The two-year olds have done it again. At an age when most loons are loafing, feeding, staying out of trouble, and just trying to survive, a second two-year-old has shown territorial pretensions. This time, the loon is a female. This time, the territory is in our Minnesota Study Area.
The discovery occurred three days ago on Pig Lake. Although I always smile at its undignified name, I was a bit sad to visit Pig, because neither pair member from 2022 had returned this spring. This fact reminded me of the generally poor return rate in Crow Wing County and my growing concern for loons in Minnesota. So as I gazed through binoculars at the whitecaps on Pig, I braced myself for what more bad news the lake might have to offer.
But among the four loon heads bobbing about in the surf, I was thrilled to spot a banded loon. This bird was one of a pair that dived in close synchrony off of Black Pine Resort. “One of the missing pair members is back!”, I whispered to myself, hopefully. Further observation dispelled that notion. The loon’s right leg showed two colored leg bands. Since all loons banded as adults get a metal band on the right leg, two plastic bands on the right leg meant that I was not watching one of the missing pair members, but instead observing an “ABJ” (adult banded as juvenile). That is, we had banded this loon as a chick.
Two possibilities leapt to mind. This bird might have been a one-in-a-million, 200-mile disperser of undetermined age from the Wisconsin Study Area, where we have been banding adult loons and chicks since time immemorial. Almost equally unlikely, the ABJ might have been one of our first crop of Minnesota chicks banded in 2021. The plot thickened as I compared the size of the ABJ and its mate. The banded bird was clearly smaller. I was looking at a rare female ABJ!*
My efforts to nail the ABJ’s color bands from my solo canoe were not immediately rewarded. I loosely followed the foraging pair, bobbing and spinning about comically amidst the churning waves and boat wakes. Eventually a moment came — forty minutes into my chaotic paddle — when the ABJ and I were carried to the crests of adjacent waves and the bird raised its legs clear of the water. I confirmed that the bird was blue over auric red on the right and red over silver on the left. “B/Ar,R/S”, my notes revealed, was marked as a chick on Ossawinnamakee – Muskie Bay territory on 18 July 2021. So this was indeed a two-year-old female hatched a short distance from Pig.
What are we to make of this astonishingly early territorial behavior by separate individuals in Wisconsin and Minnesota this year? Nothing at the moment, I think. Two rare events do not constitute a pattern. But those who follow the blog closely might recall that a decline in the population of floaters — mostly young adults not yet settled on territories — is one of the hallmarks of the current downward turn in the Wisconsin population. If we continue to see two- and three-year olds compete for territories in ways they did not 15 years ago, we will have to regard it as another indication of a limited pool of nonbreeders in Minnesota and Wisconsin** — and, hence, further evidence of a broad decline in the Upper Midwest loon population.
**The logic is simple here. If there are few young adult floaters (usually 4-, 5- and 6-year olds) in a population competing for territories, then even very young floaters (2- and 3-year olds) might be able to acquire one, despite their generally lower competitive ability and aggressiveness.
We have never observed a two-year-old adult male or female settle on a territory. Indeed, we have only once observed a loon as young as three claim a territory — and that was very late in the season and in a vacant space without competitors. (His mate, sad to say, was his mother.)
But “Junior”– as Linda calls the two-year-old that has settled on Muskellunge — threw out the book on reproductive maturation. When the 12-year-old male that took over on Muskellunge this year became injured in early June after a failed nesting attempt, Junior took possession of the lake and began defending it vociferously with territorial yodels (as you can see in Linda’s photo, above).
For a time, it seemed that Junior would ease into lake ownership without a battle. Yet news that Muskellunge Lake was up for grabs spread fast in the neighborhood, and the last two weeks have seen multiple local males vie for control. One of these males, from nearby Deer Lake, has tried to claim Muskellunge before and is renewing his bid. A second male, this a ten-year-old reared on neighboring Clear Lake, seemed settled on Harrison Flowage last year but is apparently looking to upgrade.
Junior’s age is not all that makes his story unusual. He is also the only young adult (out of 211 observed so far) that we have ever observed to compete for ownership of his own natal territory. In this he is fortunate; the current breeding female on the lake, who will probably pair with the victorious male, is not Junior’s mother, but instead a female that took possession of Muskellunge last year.
According to Linda’s reports, Muskellunge remains in an uproar. One day Junior is in control and paired with the resident female (or the Bridge Lake female, whose mate did not return this spring). The next day the Deer male has taken ownership and patrols the lake, searching for Junior, who evades him.
Linda and I are trying to celebrate the oddity of a two-year-old territory owner and not overthink it. But it is difficult to sit back and pretend to be neutral. After all, Junior got his name because he is the son of Clune, the beloved male who settled on Muskellunge in 2009, cranked out 14 chicks during 14 years of territory ownership, and never uttered a discouraging word for canoe nor kayak.
And it is hard not to wonder how a loon as young as Junior even got a shot at such a good territory. Is his territorial gambit an anomaly — a one-time peculiarity that you are bound to observe once if you study a loon population for 31 years? Or must we interpret his premature, longshot bid for territory ownership as yet another indication of the depleted ranks of young nonterritorial loons that epitomize population decline in the region?
Loons in the Upper Midwest have just survived a worse-than-average year for black flies. “Worse-than-average” might not be the way to put it. In a reverse Lake Wobegon scenario, worse-than-average black fly years are the new normal in Wisconsin and Minnesota. Nowadays, we know black flies will be awful; we only wonder how awful.
Researchers who venture close to a loon nest abandoned to flies get a small taste of the agony these insects inflict. As if moved by a sweeping dipteran consensus, a cloud of flies buzzing about a nest — drawn by warmth, movement, and carbon dioxide— suddenly shifts its attention to approaching humans. The flies alight on your head and neck, crawl underneath your jacket, and fly errantly into your nose, ears, and mouth. The experience is unpleasant and alarming. It is difficult not to scream.
Yet the tactile and chemical cues humans produce are not satisfying to black flies. They crawl and buzz and annoy. But they do not bite us. So we cannot say that we truly know how loons feel when they are besieged by black flies — when the mouthparts of hundreds of females are inserted into their head and neck at once and departing flies are quickly replaced by new ones that have been waiting their turn to feed. And when it lasts for hours. That helpless miserable sensation is one that humans can only imagine.
Black flies swarm about the nesting platform and Ethan McKone on Blue Lake-West in the Wisconsin Study Area. May 22, 2023.
Despite the misery they cause, black flies have one great virtue. They plague incubating loons for only a few short weeks.
In the past seven to ten days, black fly numbers at loon nests have dropped substantially. You do not need me to tell you this; the loons have weighed in. Two weeks ago our marked loons in Minnesota and Wisconsin rested and foraged near their nests, gazed longingly at their nests, circled around their nests, and — on a few occasions when we ventured too close — defended their nests from us. This past week has been different; loons are ON their nests. Thus, after a stuttering start, the breeding season has begun.
It is easy to forget that research on the loons of Crow Wing County, Minnesota has been underway for over a decade. To be sure, this work has been spotty. From 2011 to 2014, Kevin Kenow and his USGS team placed geotags on a few dozen adults on four medium-sized lakes in the county. From 2015 through 2017, he shifted his efforts to the Whitefish Chain, where he captured 68 individuals, including 36 territorial adults.
Kevin’s goal was to determine migration and wintering routes of Minnesota loons, which he did after recovering many of the geotags placed on loons’ legs. Although his study was short-term, Kevin’s loons lived on. Each summer and fall they nested and reared young, foraged to build up their reserves for migration, staged on the Great Lakes, and made long overland flights to the Gulf of Mexico. Each spring they molted their feathers and made return trips back to the Whitefish Chain to restart the cycle.
When our Minnesota Loon Project began in 2021, we relocated many of the loons Kevin had banded 4 to 6 years before. We were quite thorough — obsessive, even — in our efforts to do so. At the time I regarded the USGS banding effort as fortunate for us, since it gave us a head start in our efforts to mark all territorial pairs on the Chain.
But Kevin’s marked loons have not merely reduced our loon marking workload. Kevin’s birds are charter members of the Minnesota Loon Project. The survival of these inaugural adults since the years Kevin’s team marked them provides our first multi-year snapshot of adult loon survival in Crow Wing County.
The data provide an unconventional snapshot. When one conducts a mark-recapture study, one normally searches diligently for all marked individuals during the years immediately after marking. This strategy produces data on annual return rate, which provides an estimate of annual survival. But we lack data on return rates from 2018, 2019, and 2020. So we must do the best we can to extract information from Kevin’s birds despite multiple years with missing data.
Fortunately, this is not rocket science. If “r” is the annual rate of return, then r2 is the probability of being on territory two years after banding, r3 is the probability of still being present three years later, and so on. Recognizing this, we can easily project how many of the 36 territorial adults that Kevin banded in 2015, 2016, and 2017 should have still been on territory in 2021. If annual rate of return were 90%, we would have expected to see 20.5 of Kevin’s loons in 2021. At 85%, the expectation is 15.1. If the annual rate of return were 80%, then we should have seen 11.0 loons. In fact, our exhaustive search turned up 13 of Kevin’s loons. So this places our rough estimate of annual loon survival for the Whitefish Chain at 82.5%.
To my knowledge, ours is is the first long-term estimate of adult loon survival from Minnesota based on a marked population. This is rather shocking; loons are well studied in the U.S., have been marked in at least ten states….and are the state bird, for goodness sake! In any event, this preliminary estimate gives us a ballpark figure for adult survival that we can compare with more robust estimates from other states.
The data from Minnesota so far only provide a glimmer about the loon population in Crow Wing County. However, these low survival estimates do bring to mind a worrisome downward trend in loon numbers for the region that can be seen in the 2021 Minnesota Loon Monitoring Report. But, really, it is early days. We need more data. Furthermore, the status of a loon population is not dependent upon adult survival alone. Low adult survival can be offset by a high reproductive rate. So we will have to spend at least two more years tracking return rates of marked loons and measuring breeding success before we can pull them together into a model that will tell us (preliminarily) how Crow Wing loons are doing. Still, if I am being honest, I wish the survival numbers were a bit higher.
Thanks to Katy Dahl, who photographed the Cross Lake-Arrowhead Point loon pair after we banded them in 2021. The male in the foreground with his bands out of water was spotted a few days ago just north of Minneapolis.
If, like us, you are concerned about the persistence of loons in Minnesota, consider a donation to support our field efforts. We run a lean program. Funds donated to the Loon Project do not pay overhead, administrative costs, or salaries for staff or senior personnel. They pay only field costs like: 1) stipends to keep student field workers alive, 2) travel costs to, from, and within our study areas, and 3) supply costs such as for colored leg bands and canoe paddles. Thanks!
I should have known all along. I should have known last May, when the ancient outboard motor we had just bought to cover the Whitefish Chain spewed a foul rainbow sheen onto the water’s surface and belched a caustic purple cloud that momentarily blinded us. I should have known as I filled huge tanks of gasoline at the Holiday convenience store in Crosslake, hefted them down to the dock, and hooked them up to the belching motor. I should have balked at the absurdity of using a filthy, fossil-fuel-guzzling outboard to study an animal that requires clean air and water.
Instead, I shrugged. “This is how people get around in the Northwoods”, I thought. “This is inevitable. This is the environmental cost of studying loons on big lakes.”
In my own defense, my understanding of proper boating practices became ingrained during my childhood. Back then, when we needed to provision our cottage on an island on 40-mile-long Lake Temagami in central Ontario, we took our little 2-stroke outboard over to the Ojibway Store on Devil’s Island. I still recall taking in the pleasing aroma of balsam fir mingled with mixed gasoline as we listened to the soft lapping of waves against the store’s dock. At the time, my major concern was whether Mom would treat us to Burnt Almond bars when she had finished ordering our groceries. Gasoline was just an innocuous part of the landscape we inhabited.
Indeed, to folks of my generation and generations adjacent, the angry whine of an outboard motor, the slap of a stiff wind in our faces, and the sight of parting, churning waters behind us seem inextricably linked to the pungent smell of gasoline.
But it need not be so. There is a growing market for electric outboards (and inboards) that can replace gasoline motors smoothly and are far cleaner (of course), quieter, and — according to what experts say — very reliable and low-maintenance. I have been researching this.
Why have I experienced this sudden desire to go electric on the water? Two reasons. First, the last two Wisconsin field teams and I faced an absolute nightmare every time we tried to start up our vintage 9-horsepower Evinrude. I did not collect data on our efforts, but I believe we averaged 43 almost-shoulder-dislocating tugs of the starter cord per lake to get that dirty old 2-stroke started. I have had it! (I believe Sarah ’22, Molly, Claudia, Chris, Tia, Bailee, and Sarah ’21 will applaud this move.)
Second, I can no longer deny the obvious. The relentless march of climate change has begun to hurt loons in the Upper Midwest. We can see it in the increase in the May black fly population, which forces loon pairs to suffer horribly as they to incubate their eggs, often to the point of abandonment. And it is even more evident in the sharp decline in July water clarity during the past quarter century (see below) — a decline that impairs loon parents’ ability to find food to feed their chicks. Both increased black flies and decreased water clarity, we now know, come about in large part because today’s warmer, rainier summers produce more flowing water that: 1) supports increased black fly reproduction and 2) washes more matter into lakes that reduces clarity.
So I have finally figured something out that I should have guessed before. Climate change is hurting loon populations in the Upper Midwest in multiple, measurable ways. Cutting back on fossil fuel usage where I can will help slow this damaging pattern. And that is a step in the right direction.
After losing our primary source of funding for Minnesota, we are facing a money crunch. The news came rather suddenly. It has left me pondering this sea change in our circumstances and wondering where it leaves us.
It is ironic to lose our funding at this particular moment. After intensive field efforts in 2021 and 2022, the Chapman/Loon Project database now contains two full years of field data from Minnesota. We have made scores of friends and lake contacts — mostly through the tireless efforts of students on the LP field team in Minnesota. Having marked one or both adults on 57 of 105 territories we cover in and around Crosslake, we are more than halfway to our goal of building out the Minnesota Study Area. Completion of our marking efforts in 2023 and 2024 would bring Minnesota up to par with our long-term study population in Wisconsin. Most important, we have roughly half of the necessary data to construct the first-ever true population model in the state using marked loons. So it is only a slight exaggeration to say that we have accomplished in two years in Minnesota what it took us 10 to 15 years to achieve in Wisconsin.
In short, our 2021 and 2022 field teams in Minnesota have built a great LP database that has all of the promise we thought it would. I would be remiss if I did not thank Kevin and the USGS loon capture team that contributed mightily to our banding efforts in 2022. A bunch of other folks helped out with capture and tracking of the Minnesota population in 2021 and 2022, including Mike and Natasha of the NLC, Richard and Terri, Dawn and Keith, Mary, and Kris. Jon, Melanie, and Mike from Boyd Lodge housed the field team during our work. Mike and John loaned us their boats. (Apologies if I have forgotten someone.)
Naturally, now that we have established a robust study population from which we will soon be able to extract reliable population data, I am acutely concerned about the sudden funding shortfall. But should you share my concern? If you live in Wisconsin or Maine or Ontario, why should you care about Minnesota loons? After all, we have excellent long-term data on the northern Wisconsin loon population that provides a sensitive gauge of the population trend in one part of the Upper Midwest. Why can’t we generalize the results from Wisconsin to Minnesota? In other words, if the Wisconsin loon population is thriving or tanking, isn’t it safe to presume that the Minnesota population is doing the same?
Minnesota and Wisconsin loon populations certainly seem similar. The states share a lengthy border across which loons fly freely. We have learned from recoveries of our banded birds in other seasons that the migration and wintering grounds of Wisconsin and Minnesota loons overlap almost completely. Adult loons in Wisconsin and Minnesota are of very similar size — and both populations contain adults much smaller than the loons of New England. Loons consume the same species of fish, are plagued by the same species of black fly, and must dive, duck, and dodge boats and fishing lures in both states. Importantly, lead fishing tackle — banned in New England — kills many adults and chicks in Wisconsin and Minnesota both. And, of course, loons are also loved and fiercely protected by most lake residents and visitors in Minnesota and Wisconsin. Doesn’t all of this mean that the population trend we detect in Wisconsin loons is likely to hold also in Minnesota?
Perhaps. But there are also differences. In general, loons appear to be packed more densely in Minnesota than in Wisconsin. Weather patterns, while broadly overlapping, differ between the states. Minnesota loons are more northerly, on average, than loons in Wisconsin. To presume that the two states’ loon populations fluctuate in harmony is risky. And, of course, if the Minnesota loon population echoes the Wisconsin loon population, our Minnesota measurements are even more important to make. Remember, the northern Wisconsin loon population is in serious decline. Minnesota loons could be declining in concert with Wisconsin loons, could be stable, or could be declining more rapidly than Wisconsin’s loons. Without running the numbers, we just don’t know.
The condition of Minnesota loons matters for another reason. Since loons in the Upper Midwest experience many of the same hazards as loons across the breeding range (e.g. water clarity, black flies, human angling, lead toxicity, and recreational pressure), our detailed and rigorous observations in Wisconsin and Minnesota have implications far beyond the Upper Midwest. By studying two populations 200 miles apart, we can compare factors that impinge on loons across populations. Any common patterns that we see across the two study populations are likely to indicate factors of broad impact — factors probably important in New Hampshire, Quebec, and Montana.
My discussion of the Minnesota loon population exposes a second irony. Minnesota provides a summer home for more loons — by a 3 to 1 margin — than any state in the lower 48, and Minnesotans love their state bird. Yet Minnesota arguably knows less about its loons than any other state in the contiguous U.S. (As I pointed out some months ago, what data we do have on Minnesota loons create cause for concern.) The LP database in Minnesota — once we finish building it and can build a model to learn about population dynamics — would permit us to remedy this unfortunate irony regarding Minnesota’s loons. Our work would alert us to any decline in the state, and our accompanying study of causes of reproductive failure could help us design and put in place a conservation plan that (with luck) could reverse any decline. Yet with this crucial milestone in sight, we suddenly lack the funding we need to reach it.
In truth, we have always faced challenges in Minnesota. Our most important lake there is Whitefish, which contains about a third of our territories, and where we are sometimes driven off of the lake by brutal winds and whitecaps. Even our “small lakes” in Minnesota are, on average, 50% larger than those in Wisconsin, which forces us to spend longer periods finding study animals by canoe. When compared with Wisconsin, everything is expensive around Crosslake and often in short supply — that goes for lodging, storage space, equipment, and most everything else. And tacking a Minnesota Study Area onto the Wisconsin Study Area has doubled my annual workload. Despite my determined efforts, I have not spent enough time in Minnesota nor have I been able to adequately support the field team there. Considering the 1,329 obstacles we confront in Minnesota — to which we can now add lack of funding — maybe we should throw up our hands and throw in the towel.
But then, loons could say the same. Territorial pairs face enormous obstacles each summer in trying to raise chicks. They must find safe nesting sites, defend them from predators, and incubate their eggs for four long weeks regardless of weather conditions. Hatching, which would appear worthy of a celebration, is, in reality, not even a halfway point for the pair. Instead, hatching merely introduces a new suite of hazards for parents, including new predators, the threat of infanticide by intruding loons, and the difficulty of finding enough food for their chicks — especially if they are on a small lake and it has been a rainy summer. And, of course, both parents are in constant danger of being evicted from their territory by young upstart loons that are always on the prowl for breeding territories. In short, the task of raising two healthy chicks, or even one, is incredibly daunting. If loons had the ability to ponder the vast array of obstacles to successful reproduction, they might never attempt it.
The desperate struggle of loons to raise young despite a host of challenges was illustrated vividly by the loon pair on the Little Pine-Dream Island territory this year. Little Pine is a pleasant, rather quiet lake on the Whitefish Chain. We marked the Dream Island pair in 2021, during which they raised a chick. Both pair members returned this year, so we knew they were veterans with a track record of chick production. But their experience in earlier years did not prepare them for the buzzsaw they encountered this past summer. When we found the Dream Island pair on May 27th, they were off the nest and spending a great deal of time under water. We quickly learned why. Black flies were tormenting them mercilessly. The relentless flies were present in huge numbers on the nest and on vegetation near the nest. They frolicked in great clouds in the air above the nest. And the pair members’ heads were blanketed by flies, each probing the skin for a spot to make an incision. Even constant diving by both male and female failed to dislodge these blood-sucking pests. During our visit, the male (pictured below in the water near the nest) made a pitiful attempt to mount the nest and resume incubation, but he could not bear to do so.
After surveying the nightmare scenario at Dream Island, I gave them a low probability of resuming their incubation duties in time to rescue the eggs and hatch their chicks. It did not seem possible that a male and female whose heads and necks were thickly encrusted with welts from hundreds upon hundreds of fly bites would see this nesting attempt through to hatching. But by some miracle, the pair hatched both eggs successfully three weeks later. I was flabbergasted. Despite 30 years spent watching nesting behavior of loons, this one successful attempt against all odds remains seared into my brain. It is impossible to know how many female black flies participated in the blood-letting of the Dream Island pair. But I suspect, like us, they had at least 1,329 reasons to quit.
I find myself drawing inspiration from the Dream Island pair. No one could have anticipated that they would hatch their eggs after facing such an unexpected and disheartening challenge. Yet offered the temptation of bowing to adversity, they stuck it out and triumphed.
Field ecologists are often told that they come to resemble their study animal. I am not dismayed by this comparison. In fact, if I can bring half as much determination and stick-to-it-iveness to my research program as the Dream Island pair bring to their nesting efforts, I will consider myself an unalloyed success.
This seems a good time for me to emulate the Dream Island loons and resist the temptation to give up the Minnesota work. The stakes are enormous. Minnesotans would be devastated to lose loons from the state or even from part of the state. And based on my work in neighboring Wisconsin, Minnesota loons are likely in trouble. Do I turn away from these good people — and a new set of loons with which I have begun to bond — when I meet some adversity?
So I am asking for your help. If we are able to raise $3,500, that will permit us to go to Crosslake and complete the late May census of the 105 or so loon territories that comprise our study area there. The census is a vital part of the year’s field effort, because sightings (or non-sightings) of adults we marked in 2021 and 2022 permit us to calculate the rate of return to the territory from the previous year, an indication of adult survival. If we are even more fortunate and receive $7,000 in donations for the 2023 Minnesota field effort, that will allow us to complete the all-important May census and also visit the territories again once or twice in July to determine rate of reproductive success. Reproductive success is a second important piece of demographic data that will help us refine the population model we build in two years. Finally, if by some miracle we are able to pull together $17,000 for Minnesota, that will permit us to do the census, measure reproductive success late in the year, and band enough new loons to bring our Minnesota Study Area up from two-thirds finished to fully marked. The 2023 banding effort would increase our sample of banded birds and strengthen the population assessment we will carry out in the near future.
If you have already donated to our study, thank you so much! If you have not yet contributed financially to our work and are now able to assist with our Minnesota field effort, we would appreciate it! As I have explained, your donation will be spent in an effort to learn about and conserve Minnesota loons. (If you wish to donate funds, but would like your donation to go to helping loons in our traditional Wisconsin population instead of the new Minnesota population, please specify that when you donate, and we will honor your request.)
Feel free to e-mail me at wpiper@chapman.edu if you have questions about our fundraising effort and how you can help. For example, if you can offer us housing in the Crosslake area for a week in May and/or for ten days to two weeks in late July, that would reduce our funding needs greatly and bring us closer to our goals.
Thanks for any help you can give us. I am anxious to complete the promising work that we began two years ago and will move heaven and earth to keep the Minnesota Study Area afloat. Things look grim at the moment, but I am hopeful that, like the Dream Island pair, I can weather adversity and emerge stronger on the far side of it.
We all love loons. So naturally we should take any step we can to help them. Right? In that light, artificial nesting platforms (ANPs), or loon rafts, would seem to be a no-brainer. Platforms make it easier for loon pairs to produce chicks.
ANPs fit neatly within the framework of loon conservation. Accepted enthusiastically by most loon pairs, they would seem to provide a perfect, low-cost solution to increase loon populations. They are easy to construct; a person with a modicum of carpentry experience can find plans online and build a platform in a day or less. So platforms provide a simple method by which a single loon enthusiast can improve the breeding success of a pair of loons for many years. Across the loon breeding range, platforms have become a panacea for bolstering reproductive success.
But are nesting platforms all that we need them to be? Now that loon populations appear to be in trouble in Wisconsin and perhaps even in Ontario — and now that some of the causes of declines are beginning to come into focus — maybe it is time for us to step back for a moment. Maybe we should ask whether platforms address the actual problems that loon populations face. To state it technically, can platforms mitigate the specific negative factors hurting loon populations and make populations viable in the long term?
We first need to recognize that platforms address a single, very narrow problem faced by loons. Loon pairs must sit on their eggs — in an exposed location — for 28 days. If a mammalian predator wanders by during that month, the nest is lost. Platforms solve this problem beautifully. They increase the rate of hatching by about 70%. But putting chicks in the water is all platforms do. Platforms do nothing to help chicks reach fledging age. They do not feed chicks; they do not protect chicks from predators. They do not boost adult loon survival. They have no effect on the rate of boat strikes or angling casualties or lead poisonings of adults and chicks. In short, if loon populations suffer declines owing to reduced hatching success, then nesting platforms are just what the doctor ordered. If declines are caused by anything else, then platforms would appear ill-suited to the task.
What do we know at this point about the status of loon breeding populations and factors that might threaten them? Precious little, if we are talking about the entire species range. But we have begun to narrow down the list of population threats in the Upper Midwest.
How well does the use of nesting platforms to boost hatching success of loons map onto the quadruple threat of increased black flies, decreased water clarity, lead poisoning, and spiking mortality of young adults? With respect to black flies, platforms might mitigate the problem somewhat. Platform-nesting loons suffer abandonments just as severely as do loons nesting at natural sites, but the increased hatching success of second nests on platforms offsets the hit to hatching success caused by black fly-induced abandonments of first nests. Platforms, of course, have no impact on the decreased growth rate and increased mortality of loon chicks owing to declining water clarity and the resultant difficulty of feeding chicks. Likewise, platforms do not affect the incidence of lead poisoning. And platforms provide no relief to loons from the silver spoon effect, whereby individuals reared with limited food survive poorly as young adults.
On the whole, then, floating nest platforms do not appear to address effectively the major threats faced by loon breeding populations (to the extent that Wisconsin represents loon populations generally).
While that quick analysis might seem reasonable, I have ignored one crucial fact about loon nesting habitat and platforms. Platforms often provide loons with an opportunity to breed in lakes or parts of lakes where they otherwise could not because of the absence or poor quality of nesting habitat. In other words, platforms actually create new nesting habitat. If the new nesting habitat that platforms make available contains enough food that parents can fledge the chicks they hatch there, platforms might provide “bonus chicks” that give the loon population a boost. *
Of course, platforms are so enticing to loons that they must be deployed thoughtfully. A platform placed on a very small lake might lure a pair of loons to use it but result in starvation of the chick(s) because of food limitation. Since a pair lured into such a tragic situation might otherwise have nested and reared chicks successfully elsewhere, such misuse of nesting platforms exacts a cost on the breeding success of the population. (Loon conservationists recognize the pitfalls of using nesting platforms thoughtlessly and only deploy them where they are likely to do more good than harm.)
While loon platforms seem effective at boosting loon populations in some respects but ineffective or even harmful in other respects, what conclusion can we reach? We cannot be too confident of any conclusion at this point. But since it is becoming clear that poor foraging conditions during the chick phase is the greatest problem for loons and that limited food during the chick phase can doom a loon to a short adult life, we would do well not to pat ourselves on the back too hard for adding a platform that puts a few extra chicks in the water.
* Population ecologists will recognize a potential flaw in my reasoning. Even if platforms result in a huge increase in fledged chicks in a population, density-dependent mortality during winter or migration (e.g. owing to food shortage) might wipe out all of these extra individuals. In that case, platforms would not be an effective conservation tool. In fact, increased adult mortality from a variety of causes could produce population decline even in the event of huge “bonus” chick production via platforms.
I am never prepared for chick loss. As a scientist, I know that the first several weeks of life are fraught with danger for loon chicks. Have they developed normally? Can they thermoregulate properly? Are they able to dodge eagles, muskies, and snapping turtles that can devour them when small? Are their parents aggressive and vigilant enough to keep intruders at bay, which might otherwise kill them with a few well-placed jabs? Is there sufficient food in their natal lake to sustain them and support their rapid growth? And these are merely the natural threats to chick survival.
As hazardous to chicks as natural dangers, or perhaps more so, are threats that humans pose. Sometimes these are direct impacts; humans drive their boats rapidly and often strike chicks, which cannot elude them as deftly as adults. Anglers’ lures and baits, recognized as unnatural and avoided by most adult loons, are sometimes gobbled up uncritically by chicks, which are just learning what they can and cannot eat and must gorge themselves in order to grow. The hooks — and especially lead jigs and sinkers that they ingest at such times — pose a grave risk to the youngsters. A more insidious and dire threat that we have seen recently is the decline in water clarity in northern Wisconsin in the past decade, which makes it difficult for chicks and parents to find food and likely explains much of the reproductive decline we have seen there. (We will soon determine whether water clarity is declining in loon lakes in Minnesota as well.)
Although I am acutely aware of the increasing dangers that loon chicks face, I struggle to adjust to the steady drip drip of chick mortality in Wisconsin and Minnesota. When the Rush-USA Point pair lost their chick, I reasoned, “Well, that territory gets high boat traffic; it is hard to keep a chick alive there.” I justified the loss of the Cross-National Loon Center chick and the two chicks hatched by the Rush-Hen pair in the same way. I was a bit numbed by the time I considered the loss of the two young chicks of the Eagle-East pair.
I find it easier to stomach brood reduction. When broods decrease from two chicks to one, I take solace in the survival of the remaining chick. So it went at Upper Whitefish-Steamboat, Ossie-Island, and Sand this year. Very often brood reduction of this kind comes about because food is limiting; the death of the smaller chick actually gives the larger chick a fighting chance to make it.
What stings the most is loss of chicks that have reached four weeks of age. In the past few days, two chicks that had attained this milestone perished in the Minnesota Study Area. (The NLC is awaiting necropsies on both individuals.) Quick inspection of the Lower Hay-Southeast chick that lost its life and washed ashore earlier this week showed what appeared to be traumatic injury on the back, suggestive of a propeller strike. When you consider that the Lower Hay-SE territory is right next to a major public boat landing, this likely cause makes sense. The second deceased chick, from Clear Lake, was 32% lower in mass than its sibling; thus it was falling far behind in acquiring food from its parents. So this looks like classic brood reduction. Indeed, Kate Marthens, one of our Minnesota field team, reported that this chick was not keeping up with its family on the day that it was found dead, an indication that brood reduction was imminent.
The significant increase in mortality of loon chicks of all ages (i.e. both younger and older than five weeks of age) is a hallmark of the current population decline in Wisconsin. I should be learning to cope with it — preparing myself to face it in Minnesota too, if our growing sample there reveals the same trend. But that is more easily said than done. It still hurts like the devil to lose a chick.
Featured photo — One of our largest chicks in Wisconsin is that on Little Bearskin Lake. It was alive and kicking as of this writing! (Molly Bustos, a Wisconsin intern, holds the bird.)
Yesterday, I heard the cheerful, buzzy calls of Japanese White-eyes* flitting about in the trees in my backyard. They are handsome and engaging little birds, but they don’t belong in southern California. They never lived here before humans did. As recently as ten years ago, white-eyes were quite difficult to find in the area.
A few weeks ago my wife, son, daughter, and I visited my ailing mother in Houston. On our first morning there, we were awakened by the incessant cooing of White-winged Doves*. They too are a striking species. The flashy white stripes on their wings and tails set them apart from the more familiar and homely Mourning Doves. Even the ceaseless calling of White-wings is rather pleasant. Don’t trust me on this; the abundant murmurings of this species inspired Stevie Nicks to write an entire song about them. But White-winged Doves have not always lived in the Houston area. I remember scouring trees around the Galveston County Courthouse in vain for this species with my mentor, Fred Collins, on a Christmas bird count a half century ago.**
Of course, while new species colonize new regions; well-established residents also vanish. In the Upper Midwest, the Piping Plover, a cute little shorebird, has recently become severely threatened. Though I have never seen a Piping Plover in all my years in Wisconsin and Minnesota, I do have experience with a second threatened species, the Black Tern. These agile fliers flit about marshy areas, plucking insect larvae and small vertebrates from the water and vegetation. They are appealing birds — with jet-black bodies that contrast tastefully with greyish wings and tail. But it is a longshot to find them in the Upper Midwest nowadays. What seemed a healthy breeding colony fifteen years ago on Wind Pudding Lake in northern Wisconsin — where we have always had a breeding loon pair — has disappeared altogether. It has been so many years since I last saw Black Terns on Wind Pudding that I have stopped looking for them there.
In short, my years as a bird-watcher have taught me that populations of birds change dramatically over time. Some species magically appear in new places, and other species disappear. I suppose it is my first-hand experience with the dynamics of avian populations that infuses my current research on loon populations in Wisconsin and Minnesota with such urgency. This is why I sweat the black fly season in May and June, worry about boat strikes and lead poisoning, and am in a bit of a panic over the recent loss of water clarity in the region. I have now seen — as I had not in 1993 when my loon work began — that birds can disappear.
* Photos by Natthaphat Chotjuckdikul and Ted Bradford from eBird.
** In fact, the picture is a bit complicated in the case of this species. White-winged doves occurred commonly in the southwestern U.S. 100 years ago, but the population was devastated by the expansion of the citrus industry. However, in the past three decades, the species has begun to nest in citrus trees and has come roaring back.
