaths of loons, eagles, and other wildlife simply by using fishing sinkers made of bismuth, tungsten, steel, or other materials. In short, at a time when the population of loons in northern Wisconsin is already in trouble, why are we still using fishing tackle that kills loons?

John on Lumen Lake sensed something troubling about the loons on around August 13th. He noticed a burst of unusual calls, but he also saw that the chick was still alive, healthy, and being attended by an adult. So he was not sure what to think. As it turned out, the Lumen male was in a struggle for his life on Birch Lake, 2 km away, where he had gone to forage. His miraculous escape and recovery — and his mate’s ability to hold the fort and keep their chick alive during his absence — has become a rare feel-good story to report during a difficult year.

We are able to piece together this story from combined accounts of folks on Lumen Lake, Birch Lake, and our own team member, Lyn, who has generously remained behind in the study area and continued to gather valuable data on chick feeding patterns and survival. The story begins on August 11th, when Lyn made a routine visit to Lumen, found the male alone with the chick, and reported nothing unusual about the duo. Two days later, Mike Henrichs and his three grandkids, Jaden, Jesse, and Jordan, were out fishing on Birch Lake when they noticed an adult loon behaving strangely and found that it was dragging a bobber and fishing line. And here is the crux of the story. Instead of merely reporting the loon in distress to a local DNR office, which lacks the personnel to assist injured wildlife, the Henrichs decided to help it. They could see that the loon was not diving to avoid them, as a loon normally would, so they approached the bird, grabbed hold of the fishing line attached to its leg, and pulled it onto their boat. As their video shows, they then patiently cut the line off the loon’s leg, around which it had become tightly wrapped, dislodged a hook from the loon’s bill, and joyously released it. Everyone had a role. Thirteen-year-old Jaden helped her grandpa hold the bird, locate the line and hook, and release it; 9-year-old Jesse did the camera work, and 7-year-old Jordan endured frequent helpful tips from his brother and kept the boat off shore. The Henrichs were unaware of this loon’s current status and, naturally enough, presumed he was a resident of Birch Lake.

But we knew different. In fact, the entangled loon was not merely a floater, killing time until the fall migration; he was a father with a chick and territory to defend. His sudden entanglement and consequent inability to return to his breeding lake put his mate on Lumen in a bind. She became the sole provider and defender of their seven-week-old chick. Moreover, she was suddenly saddled with the task of fending off efforts of intruders to take over her territory without her mate’s help. We cannot be certain when the Lumen male took someone’s bait on Birch and became entangled in the attached monofilament line, but it was almost certainly sometime on the 11th or 12th, because the bird was quite weak and compromised by the 13th, when the Henrichs freed him. Thus, the female was on her own with her chick for at least two — but perhaps as long as nine — days.

Single parenting, as I have described lately, is no picnic for loons and usually has dire consequences. After the recent debacle on Arrowhead that forced a female there into a prolonged period of single parenting and will likely result in loss of one or both chicks, we were ready for a happier outcome. Still, I was dumbfounded to learn that Lyn had seen the disentangled male back on Lumen — seeming none the worse for wear — on August 20th. Her observation meant that the male had become hopelessly entangled, lost a good deal of strength, been caught and cut loose, and somehow recovered well enough to take off and fly back to his breeding lake within a period of nine days — in time to rescue his mate from her challenging stint of uniparental care. The key to the male’s survival and rapid recovery was no doubt that he was found by a calm, determined family within a few days of his entanglement, when he still had enough residual strength to bounce back and return to his own family.

How could a breeding loon’s desperate brush with death lead to such a heart-warming outcome? Simple. A thoughtful human family took it upon themselves to help a loon in distress. And the loon they rescued took full advantage of their generosity.

My family took a vacation this past week to the East Coast. It was not a typical vacation. We boarded our eastbound flights nervously, wiped our seats obsessively with the comically-small towelettes provided by flight attendants, cinched our masks high over our noses, and glared with disapproval at fellow passengers who failed to do the same. Upon arrival in Boston, my daughter and I waited for three hours in 96-degree heat for a COVID test (both were negative) and then rushed back to the airport to meet my wife and son. Ultimately, though, we all arrived in Vermont for a five-day vacation with family members who could also boast of recent negative tests.

Even without the added stress of coronavirus, I had expected to struggle on this vacation. I loved vacations when I was a child. My parents would throw their four kids into one of those monstrous Chevy station wagons with fake wooden side panels and drive northeast along the interstates from Houston on our annual odyssey to New England. We loved the highways, the motels, the afternoon stops for soda, singing madrigals in the car at night, playing the alphabet game with road signs — and even the adventures we had after occasional tire blowouts. But age has made me hunger for the sound nights of sleep that go with routine and a familiar bed. So when my wife described her plan for a New England holiday — to begin immediately after my daughter and I had buttoned up our canoes and car in the storage box in Rhinelander — I sighed. “Ok”, I said, “that sounds like fun!”.

Despite their many drawbacks, there will always be one big positive about vacations: vacations bring an exciting change of scene. In meeting new people and taking in new sights and smells, you are able to compare — consciously and unconsciously — your vacation spot to what you have seen elsewhere. As a scientist, I appreciate the new connections my brain makes when I move from one location to another.

As it turned out, our visit to Vermont provided an unexpected comparison of two loon populations headed in opposite directions. One of our outings took us kayaking on Kent Pond, near Killington. “Pond” is a misnomer; Kent Pond is a dammed lake that covers 71 acres. According to Eric Hanson, who has been following Vermont loons for almost as long as I have been covering those in northern Wisconsin, the first attempted loon nest on Kent Pond occurred in 2009, and the first chick fledged in 2011. So, Kent Pond — and southern Vermont generally — illustrates how loons can settle in an area, begin to breed, and establish a new population. After I had adjusted to sitting so low in the water and using the quirky two-sided paddle to propel my kayak forward, I joined my daughter and the rest of our party as they sought out the loon pair that inhabited the Pond. We caught up with the tame adults and their two nine-week-old chicks along the northeastern shoreline. The larger chick swam and preened casually and lagged behind the family, while the smaller chick approached and hounded its parents for food unceasingly. Their size and behavior made it clear that these were two strapping chicks. Their wing flaps, moreover, exposed fully adult-sized flight feathers that will soon lift them off of the Pond and permit them to explore other lakes in the area. (I took no photos of the Kent family, but Linda’s photo of a rare two-chick family on her lake is similar.)

After gawking at the two monstrous chicks on Kent Pond for a time, I explored the Pond a bit more and was reminded of one of my study lakes in Wisconsin. Like Kent Pond, Currie Lake is rather round in shape and has two small islands near its center. Like Kent, Currie also hatched two healthy-looking chicks in June 2020. But Currie lost one chick in its first week and the other chick before it reached two weeks of age. In other words, the chick loss this year at Currie exemplifies the current reproductive downturn in the northern Wisconsin population. The two adult-sized chicks at Kent, on the other hand, well represent the Vermont loon population, which continues to grow and expand. (Below is a plot of the size and breeding success of loons in Vermont from the Vermont Center for Ecostudies.)

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I am not a bitter person. I try hard to look without jealousy at those more fortunate than myself and be happy for their situation and not sad about my own. But those two big, fat, sassy chicks at Kent Pond — and the population of which they are a part — showed me a portrait of loon ecology that is becoming distressingly unfamiliar.

I feared in May that 2020 would be a forgettable year for breeding among loons in northern Wisconsin. As many followers of the blog may recall, I wrote numerous posts this spring and summer warning of reproductive struggles of loons in Oneida, Lincoln, and Vilas counties. Before I was even able to visit my study lakes in late May, the die was cast. Black flies, Linda told me in early May, were worse in 2020 than any year during the 28-year study — worse even than in 2014, when about 80% of all first nests were wiped out by the relentless blood-suckers. Indeed, only 3 breeding pairs out of the 109 that we followed this year were able to incubate to hatching a nest that they began in May. The flies were a painful punch to the gut from which the breeding population never recovered.

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Despite the huge setback caused by the flies, most pairs forced to abandon their first nesting attempt renested in June. Many such pairs used promising nest locations on islands, protected boggy shorelines, or marshy mounds formed from emergent vegetation; still others placed their eggs of artificial nesting platforms anchored on lakes by lake residents anxious to boost their efforts. And so, in spite of the challenges, many nesting pairs hatched late chicks. These successful pairs included several on lakes that had not produced chicks in many years, such as Hodstradt, Shepard, and Dorothy. They included a few lakes where entirely new breeding pairs had settled, found good nesting places, and hatched young, like South Two, Silver, and Miller. Finally, one breeding pair — on Baker — performed the most impressive feat of all, raising their own loon chick in 2020 after having reared a mallard duckling to fledging in 2019.

Yet all of these heart-warming breakthroughs combined were not enough to lift the breeding rate this year to respectability. As the graph shows very clearly, 2020 continued the steady decline in the reproductive fortunes of northern Wisconsin loons that began over two decades ago. The decline is marked not only by increased black fly harassment but by increased losses of chicks after hatching — both young and old chicks.  Altogether 9 of our pairs patiently sat on their eggs for 4 long weeks only to lose chicks in their first week of life. An additional 8 pairs reared chicks past the “danger period” of the first two weeks but lost one or both chicks later (and a few more, perhaps, will be lost in the coming weeks). In short, we can no longer breathe a sigh of relief after chicks hatch — or even after they reach 2, 3, or 4 weeks. As a matter of fact, I no longer know at what age we should count chicks as having survived. Mortality of chicks of all ages is much higher now than in the 1990s or early 2000s. Statistically, 31% more young loon chicks (<2 weeks) die now than before, and the death rate of old chicks (>5 weeks) has increased by a staggering 81% in the past 28 years.

After having blithely focused my attention on the territorial behavior of loons for a quarter century, I am now compelled to look at what is causing the sharply higher mortality among chicks and young adults. I feel as though I owe it to the folks who live on the lakes of the Northwoods and imagined that they would always hear the sounds of loon calls echo across the water. And I owe it to the loons themselves.

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. 

Raising of a child by one parent alone is common enough in humans that we have words to describe the phenomenon. Since humans are highly social, rearing of a child by a single parent — and a support network of friends and relatives — can be effective. Not so in loons. The loon breeding system could be called “obligate biparental care”, because both male and female are usually required to fledge even a single chick. When one parent is lost during chick-rearing, the typical result is rapid death of the chick or chicks, either because the loon that replaces the dead parent actively attacks them or because they receive much less food and protection from a single parent and perish from other causes. In fact, sustained single-parent loon families only occur when one parent dies or is evicted and the remaining parent somehow manages to sequester the chick from the new adult that fills the breeding vacancy. The occurrence is rare enough that I remember all of the cases in our study area. 

When the Washburn female was injured in 2000, she deserted her family and turned her attention to her own survival. Though it seemed heartless at the time, this decision made sense. Even though helping to rear the chick she left in the male’s care would have increased her reproductive fitness, she was right not to risk her life for the chick. An adult that sacrifices itself for a chick is throwing away many future years of breeding success. After the female left the family, the male spent his time at the northern end of the lake, feeding the chick vigorously when he could. Somehow he managed to fledge it. 

In 2006, the Garth male vanished just after the chick hatched, leaving the female alone to raise it. A single loon mother is in a bind; she lacks the size to intimidate and drive off other loons and ability to give the territorial yodel that could prevent many intruders from landing on her lake in the first place. Instead, single females must tolerate visits by many intruders and hope to keep them away from the chick. A new male soon took over Garth and paired with the female. The female and her new mate seemed to reach some sort of uneasy agreement; she spent time with him, while he neither fed nor attacked his step-chick. The chick, which we banded late in the year and affectionately call “Stripe Hell” because his bands are blue-stripe over taupe-stripe, red-stripe over silver, ultimately survived to adulthood. In fact, as an adult, this male claimed the breeding territory on Lee Lake in 2012 and produced chicks there in 2016 and 2017. Following his eviction from Lee in 2018, this product of a one-parent family settled on South Blue in 2019 and then resettled on Miller Lake this year, where he is now raising a chick with his mate. Apparently having been raised in a single-parent home does not prevent a loon from leading a successful adult life. 

Things do not always go smoothly for step-chicks. When the male succumbed to some unknown ailment on Flannery in 2015, he left his mate alone to fend for their 2-week-old chicks. In this case, the female led the chicks down to Velvet Lake, which attaches to Flannery at its southern end. When a neighboring male took over, he found the chicks and pecked them viciously, killing one and forcing the survivor to hide underneath docks in Velvet to escape his marauding stepfather. This chick never received as much food as a chick normally would; we are not certain if it survived the ordeal.  

Among the several single-parent families we have recorded in 28 years, Squash-Northwest is perhaps the most memorable. The Squash-Northwest male in 2012 hatched a chick with his mate but was injured and died when the chick was two weeks old. Left alone with a small chick, his mate not only protected and raised it to adulthood, she also found a new mate. She was able somehow to balance the demands of her ravenous youngster and the male that she paired with — while keeping them physically separated so that the replacement male did not harm his step-chick. On one visit, we would find her staying close to the chick, feeding it and fending off eagles at the northwestern end; on the next visit, the female would forage and rest with her new mate on southern side of the lake, while the chick hid near shore a kilometer away. While we marveled at the ability of the female to lead this double life and thus to keep the chick alive, we were on pins and needles during the entire chick-rearing period. It seemed inconceivable that the female could sustain her balancing act for the many weeks it would take until the chick was old enough to fend for itself. On each visit to the territory, we expected to find that the chick was dead or severely injured following an attack by its stepfather. Yet the fatherless chick, pictured above and dubbed “Miracle Chick”, not only survived but grew by leaps and bounds.

This year we have a new — and increasingly dark — variation on the single-mother theme playing out on Arrowhead Lake. About a month ago, the right wing of the 12-year-old breeding male became injured. (It is a soft tissue injury, we think, as we did not find a break when we inspected the wing after capture a week ago.) The injured male has engaged less and less with his mate and two chicks over the past month. Instead he spends his time resting and foraging alone on the southern end of the lake. His mate, a seasoned breeder who has produced at least seven sets of chicks with at least three different males on Madeline Lake and Arrowhead, appeared to step up her chick feedings and attendance to compensate for her mate’s absence. Her efforts seemed to pay off; the chick we caught a week ago had achieved a healthy weight, and its sibling (which we did not catch) was of roughly equal size. But the situation has degenerated in the past week. The male, though still alert and feeding himself, shows no signs of recovery from his wing injury and continues to avoid the family. In the past few days, the six-week-old chick that we did not capture was lost (to an eagle, according to lake residents). Today, Lyn reported that intruders landing on the lake roamed about it at will, because neither male nor female showed any semblance of territory defense. It seems only a matter of time before a new breeding pair takes over Arrowhead, and that will likely lead to the demise of the surviving chick. 

Let’s try to be optimistic. If the male recovers and begins to defend the territory again, the chick is in great shape. At six weeks, it has already survived the most difficult early phase of chick-rearing. The veteran female is an attentive mother; perhaps her care can keep the chick healthy in the meantime. And in the sad event that the male does not recover, the female’s efforts might be enough to keep the chick alive and growing even in the presence of a new male. After all, it has been done before. 

In any event, I think I have made my point. Biparental care is almost mandatory in common loons. While a human dad or mom can usually call upon a support network of friends and relatives to help feed and protect their child, a male or female loon that loses its mate during chick-rearing is very much alone. 

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.

As living animals, we often face the task of sorting out meaningful patterns from the vast ocean of natural occurrences we encounter each day. Since we are human and reside in a protective bubble, this task is not as vital for us as for squirrels or deer or loons, of course. If we detect what we think is a natural pattern, act on it, and are wrong, we are unlikely to face lethal consequences. Suppose, for example, that you notice that fewer people do their grocery shopping at 3pm and change your shopping schedule to mid-afternoon so that you can avoid the rush. If you are mistaken, it will cost you time, but probably not your life. In contrast, a squirrel that concludes, based on limited experience, that predators are scarce from 3 to 4pm and decides to begin using that daily period for foraging might pay a dear price if she is wrong.

Despite the low stakes we face, humans have an irresistible and very rational inclination to take note of and try to discern meaning from natural events, especially when those events occur in quick succession. So it was the last few days with loons, bald eagles, a great blue heron, and me. The first incident happened on Squash Lake yesterday. I was watching a loon pair swimming along peacefully with their three-week-old chick. As a great blue heron passed harmlessly over the trio, the chick panicked and dove. Neither parent showed any other behavior in response to either heron or chick; they merely issued reassuring hoots when their youngster surfaced several seconds later, as if to say, “That’s okay; we are all young once!”

The Squash chick’s peculiar response to the heron flying overhead was a beautifully diagnostic act. Since all adult loons know their predators precisely and only flee or give alarm calls to those that are dangerous, I could instantly see from the Squash chick’s behavior that loons must learn their predators. To an animal behaviorist, this is not big news, I am afraid. While some fearfulness towards predators is innate (not learned), many — perhaps most — birds must learn which of the other species of animals they encounter in nature are truly dangerous. Thus, young birds commonly depend upon their parents to teach them.

Though I had witnessed a few other cases of loon chicks responding inappropriately to harmless animals in their vicinity, the striking confirmation yesterday on Squash that loon chicks are clueless when it comes to telling friend from foe was still firmly in my mind when I ventured to Hilts Lake today. There, the loons had to deal with the unpleasant presence of an adult bald eagle and its recent fledgling, which flew incessantly from one side of the lake to the other during my hourlong visit. We try to record every vocalization that the loons make during our routine visits; needless to say, I quickly began to curse the eagles almost as loudly as the loons were for the writer’s cramp they were causing me. I documented about 60 wails by the loon pair during my visit.

Now eagles are dangerous to loons, as I have emphasized recently. It is altogether appropriate that loons should call to eagles as a way of alerting other loons — and the eagles themselves — that their presence has been noted. But 60 wails is a lot of wails — far more than a pair of adult loons would normally produce, even when eagles made themselves so obvious as the parent and fledgling did today on Hilts. Why would a loon pair wail 60 times when 15 or 20 calls would have been ample to alert the eagles that an attack was likely to be fruitless?

Having seen the Squash chick’s response to the heron just a day before the Hilts pair’s overzealous calling to the eagles allowed me to put two and two together into a hypothesis. Part of the reason why loon pairs with chicks are so vocal when dangerous animals are nearby, I now presume, is that they are not merely protecting their chicks from those dangerous animals. They are also pointing out those animals to the chicks so that they will learn what predators are to be feared and respond appropriately once they are on their own.