The Trials and Tribulations of Accomplished Loons



It is hard being successful. I don’t know this from personal experience, of course, but I have studied the topic in some detail. In fact, I spend a disproportionate amount of my time analyzing the behavior and ecology of highly accomplished loons.

You see, the individuals that I talk about in my blog and focus on in my scientific papers are the crème de la crème among loons. These animals have passed myriad biological milestones. They have hatched from eggs, survived the cold and dangerous first few weeks of life, dodged eagles and loon intruders to reach adult size at four months of age, completed energetically-costly molts, and navigated through thousand-mile migrations to and from the ocean. Above all, though, the subjects of my research effort have won battles to claim and defend breeding lakes, found safe nesting locations, and reared healthy chicks. Those chicks — their life’s work — permit my team to capture and mark them for study.

Don’t get me wrong; I did not set out 24 years ago to study this elite class of loons. In fact, I have always been most interested to learn how young adults without territories collect information about potential breeding sites and decide where to settle. But it is difficult to study such “floaters”, because, being floaters, they bounce around. Moreover, floaters cannot be captured easily, because they do not have chicks to protect. Only two years ago did we accumulate enough information to assemble a scientific paper that describes the goals and strategies of this itinerant cohort of individuals.

We are mostly stuck investigating the lives of life’s winners, like “Honey”, the breeding female on Muskellunge Lake whom Linda Grenzer has immortalized in countless photos (see the recent one above). I am not really complaining. We have learned a good deal about the lives of loons in general, despite focusing on the loon elite. Even winners face adversity and evolve interesting strategies to cope with it.

Jeremy Spool, a Ph.D. student at U.W.-Madison who works with Lauren Riters, developed an interesting research question aimed at the coping mechanisms of winners in our study population. Jeremy asked an intuitive, reasonable question about territorial breeders. Territorial pairs, Jeremy thought, should defend their lakes in a way that reflected their recent success. Pairs that had produced chicks in the past few years should be aggressive in territorial defense, because they were defending a resource whose value was clear and which would be costly to lose. Pairs that had not been successful rearing chicks recently might be expected to be a bit more lackadaisical about territory defense. Jeremy tested his hypothesis by exposing some of our territorial pairs to a loon decoy, which simulated a territorial intruder, and measuring their behavioral responses.

Jeremy’s results were unexpected. Pairs with recent breeding success did not behave more aggressively toward the decoy than unsuccessful pairs. In fact, they showed less aggressiveness towards intruders than did failed pairs. But successful pairs were clever about their defense; they became aggressive towards intruders in the few days leading up to egg-laying, a period when territories become vulnerable to intruders owing to incubation. In contrast, pairs without chicks the previous year showed no change in level of aggressiveness during the season. Jeremy concluded that successful pairs save energy by becoming aggressive only when they need to.

What Jeremy’s findings appear to show is that long-term pairs get into a groove with respect to territorial defense, targeting their defense towards times when it is most crucial. As with all good research findings, his raise a number of new questions. One obvious one is “Why should failed pairs be so inefficient about their territorial defense?”.    Another is “Must loons learn to defend their territories efficiently instead of doing so instinctively?”. These are exciting questions for the future that we look forward to tackling. For now, we are celebrating that Jeremy has just had his findings accepted for publication in the Journal of Avian Biology, a flagship scientific journal for avian research.



After a Hooking and a Battle, Loons Look Forward



If you have been following the goings-on at East and West Horsehead lakes, you know that the picture was bleak a few weeks ago. After Iceberg, the female on East Horsehead, was hooked on a fishing line on Memorial Day weekend, she ceased interacting with her mate, YellowBlue, and seemed headed for a rapid, unpleasant demise. Reacting to the loss of a viable mate, YellowBlue searched nearby territories for a new mate, and he gained one after evicting CopperGreen, the male on neighboring West Horsehead Lake. Meanwhile, CopperGreen, after losing his territory, appeared a shadow of his former self, and was reduced to skulking about on the fringe of his former territory to avoid raising the ire of YellowBlue. His mate, WhiteYellow, was left with eggs to incubate and no mate able to help her do so. Thus, the hooking not only threatened the life of an adult loon, it also also compromised the breeding effort of the neighboring pair.

What a difference a few days makes! After a final skirmish with YellowBlue at dusk on the 6th of June, CopperGreen flew off his territory for good to lick his wounds, giving up the fight for ownership of West Horsehead. Fortunately for him, many lakes in the north support no territorial loon pair and yet are full of fish. These lakes are natural soft landing spots for loons displaced from their breeding lakes. One such lake is Birch, where we spotted CopperGreen five days later. But he did not give up his territorial aspirations and settle for a life of ease. In fact, Al Schwoegler reports that CopperGreen has just settled with afflicted female Iceberg on East Horsehead, “across the street” from his former territory. While still bothered by the small jig embedded in her throat (!), Iceberg’s behavior is otherwise normal, and she now interacts extensively with her new mate. So it is possible that CopperGreen has bounced back from his eviction to claim a good territory with a recovering mate.

Meanwhile, back on West Horsehead, things got complicated for WhiteYellow, CopperGreen’s former mate. Having enjoyed an uninterrupted 23-year run as female owner of the West Horsehead territory, during which she produced a whopping 19 fledged chicks, WhiteYellow is a spectacularly productive individual. We cannot impugn her breeding prowess. But in the aftermath of her mate’s eviction, she elected to continue incubating the eggs they had produced. You cannot blame her for trying to hatch these eggs; according to our records, they were within a few days of hatching when her mate met his match. Her decision, however, was fateful. In effect, WhiteYellow was gambling that: 1) she could hatch the chicks as sole incubator and despite spotty incubation owing to black fly infestation, and 2) her new mate would accept and raise the chicks sired by his predecessor.

WhiteYellow has faced such difficult decisions before. Twelve years ago her mate was booted off of the territory late in incubation, yet the evicting male helped her complete incubation of the eggs and rear the chicks. Four years ago, WhiteYellow again completed incubation during a period of male territorial rancor, only to see an evicting male kill the newly-hatched chick. So she knows the ups and downs of continued breeding during territorial instability.

This time, I think, WhiteYellow has erred. Though she continues to incubate sporadically, the eggs are a now a full week overdue for hatching. And WhiteYellow’s hopeful incubation has prevented her from getting on with her life  — bonding reproductively with the evicting male, YellowBlue, so that the two of them might produce a new clutch of eggs and rear some late-hatching chicks.

Apart from the West Horsehead/East Horsehead saga, the news from our study area is mixed. Seventeen of 120 pairs survived the black fly onslaught and have hatched chicks from their first nesting attempt. Another 54 pairs are incubating eggs — nearly all from renesting attempts after abandoned first attempts. A few more pairs will yet try to nest. There is a chance that the newly-formed West and East Horsehead pairs could be among this last group. For the time being, though, they are just hoping for a return to normalcy.

Cool Weather Prolongs Black Fly Outbreaks



I have an almost-annual tradition. Each year at this time, I watch helplessly as black flies harass incubating loons, drive them off of their nests, and force them to dive to gain momentary respite. In years of mild infestation, I breathe a sigh of relief to see that the nest abandonment rate is low. In severe years, I sit down at my computer and try to determine what factors might cause the little demons to hammer loons so hard. Today, I found this. Rate of nest abandonment is strongly correlated with April temperatures. Specifically, cool Aprils seem to cause more nest abandonments. The pattern is strong.

Screen Shot 2017-06-08 at 11.51.27 AM

As usual, I am late to the party. Black flies are of considerable interest because of their negative impacts on humans and domestic animals, so we know a good deal about their biting habits. An hour ago, I excitedly e-mailed one of the world’s experts on black flies to report that cool weather seems to lengthen the period when these pests bother loons. “I am onto something”, I thought. “I must get the word out.” He politely informed me that cool water temperatures slow the emergence of the flies, and cool air temperatures stretch out their lives. He then pointed me to thirteen scientific papers from the past half-century that reached the same conclusion!

The momentary humiliation I experienced was a small price to pay for the knowledge gained. I am now poring over this literature to learn what I can. I have found that most studies of black fly biting patterns are quick-hitters — snapshots from black flies caught in traps over a year or two. Since we possess over two decades-worth of data, our nest abandonment finding expands the information pool considerably. In addition, we have not merely measured how many flies are around or biting, but their apparent impact on the breeding productivity of a well-loved bird. So my excitement about our result is only slightly diminished.

Setting aside the scientific significance of our finding, what does it mean for the Wisconsin loon population? We cannot control outside temperatures, so there seems little hope that the finding will help us mitigate the impact of black flies on loon nests. But if I am correct that cool Aprils are most damaging to loon nesting — and this is a big “if”, as I am still exploring the result — then we might have cause for guarded optimism. A warming climate, while harmful globally in many respects, might provide a slight lift to nesting loons.


Ripples from East Horsehead


, ,

I am still shaken by the recent spate of fishing entanglements. Perhaps my sadness and vexation over these troubling events prevented me from looking clearly ahead. I thought: “Well, the hooked female at East Horsehead will die slowly from the ingested lure, and that will be miserable, but another female will settle on the lake and replace her.” I gained some measure of relief from anticipating the orderly progression of events that would unfold on the lake. As expected, the afflicted female, “Iceberg”, has declined, although she is still not yet weak enough to catch. Her mate, “YellowBlue”, has not stuck to the script, however. Far from waiting passively for another female to settle with him, YellowBlue is proactively seeking a new territory. And that is the problem.

It should have been obvious to me when Nelson reported, last Wednesday, that he saw YellowBlue intrude onto nearby Alva Lake. Females leave their breeding lakes occasionally to intrude onto the neighboring territory; males do so rarely in the height of the breeding season. So YellowBlue’s intrusion was a sign that something was afoot. But I dismissed his visit as an anomaly — the distracted antics of a male whose mate was unwilling to initiate a nest. As it turned out, YellowBlue was probing neighboring lakes for a weak spot, a territory whose owner he could defeat in battle and whose territory he could seize. Based on the aggression and chasing that occurred when YellowBlue visited Alva, the Alva male was not on board with this plan.

But YellowBlue’s search continued. In the next few days, he found a vulnerable male on a different neighboring territory: West Horsehead. We were not present to observe the entire sequence of events, but Al Schwoegler reported yesterday that CopperGreen, the West Horsehead male, was skulking about and hunkering down at the northern end of the lake, far from the nest that he had built with his mate (a 28+ year-old female, “WhiteYellow”, who is among our oldest birds). A quick look at the middle of the lake explained CopperGreen’s diffidence. YellowBlue was foraging and resting there, acting like he owned the place. (Melanie confirmed that this state of affairs continued today.) Now loon behavior in many ways is unsubtle, and territorial behavior is a good example. When a loon is in the middle of a lake, acting like he owns it, he owns it! So YellowBlue had clearly battled CopperGreen, defeated him, and forced him to lay low along the lake’s periphery to escape further attacks. We have seen this sequence of events scores of times. If events proceed normally, WhiteYellow will ultimately cease her efforts to incubate the eggs alone, and the nest will be abandoned. Perhaps WhiteYellow and YellowBlue will renest again this year, but that is doubtful. (CopperGreen, if he is healthy enough, will fly to a nearby undefended lake, like Bearskin, where he can lick his wounds.)

What is troubling about this latest turn of events is the central role played by humans. That is, an angler — a careless or perhaps just an unlucky one — hooked Iceberg on East Horsehead and fled the scene. Iceberg immediately ceased breeding behavior and began a struggle to survive. This turnabout forced her mate, YellowBlue, to go with Plan B, leaving his lake to find another nearby with a healthy female on it. In leaving his own territory and evicting a male on West Horsehead that was sitting on eggs, YellowBlue likely doomed both East and West Horsehead to breeding failure in 2017. So a single fishing casualty affecting a single adult loon has precipitated the loss of breeding opportunities on two of our most productive lakes.

While we are concerned for the impacted loons, this latest eviction has some scientific value. YellowBlue is quite a phenomenon — the youngest male ever observed to evict an established male from his territory. Hatched on Little Bearskin Lake, YellowBlue is only four years old. Perhaps it was his good fortune that CopperGreen was himself only six years old (a product of Oneida Lake). So the YellowBlue-CopperGreen contest featured the youngest combatants ever. I hope that the novelty of this latest encounter takes away a bit of the sting from the event that set it in motion.

All is not lost among loons this year. In fact, one advantage I have, as someone who tracks breeding behavior on 120 lakes, is the capacity to shift my attention away from those where things have gone south to lakes that where all loons are healthy and productive. So let me end with a beautiful photo of Linda’s from Muskellunge Lake that will remind us that there are lakes where loons are free of hooks, where they defend their territories successfully, and where the next generation thrives.

LMG5508 Clune Yodeling Tight with Family2-2


Memorial Day’s Painful Toll



To most people, Memorial Day weekend is both a sacred and joyous occasion. It is a time to remember those who have given their lives for our country. And it is a holiday that lets us gather around the barbecue with friends or enjoy an extra day of rest followed by a short work week. In the northwoods of Wisconsin, Memorial Day often brings a hint of summer’s warmth at a time when we are not quite free of the clutches of winter. Memorial Day convinces us that summer will return to the north.

Since 1993, when I first starting studying loons in northern Wisconsin, I have dreaded Memorial Day. On this holiday weekend, throngs of anglers bolt from their southerly homes for the northwoods to throw a hook in the water. Meanwhile, loon pairs that have managed to fight off black flies, eagles, and raccoons are well into the four-week incubation period. Memorial Day is the time when hopeful loon parents and hopeful human anglers collide.

I used to gird myself for the disturbance to nesting loons that humans caused each Memorial Day weekend. Fishermen and boaters commonly disregard or do not see loon nests and venture close to them, driving loons off of nests for a time. But such incursions now seem innocuous. They seldom cause great problems for loons, who sometimes complain but dutifully jump back on their nests after boats have moved off.

Now that we have better connections to the local community, I see that the substantial danger posed by humans to loons on big fishing weekends is not from flushing off of nests but from fishhooks and monofilament line. On Memorial Day weekend, the loon pictured in Linda’s photo, a female that reared a chick on Nokomis Lake in 2010, was hooked in or near its throat while it foraged on Nokomis. As ugly as it is to look at the silver hook buried in its throat and the local swelling that resulted, the Nokomis female might recover. She appears to be hooked externally, and Linda reports that she dives strongly.

A second female fell prey to an angler’s lure this Memorial Day. This bird, the mother of many recent chicks on East Horsehead Lake, apparently swallowed a lure or bait used by a fisherman. Initially Linda found that this female was severely impacted, often trying to jump onto the shoreline, as loons do when seriously injured. Nelson and I raced up to East Horsehead to help Linda and her husband, Kevin, try and capture this bird and transport her to a wildlife rehabber for treatment. But our efforts were in vain. The bird had bounced back and begun to dive normally, despite the fishing line protruding from its bill. Having ingested a lure, this bird’s long-term prospects are rather dim. She will certainly die if she swallowed a lead sinker.

These two cases illustrate a vexing paradox often faced by those of us trying to protect wildlife: animals commonly become injured in a way likely to kill them eventually but not so catastrophically that immediate capture is possible. So we must wait and monitor them until creeping hunger or infection reduces their mobility sufficiently for us to grab them and see to their injuries. These are most unpleasant and heart-wrenching vigils. Moreover, these occasions often end badly, if the animal becomes compromised beyond the point of recovery before it can be captured and treated. Still, knowing that a grave injury of this kind has occurred gives us a chance.

An encounter with fishing tackle ended quite badly for the East Horsehead male last year. Although it was not reported to us until a few days ago, last year’s East Horsehead male — the long-time mate of the female who swallowed a lure a week ago — became hopelessly ensnarled in monofilament line last August. Based on our records, we surmise that he succumbed to this entanglement sometime after August 10th, as we observed the female alone caring for the chicks on our two visits after that date. (Since the chicks were 11 weeks old by late August, they likely survived to migrate south. That, at least, is a relief!)

We were disappointed to hear only now about the unpleasant entanglement and death of the East Horsehead male. Unlike the two females, this male was probably immediately compromised enough by the fishing line that we could have captured him and cut him loose in good condition and with no harm to his survival prospects. Indeed, we were able to save a female on Perch Lake from a similar predicament in 2010. Since the East Horsehead male’s plight was never communicated to us, he had no chance.

So, now, a plea. Please let folks know that angling casualties happen. We are anglers ourselves and understand this. But anglers who cut the line and flee the scene after accidentally hooking a loon — or observe a loon in distress and fail to report it — are turning a dangerous situation into a catastrophic one. As so often occurs, it is the cover-up, not the crime, that causes real damage. (I am happy to take reports of loons in distress at Let’s try and have summer holidays in the northwoods bring to mind the events they were meant to commemorate, not the toll they exact on loons.



Jersey City Flowage Leads the Way



My world gets turned topsy-turvy each year when the first chick hatches. Each year at this time most pairs are struggling just to hold their territories, find safe nesting sites, lay eggs, and fight off the black flies that chew on them. Today, for example, I visited four established pairs that had built nests and laid eggs, but only one — I am proud to say it is the pair on our home lake, Currie — is still incubating the eggs. The others had abandoned their nests owing to black fly infestation. Four lakes is too few to draw conclusions, but my findings today illustrate the debacle produced by black flies again this year. I am just not quite sure how to reconcile the carnage I saw today on my circuit of lakes with the engaging photo that Linda Grenzer took of the Jersey City male alertly guarding his chick.

I suppose the clearest message sent by the news of a successful hatch is that the world is varied and bright spots remain. Indeed, many loon pairs are beating the black flies and thriving. In fact, a few dozen pairs will follow JCF’s lead and hatch young in the next week or two. Moreover, most pairs that have fallen victim to black flies will lay a second clutch of eggs shortly; there is still ample time to hatch and rear young that can migrate south in November. So do not worry if the loons on your lake are swimming distractedly about right now instead of sitting on eggs. They will likely get back to it soon. In the meantime, take heart — as I am trying to — in the photo above.



One Egg Too Many on Wind Pudding


What I witnessed on Wind Puddling lake yesterday is an occurrence we have seen many times now. Instead of the usual two-egg or one-egg clutch, a pair has three or even four eggs. Why the supernumerary egg(s)? There are two likely explanations. First, the female’s cycle of egg production might have been thrown off, causing her to add a third egg, when she would normally have shut down after two. Second, the female laid two eggs, then the pair abandoned them, but they have reused the first nest site and simply added two fresh eggs to the two, old, addled ones from their first nesting attempt.


We know that both 3-egg clutches and reuse of a nest containing abandoned eggs can explain extra eggs in loon nests. In 1997, the Washburn Lake female laid three viable eggs within a single nesting attempt. All three eggs hatched, in this case, producing three small chicks. But the task proved too much for the pair. They lost two of the chicks quickly and settled for raising of a single chick that year. That is the only case we know of where a female deposited three eggs in quick succession into a nest and had them all hatch. All other cases of three or four eggs in a nest have resulted from adding of two new eggs to a nest already containing two old, dead eggs from a first abandoned clutch. This is quite common.

Why would loons behave this way? First, let me point out that safe nest sites are sacred to loons. That is, they search — sometimes for years — to locate a site safe enough that the eggs hatch. Once a male has found a successful nesting site, he is loathe to leave it. So we can understand why a pair might wish to reuse a good site. The question is: why do loons not remove spoiled eggs from a nest before laying fresh eggs there? While it would seem highly inefficient to sit on four large eggs, when you are used to sitting on only two, loons have many times hatched chicks from four-egg nests. Thus, loons are capable of keeping four eggs warm. It may even be that the extra eggs provide a bit of extra warmth buffer, since having warm neighboring eggs helps each egg remain warm itself. So perhaps the answer to why loons do not discard the dead eggs is that leaving them in the nest has no cost and might even bring a slight benefit.

Nevertheless, I do not enjoy seeing a sight such as I saw at Wind Pudding. Supernumerary eggs almost always mean that black flies have been savaging the loons again. While not as severe as 2014, 2017 has been another year of black fly abundance. Many pairs have stuck doggedly to their nests, enduring the hateful pests. But about an equal number have already given up on their first nesting attempt or appear on the brink of it. If that attempt occurred at a favored nest location that produced hatched eggs in the past, we can expect to see more sights like this in the coming weeks.

A Chick Returns Home….But Why?

As the intruder flew in and began to descend onto Townline Lake, I barked at my assistants,”Make sure you have your binoculars trained on the bird when it dips below the trees. That is when you can see the bands.” They hastily complied. “It’s banded!”, Melanie gasped, as the bird wheeled and landed about 150 yards from us and near the non-incubating pair member. We paddled our overloaded canoe as quickly as we could to join them and were tickled to see that the other pair member had decamped from the nest and was also racing alongside us to confront the intruder. Fortunately, the three loons engaged in stereotyped social behavior (circling and diving and bowing heads) and permitted us to approach them closely during this period. So we easily read all four colored leg bands on all three birds. This meant that we had the data we needed to later identify the intruder from our records.

Intrusions are relatively scarce during incubation, so Melanie and Tammy had seen few encounters between territory owners and intruders. Tammy remarked afterwards that the three birds had seemed to interact in a friendly manner. That is, they had exhibited social behavior and excited diving, but no aggression. Indeed the encounter had remained amicable for a full hour, at which point the intruder had finally separated itself from the pair and departed from the lake. “They acted as if they knew each other”, remarked Tammy. While seeking to purge all condescension from my tone, I explained to her that this was unlikely to be the case. “Intruders”, I explained, “are acting selfishly: they visit pairs in order to size them up as potential opponents in battle, often making repeated visits. At a certain point, an intruder learns that the owner of its sex might be vulnerable and then attempts to evict the owner in battle.” Since we had many years of data to support this interpretation of intrusions, I was quite confident in my explanation.

But I was wrong. At least, I was wrong in this case. Since we nailed the band combinations perfectly, it was a simple matter to look up the intruder in the banding database afterwards on my phone to find out that “Wb/Wb, S/Ar” was banded as a chick on – wait for it – Townline Lake in 2013. Since the Townline pair have both been on the territory for 15 years or more, this male intruder was the 4-year-old son of both pair members. In other words, we had just witnessed a family reunion.

Naturally, I was befuddled. My fluent, engaging discourse on the selfish and violent aims of intruders, which had seemed like gospel moments before (at least to me), was dashed upon the rocks. In a desperate attempt to wipe the egg off my face, I offered a Rube Goldberg of a hypothesis. Perhaps, I suggested, young intruders pass through a period during which they do not intrude to take over a territory, but instead seek only to sharpen their social skills. If young adults do need to develop social skills as a means to lay the groundwork for full-blown attempts at territorial eviction, then it might be the case that youngsters are less picky about where they intrude than older intruders. Such age-dependence in territory targeting by intruders might explain why they would even intrude into their own natal lake and interact with their parents, as this 4-year-old male had done.

While rather complex, my thrown-together “social learning” hypothesis is plausible. Equally important, it generates precise predictions. First, young nonbreeders (3-5 years old) should intrude into more different lakes than older nonbreeders (6-9 years). Second, for reasons of incest avoidance, older intruders should never visit their natal lake, which is likely to be owned by their parents still. In other words, loons looking to evict the owner of an established territory should not intrude into their natal lake, while young loons aiming only to learn how to behave socially might be expected to intrude in their natal lake — and everywhere else. I have not yet looked at intrusions systematically to look for this age-based pattern, but I was curious enough, after our recent observations on Townline Lake, to do a quick check. Two other cases of young nonbreeders intruding into their natal lake fit the expected pattern. One of these birds, in fact, was a mere two-year-old when it visited its parents on Bolger Lake.

We must analyze more data to see if we have a statistically significant pattern showing that young nonbreeders are those that tend to visit their natal lakes. But so far, the pattern is holding up. Who knew? In many cases, we scientists blunder upon a finding – as happened here – when we make an observation that does not fit the view of nature that we had constructed. Indeed, this is one of the rewards of our discipline.

Nerds and Nuance


A few years ago, my daughter and I were talking about her high school homework. I cannot recall precisely what class we were discussing, but a moment occurred when I became concerned that she was unprepared for an upcoming test. Anxiety hung in the air for a second before she reassured me. “Dad”, she said with a twinge of impatience, “I am a nerd”. It was her way of telling me that she was studious, exacting, and did not need to be told to get her work done.

As you all know by now, I too am a nerd. I wear that label — like my daughter does — as a badge of honor. The nerds I know are thoughtful, bookish folks who enjoy making fine distinctions and extracting subtle patterns from scientific data. Nerdiness of this kind is essential to a scientist, of course. Publishing our work and being taken seriously by our colleagues requires that we navigate a mine field of biased samples, uncontrolled variables, and specious correlations to arrive at valid conclusions to our questions.

Nerds are different. Most people, while chatting with a stranger in a supermarket line, can get away with saying, “Aaron Rodgers killed the Packers last year with his erratic passing in big games”. A nerd, however, would want to look at the data. S/he would examine Rodger’s passing statistics against teams with winning records and division rivals to see if, truly, he played worse in those games than in less important contests. While nerds can be annoying nit-pickers in society — the kind of people you want to avoid sitting next to at a party — we are quite valuable as scientists. We have the patience and passion to discover true causes of patterns in nature.

I was able to bring this patience to bear on a recent question about loon behavior. In my ongoing investigation of senescence in male loons, I faced a puzzle. The territorial yodel of males serves two purposes. It is, most obviously, a territorial call that males emit when a competitor is flying overhead or sitting nearby in the water. At such times, the yodel announces the willingness of a male to fight for territory ownership. But the yodel also serves to protect the young (see Linda’s photo, above); that is, male parents often yodel to prevent landings of flying intruders, which sometimes attack and kill chicks. Why does it matter that the yodel serves two purposes? Because I am trying to make a nerdy distinction: Do old male loons yodel more than young males because they are defending their territories, or do old-timers yodel more simply to defend their chicks?

This distinction is important. If you have been following this blog, you know that old male loons make a terminal investment in reproduction. The most obvious evidence of terminal investment by old males is their tendency to yodel more often than young males. But since yodels occur both in territory defense and in chick defense, it was not immediately obvious whether old males were yodeling their heads off at intruders simply to protect their chicks or to maintain ownership of their territories. Fortunately, we have enough yodel data from periods with and without chicks to see if the increased yodeling of old males occurs at both times. It does! Hence it seems that old males are employing the yodel call to defend their territories as well as to defend their offspring.

To a nerd, the ramifications of this finding are profound. An old male who yodels simply to protect his chicks is investing extra energy to rear his offspring to adulthood at the possible expense of his own survival. This is rather a short-term strategy, as it is aimed at rearing young to 11 weeks of age, after which young are out of the woods, and the investment has been successful. An old male without chicks that yodels, however, is taking a long-term view. Chickless males are months away from producing young. Their yodeling is aimed at guaranteeing territory ownership for many future months, even years. Although terminal investment in offspring is rare in animals, terminal investment in territory ownership is virtually unknown. So the stepped-up yodeling by old, chickless male loons is an exciting finding. As you might imagine, this result has set off quite a nerd celebration!

Nesting Is Underway


As we expected from the early ice-out, nesting has begun a bit ahead of schedule. Linda’s photo shows “Clune”, a male hatched on Manson Lake in 1998, on a substantial nest mound in a marshy part of Muskellunge Lake. If all goes well for them, Clune and his mate (“Honey”) will alternate incubation duties for four weeks. Their reward will be 1 or 2 needy hatchlings that they will have to shield from the elements, protect from eagles and other loons, and feed tirelessly for three months. With luck, their efforts will yield two big, fat, sassy chicks, like those pictured here.

But they have a long way to go. May is the month when black flies emerge, bite loons mercilessly on the nest, and generally make them wish they had hands instead of wings. Al from West Horsehead reported today that the flies have driven the pair off of their egg for the time being. Since we know from experience that loons are loathe to abandon a nesting attempt, we hope that they will resume incubation shortly. (Surprisingly, eggs can hatch despite loons spending considerable time off the nest.)

I will return to Wisconsin in a few days myself to race around the study area and find what nests I can. I hope to find those nests by observing loons sitting peacefully on them, rather than thrashing about in the water nearby in a vain effort to rid themselves of their winged tormentors.